Re: [time-nuts] eLoran is up and operating. Looking good

[Bob Camp]

Hi

A very practical contribution one *could* make would be to enhance the drivers 
for the radio based systems. Propagation is a big deal with any of the radio 
setups. Loran is no exception to that. Teaching the NTP drivers when not to
use the data and how to compare data is a do-able thing. It’s just that nobody
has ever bothered to do it. Coming up with some simple to use tools to estimate
the errors and config them in is likely the only practical way to do it.

Bob


> On Feb 7, 2017, at 12:10 AM, Ruslan Nabioullin  wrote:
> 
> On 02/06/2017 09:06 PM, Bob Camp wrote:
>>> On Feb 6, 2017, at 7:38 PM, Ruslan Nabioullin

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Re: [time-nuts] eLoran is up and operating. Looking good

[Bob Camp]

Hi


> On Feb 6, 2017, at 7:38 PM, Ruslan Nabioullin  wrote:
> 
> So any ideas on how likely it will be that eLORAN becomes deployed with at 
> least partial US coverage within the next 5--10 years?

No, this is not the world as I would like it to be. It is the world we live in 
now and are likely to live in for the foreseeable future. 

If we are looking at it purely as a timing reference the outlook is not real 
good. Best guess about 1 in 1,000. I’m probably estimating 
that on the generous side. If there is some other magic use for the thing (or a 
couple dozen other uses) that might change the 
equation. Right now those other uses are not very obvious. 

Why the lousy outlook:

1) The way a system like this gets funded is for it to have  a lot of users. It 
might also get 
funded if some crazy black project needs it. That’s not happening with Loran. 
Loran died in
the first place due to a lack of users. 
2) For a system like this to have a lot of users, you need to pass regulations 
requiring it’s use. 
That may seem odd, but that’s the way it works. Loran co-existed with GPS for a 
long time.
GPS was *less* reliable back then than it is today.  Using Loran for timing was 
a very rare thing
outside a handful of labs. 
3) To regulate it into major systems, it needs to have at least a country wide 
coverage and 
more likely a bit more than that. Without that there isn’t enough of a timing 
market to address. 
You need to retrofit it into every cell tower in the country (for instance). 
4) Loran getting into buildings from a single site (even fairly close) … not so 
much if they are 
full of switching power supplies, you have a problem. You need to have *many* 
Loran transmitters. Cell timing 
is moving out of the “edge” and into the central hubs. That means buildings 
full of switchers. 
5) Tying multiple time sources into a system costs big money. If you only have 
two clocks, how
do you decide which one is wrong? Not an easy question to answer. That money 
has to come
from somebody. Nobody wants to pay. The cell carriers have never been excited 
about 
investment that does not immediately result in more customers. 
6) There are multiple competing “for pay” backup timing systems. Adding another 
one to
the mix is pretty hard to justify. Even more so if you can “steal” timing off 
of one and 
not pay for it. That would be the case with an eLoran that works with all our 
old gear. 
7) Like it or not, justified or not, cost effective (not), the world is hung up 
on space based
systems. There is no excitement in 1950’s technology. 
8) Loran for exact timing has some major issues with propagation delay. If your 
goal 
is the same as the system specs ( < 100 ns) that’s going to be a really tough 
nut to
crack. Do they *need* < 100 ns? It’s in the spec … 


Will they keep studying it as long as they can get funding for the study? Of 
course they will. 
How long will people keep pitching in for that funding … could be years. Five 
to ten year
studies that go nowhere are not at all uncommon. 

Right now we have multiple broadcast time sources running 24/7 at various 
frequencies 
with various coverage zones. As far as I know *none* of them are tied into 
major systems. 
That’s just the way it is, and it’s nothing new. Even in military systems, 
multiple time sources
into a system is a very rare thing. In commercial systems … 

Again, I’m not arguing that this is an ideal world. 

Bob


>  There exists a solid company working on its R&D (UrsaNav), apparently 
> increased awareness in government, and UrsaNav entered into a partnership 
> with Spectracom for integrating its UN-152B (modern SDR-based eLORAN, 
> Loran-C, and Chayka frequency and time transfer receiver) for GNSS fallback, 
> which has been tested for commercial applications (e.g., NYSE), so apparently 
> there is some commercial demand (I have been told by an engineer at Google 
> that they are aware of this for Spanner and their other R&D projects 
> requiring time metrology, but have not decided yet).
> 
> -Ruslan
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Re: [time-nuts] low power, but quiet, oscillators

[Bob Camp]

Hi

> On Feb 6, 2017, at 7:35 PM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> On 02/07/2017 12:36 AM, jimlux wrote:
>> On 2/6/17 2:37 PM, Bob Camp wrote:
>>> Hi
>>> 
>>> One of the most basic reasons for putting out > +20 dbm is that you
>>> had a spec of -195 dbc / Hz for the noise floor :)
>>> 
>>> Some of these specs *are* a bit mutually exclusive.
>> 
>> Sure.. And to be honest, I'm not sure that some of the folks coming up
>> with paper requirements for these speculative low power transmitters are
>> aware of that.  They take dBc values from 1 Watt transmitters and assume
>> you can meet that with your 1 mW transmitter.
>> 
>> 
>> 
>> Then again couldn't you cool your oscillator.. that gets the T part of
>> the kT down lower 
>> 
>> Cool that puppy down to <1K and get 25dB noise improvement, eh?
> 
> Your 50 ohm termination resistor will be a great source of that noise.
> For a narrow-band fixed signal you can terminate with whatever reactive 
> network you feel confident with instead. If you match impedance well enough 
> it will work fairly well. Some oscillators have far-out impedances far from 
> 50 Ohm anyway so impedance matching is so-so and most of the noise comes from 
> the termination resistor.
> 
> Besides, for the deep space stuff you have cheap access to 2.7 K or so 
> anyway, right? :)

Ok so, I have a device that puts out 1 mw (0 dbm) of power. I want the phase 
noise to be -195 dbc. What 
source and load resistance do I use?  :)

I *can* use an infinite load, that will get me a whopping 3 db of noise 
improvement. That only 
leaves another 17 or so db still to be found. Of course I’m not going to 
deliver 1mw into
an infinite load so we now loop back through what does putting out 1 mw really 
mean? 

If my source is purely reactive I have a phase angle between voltage and 
current. I now have energy
coming out and not power. Back to the same question about 1 mw. 

Yes you can run in and out of rabbit holes for weeks on this one :)

Bob

> 
> Cheers,
> Magnus
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Re: [time-nuts] low power, but quiet, oscillators

[Bob Camp]

HI

> On Feb 6, 2017, at 6:36 PM, jimlux  wrote:
> 
> On 2/6/17 2:37 PM, Bob Camp wrote:
>> Hi
>> 
>> One of the most basic reasons for putting out > +20 dbm is that you
>> had a spec of -195 dbc / Hz for the noise floor :)
>> 
>> Some of these specs *are* a bit mutually exclusive.
> 
> Sure.. And to be honest, I'm not sure that some of the folks coming up with 
> paper requirements for these speculative low power transmitters are aware of 
> that.  They take dBc values from 1 Watt transmitters and assume you can meet 
> that with your 1 mW transmitter.
> 
> 
> 
> Then again couldn't you cool your oscillator.. that gets the T part of the kT 
> down lower 
> 
> Cool that puppy down to <1K and get 25dB noise improvement, eh?

Sounds like a low cost solution :)

The other proposed solution is to source the signal out of a zero ohm source. 
It’s not clear
which one actually costs less.

Bob

> 
> 
> 
>> 
>> Bob
>> 
>>> On Feb 6, 2017, at 3:19 PM, jimlux  wrote:
>>> 
>>> We're always looking for low DC power, but quiet (close in), oscillators 
>>> for spaceflight applications, particularly as the spacecraft get smaller.
>>> 
>>> I was intrigued by the paper Ulrich posted which actually called out a "mW 
>>> RF out for mW DC in" as part of their FoM.
>>> 
>>> Is there a list somewhere of what sort of DC/RF efficiencies are 
>>> possible/typical.  In particular, I'm interested in topologies/designs that 
>>> put out low powers.. (1 mW or less).  There's lots of designs that put out 
>>> a convenient +10dBm or +13dBm or 3.3V CMOS square wave or whatever.. but 
>>> sometimes, you only need to radiate a few mW  (I would think the low power 
>>> Bluetooth/Zigbee/802.15 folks have been thinking about this)
>>> 
>>> Jim
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Re: [time-nuts] low power, but quiet, oscillators

[Bob Camp]

Hi

One of the most basic reasons for putting out > +20 dbm is that you 
had a spec of -195 dbc / Hz for the noise floor :) 

Some of these specs *are* a bit mutually exclusive. 

Bob

> On Feb 6, 2017, at 3:19 PM, jimlux  wrote:
> 
> We're always looking for low DC power, but quiet (close in), oscillators for 
> spaceflight applications, particularly as the spacecraft get smaller.
> 
> I was intrigued by the paper Ulrich posted which actually called out a "mW RF 
> out for mW DC in" as part of their FoM.
> 
> Is there a list somewhere of what sort of DC/RF efficiencies are 
> possible/typical.  In particular, I'm interested in topologies/designs that 
> put out low powers.. (1 mW or less).  There's lots of designs that put out a 
> convenient +10dBm or +13dBm or 3.3V CMOS square wave or whatever.. but 
> sometimes, you only need to radiate a few mW  (I would think the low power 
> Bluetooth/Zigbee/802.15 folks have been thinking about this)
> 
> Jim
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Re: [time-nuts] Lucent KS-24361 REF 0 standalone

[Bob Camp]

Hi

The only serial dialog between the two units is a repeat of the output of the
GPS module. My guess is that there is some subtle difference between
the Oncore data and they skytraq….

Bob

> On Feb 6, 2017, at 1:23 PM, Thomas Petig  wrote:
> 
> Hi everyone,
> I am currently trying to repeat previous work of members of this list in
> convincing the REF 0, to run standalone with a given 1PPS signal from a
> gps. Similar to:
> https://syncchannel.blogspot.se/2015/08/standalone-operation-of-lucent-ks-24361.html
> 
> I am using a skytraq gps with 100ms, 74AC04 for inverting and level
> shifting and I added the jumper wires on J5. I simulate the Oncore
> messages with a python script using a usb->uart cable and triggering on
> the 1PPS pulse on the CTS line. I am sending @@Ea, @@En, @@Bb, @@Ap,
> @@Aw, @@Ag, @@At, @@Az, @@Bj, @@Bo with a delay of 75 ms, as suggested
> in the blog above:
> https://github.com/thpe/oncore/blob/master/oncore_emu.py
> 
> Surprisingly, I have a constant delay of 0.8 ms, and only a jitter of
> +/-0.1 ms for the oncore messages compared to the pulse on the CTS line.
> 
> Short everything is working and if I force external 1PPS usage it locks
> to it (NO GPS light goes off). Using pForth:
> 1 force_ext_1pps
> 1 force_gps_1pps
> 
> But, it does not do it on its own, since it ignores the tracking mode
> for the satellites and, I guess after reading the Z3801A manual,
> therefore it claims the GPS 1PPS signal as invalid. E.g., for the entry
> with @@Ea:
> 0x02, 0x08, 0xFF, 0x82
> meaning satellite 2 in mode 8 (used for positioning) it assumes mode 0.
> The other values, like signal strength 0xFF and channel status 0x82 are
> taken, even if I change them to something else. The mode value is
> ignored no matter what it says.
> 
> In the attached files on sees that "GPS 1PPS Invalid: not tracking", and
> the mode of the is 0. I forced it to use the external 1PPS signal.
> 
> So, the question what tiny detail did I miss while reading the mailing
> list archive and those blogs on how to set the REF 0 up for standalone
> operation just using the Oncore messages?
> 
> Does someone has dump of the communication between REF 1 and
> REF 0, until the REF 0 is happy (I don't have a REF 1)?
> 
> Regards,
>   Thomas
>   DK6KD
>   SA6CID
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Re: [time-nuts] Optimal oscillator topology for diffrent frequency range

[Bob Camp]

Hi

One could easily spend years answering this sort of question. Several people on 
the 
list *have* done so. Two of them have already tossed up answers. 

What are you trying to do?

What is your definition of “low”? 

How well equipped are you to test this sort of thing? 

How much tweaking are you willing to do?

Do you have a source of (custom) low noise crystals?

Lots of questions and lots of twists and turns in the answers as a result. 

Bob

> On Feb 6, 2017, at 4:06 AM, Yeti Yetos  wrote:
> 
> Good morning,
> What's the optimal  oscillator topology for low phase noise (low frequency
> noise and phase noise floor) for  25Mhz/50Mhz/100Mhz frequency  range.?
> 
> Best regards, Rafal
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Re: [time-nuts] What interrupts aging?

[Bob Camp]

Hi

Nothing in life is perfect :)

Diffusion of ions in the lattice is one of the more obscure sources of aging. 
It is maybe 
number 10 or 15 on the list. The exception to that would be high radiation 
environments 
where you have energetic particles trying to knock things around. A similar 
(but different)
effect is the diffusion of the electrode material into the blank. For normal 
electrodes, that is 
well past number 20 or so….(and no I don’t have an exact list …)

Bob

> On Feb 5, 2017, at 7:19 PM, Peter Reilley  wrote:
> 
> I am curious: is the quartz in a high quality quartz crystal perfect?That 
> is; is the
> 
> crystalline lattice perfect, without flaws or impurities?   I assume that the 
> quartz is
> 
> grown in a furnace, can we grow perfect quartz crystals?
> 
> Pete.
> 
> 
> On 2/5/2017 6:31 PM, Bob Camp wrote:
>> Hi
>> 
>> Aging can be caused by many things. Stress on the blank (and can and leads 
>> and plating and …) is one
>> source. There are good reasons to believe that quartz vs metal stress can 
>> take > 1 month to settle out
>> to the 90% level. Particle (think borders down to atoms) equilibrium inside 
>> the can is another source.
>> Adsorption / desorption rates on many of the likely candidates also run out 
>> into the > 1 month range.
>> More or less — you can adsorb stuff in a few seconds that takes many weeks 
>> to desorb. Yes this is
>> only the start of a very long list ….
>> 
>> How long an interruption to stir things up? Does the oven go to full power 
>> after your interruption? If it
>> does, things are likely to get tossed around and aging (or retrace or warmup 
>> or whatever you want to
>> call it) is going to get going.
>> 
>> Pile on top of this the fact that crystals are not the only thing that does 
>> aging like things. Capacitors
>> have a fun characteristic known as dielectric absorption. Some (tantalums) 
>> have leakage that drops
>> a LOT with time spent at temperature and voltage. Either way,  bump the 
>> voltage and things move around
>> for a while. Use the wrong caps and it can be quite a while.
>> 
>> Next layer is keeping the OCXO at the same temperature. When a “normal” OCXO 
>> is sitting there on
>> the bench, it’s in it’s own very specific temperate zone. Convection (and 
>> maybe other things) have acted
>> over quite a while to set up that zone. Touch it / bump it / move it / blow 
>> on it …. you will change the
>> temperature. Most likely you will change the gradient across the package. 
>> Rick wrote some papers
>> back in the 90’s about why this really messes things up…. ( Again this is 
>> the start of a very long list …).
>> It’s even longer if you have DAC’s and voltage references external to the 
>> OCXO.
>> 
>> So yes, you can get aging a lot of ways. Knowing what is and what is not 
>> aging can get a bit complicated.
>> 
>> Bob
>> 
>> 
>>> On Feb 5, 2017, at 3:11 PM, John Ackermann N8UR  wrote:
>>> 
>>> We know of OCXO that have been continuously running for years and have 
>>> exceptional aging, supposedly as a result.
>>> 
>>> What does it take to interrupt that? A momentary loss of power?  The oven 
>>> cooling down?  Some long period of off-time?  Or, once the oscillator has 
>>> baked in will it return to that low aging once it has been powered up and 
>>> thermally stabilized?
>>> 
>>> John
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Re: [time-nuts] What to do with a 5061A/5061B with dead NiCds

[Bob Camp]

HI

Unless you are in a *very* unusual location, put it on a UPS. 

Bob

> On Feb 5, 2017, at 6:27 PM, Skip Withrow  wrote:
> 
> Hello time-nuts,
> 
> I have 5061A and 5061B units with the battery option and dead battery
> packs.  My question is what makes the most sense when refurbing these units?
> 
> 1.  Yank the old battery out and just leave it that way.  Running the unit
> on a UPS would preserve the functionality.
> 
> 2. Replace the pack with a rebuilt NiCd pack.  I'm sure Batteries Plus
> would be happy to do it, but sounds expensive.
> 
> 3. Replace the pack with a NiMH pack, and really crank down the float
> current of the 5061.
> 
> 4. Replace the pack with Li-ion battery.  Would be a much smaller battery,
> but the charging circuit would have to be pitched.  Building in a Li-ion
> charge controller sounds like it could be a project (which I don't
> necessarily want).
> 
> 5. Yank the old battery pack and run the 5061 on two 12V batteries with an
> appropriate power supply/charger (basically a version of #1).
> 
> Any thoughts on these or other options would be appreciated.  Thanks in
> advance.
> 
> Regards,
> Skip Withrow
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Re: [time-nuts] What interrupts aging?

[Bob Camp]

Hi

Aging can be caused by many things. Stress on the blank (and can and leads and 
plating and …) is one
source. There are good reasons to believe that quartz vs metal stress can take 
> 1 month to settle out 
to the 90% level. Particle (think borders down to atoms) equilibrium inside the 
can is another source. 
Adsorption / desorption rates on many of the likely candidates also run out 
into the > 1 month range. 
More or less — you can adsorb stuff in a few seconds that takes many weeks to 
desorb. Yes this is 
only the start of a very long list ….

How long an interruption to stir things up? Does the oven go to full power 
after your interruption? If it
does, things are likely to get tossed around and aging (or retrace or warmup or 
whatever you want to 
call it) is going to get going. 

Pile on top of this the fact that crystals are not the only thing that does 
aging like things. Capacitors 
have a fun characteristic known as dielectric absorption. Some (tantalums) have 
leakage that drops
a LOT with time spent at temperature and voltage. Either way,  bump the voltage 
and things move around
for a while. Use the wrong caps and it can be quite a while. 

Next layer is keeping the OCXO at the same temperature. When a “normal” OCXO is 
sitting there on 
the bench, it’s in it’s own very specific temperate zone. Convection (and maybe 
other things) have acted 
over quite a while to set up that zone. Touch it / bump it / move it / blow on 
it …. you will change the 
temperature. Most likely you will change the gradient across the package. Rick 
wrote some papers 
back in the 90’s about why this really messes things up…. ( Again this is the 
start of a very long list …). 
It’s even longer if you have DAC’s and voltage references external to the OCXO. 

So yes, you can get aging a lot of ways. Knowing what is and what is not aging 
can get a bit complicated. 

Bob


> On Feb 5, 2017, at 3:11 PM, John Ackermann N8UR  wrote:
> 
> We know of OCXO that have been continuously running for years and have 
> exceptional aging, supposedly as a result.
> 
> What does it take to interrupt that? A momentary loss of power?  The oven 
> cooling down?  Some long period of off-time?  Or, once the oscillator has 
> baked in will it return to that low aging once it has been powered up and 
> thermally stabilized?
> 
> John
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Re: [time-nuts] information about the Austron Synchronous Filter 2090A

[Bob Camp]

Hi

Best guess - it was intended for use in close proximity to a Loran chain 
transmit 
site.  The Austron Loran receivers only had about a 100 db dynamic range. If you
needed to operate close to a transmitter … that’s not enough.

Bob

> On Feb 5, 2017, at 3:20 AM, Ruslan Nabioullin  wrote:
> 
> On 02/05/2017 02:58 AM, Poul-Henning Kamp wrote:
>> I belive [sic] the idea is that if you have two Loran-C receivers
>> tracking two different GRIs, the 2090A can blank out the strongest
>> stations [sic] pulses for the weaker chains [sic] receiver.
> 
> So it functions sort of as a preselector, one whose universe of
> discourse is LORAN-C, for improved reception performance of the receiver
> tracking the weaker GRI?
> 
> -Ruslan
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Re: [time-nuts] Power Problems Lucent KS-24361, L101 & L102

[Bob Camp]

Hi

The power “brick” is a pretty standard Lucent part. The show up from time to 
time
on the surplus market. The gotcha is that you may be able to buy a KS box for 
less
than the asking price for the power brick. 

There are no schematics on these devices other than what some people have traced
out here and there. The input to the power brick is simple enough that it’s 
probably 
worth simply tracing out on the board. That will involve pulling the board 
completely 
out of the chassis (which is a pain). Once it’s out, some quick ohm meter 
checks between
the power inputs and the labeled pins on the power converter will give you a 
pretty 
good idea of what goes where. There *might* be a pc board mounted fuse on there
somewhere ….

Bob

> On Feb 4, 2017, at 8:54 PM, Roland Wm Buzz Ude  wrote:
> 
> I,m brand new to this forum. I need your help. While powering up a KS-24361 
> set of units for the first time, my power plug for P1 was wired incorrectly!. 
> Pin one (P1) was plus 24 VDC; Pin three (P1) minus 24 VDC--this
> should have been pin two Tried same connection on both L101 and L102, no 
> activity of any kind. Where does pin three (P1) connect. I may have trashed 
> both units. Are schematics available. Thanks W8BUZ
> 
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> https://www.avast.com/antivirus
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Bob Camp]

Hi

For NTP grade timing, there are still a lot of broadcast sources out there. 
You *do* need to be careful about propagation and when to (not) use 
them during the day. Focusing effort on that part of it is probably more
useful than waiting for funding to appear for eLoran….

Bob


> On Feb 4, 2017, at 11:51 PM, Ruslan Nabioullin  wrote:
> 
> On 02/03/2017 10:02 AM, paul swed wrote:
>> Ruslan
>> NH will be easy to pick it up. The core frequency is 3 Cesiums in a
>> cluster. As for time transfer it can but its really a pain in the
>> backend and that information is indeed in the data channel. So make
>> us jealous with your CS and RBs. :-) I am down in Franklin Ma so we
>> are actually close compared to others.
> 
> I'm actually jealous of your LORAN time/frequency metrology capability :).  
> Apparently UrsaNav (headquartered locally in North Billerica, MA!) are the 
> ones performing these particular aforementioned R&D efforts; I have visited 
> their corporate website and have read about their projects and product 
> portfolio, and have developed a liking for this company (despite being 
> anarchosocialist).  The reason is that philosophically I'm a strong advocate 
> of resilient technology and social policies, and consequently that is the 
> entire purpose of my nonprofit time/frequency metrology and transfer project. 
>  As an example, the redundant timekeeping and NTP transfer minicomputers will 
> be provided with 7--10 WWV and CHU channels received with redundant 
> auto-failover HF antennae, just in case some channels fail (and that is in 
> addition to redundant GPS and of course the set of redundant UPS-, solar-, 
> and generator-backed standards, which hopefully will grow to there being a 
> fused ensemble of two moder
 n Cs standards at any one time, rather than the current scheme of the 
VXI-based controller simply running one at a time in an auto-failover 
configuration).
> 
> -Ruslan
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Bob Camp]

Hi

The ground wave (hopefully) travels a shorter path. The gotcha comes in when
the phase shift is 180 degrees and you start nulling things out. That will play 
havoc 
on the “stuff” that works out the envelope shape for detecting the third pulse. 

Again, I didn’t design a from scratch receiver to do all this back in the 80’s. 
I just 
tuned my Austron over to another chain to see how it did and drew some 
conclusions. 

Bob

> On Feb 4, 2017, at 6:55 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> If I had not already calibrated the  local standard against a nearby chain …
>> no way to figure out which data was correct.  
> 
> Isn't the ground wave shorter and hence gets there sooner?  Couldn't you use 
> that to calibrate an uncalibrated local standard?
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Bob Camp]

Hi

The Russian system runs an incompatible pulse format. A “normal” Loran receiver 
pretty much pukes when you try to tune to the Russian chains. It also is a bit 
unclear
just how stable their system is timing wise. 

For timing you *need* ground wave. Anything that is more than 1,000 miles away 
is
not going to do much good in a timing system. To me this is one of the basic 
issues
with a eLoran system that only operates out of a single location. I’m happy 
with it if 
it’s in the north eastern part of the US. I’d be really bothered if the only 
transmit location 
was in Nevada …. 

Yes once upon a time I had data on the Iceland chain as received in Ohio. I did 
it more
as a “because I can” than anything else. There were periods that things looked 
~ok and
lots of gaps where they didn’t look very good at all. If I had not already 
calibrated the 
local standard against a nearby chain … no way to figure out which data was 
correct. 

Bob

> On Feb 4, 2017, at 3:05 AM, Ruslan Nabioullin  wrote:
> 
> On 02/03/2017 09:53 AM, Bob Camp wrote:
>> With reasonable gear, you can pick up the European Loran chains in
>> the US on a regular basis. You can also pick up the Russian system
>> that runs on the same frequency. The gotcha there is that you are
>> looking at “skywave” rather than “ground wave” signals to some
>> degree. That degrades their value for timing or for navigation. (Yes,
>> it is all a lot more complicated that than very simple / quick
>> summary).
> 
> Oh wow, I did not know that LORAN reception is adequate over such long 
> distances.  So Chayka is essentially compatible with Loran-C frequency 
> transfer receivers?  And is it still online?  If so, it could be used as a 
> fallback in the unfortunate case that eLORAN R&D projects in the US fail.
> 
> -Ruslan
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Bob Camp]

Hi

The spectrum is about what you would expect from a bunch of short pulses.

http://phk.freebsd.dk/loran-c/theoretical_spectrum/

Bob


> On Feb 3, 2017, at 4:40 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> the signal shows up over many 10’s of KHz of  bandwidth each side of 100
>> KHz.
> 
> What does the spectrum look like?  Is that even a reasonable question for 
> that sort of signal?
> 
> How well do typical old/analog spectrum analyzers work on that sort of 
> signal?  (as compared to modern digital/FFT versions)
> 
> How many samples do you need to get the full picture with a FFT?
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Bob Camp]

Hi

Loran C is a pulse based system. All transmitters world wide run on the same 
100 KHz frequency. The thing that 
distinguishes one transmission from another is the repetition rate of the 
signal. If you have a spectrum analyzer
and hook up a piece of wire near one of the transmitters, the signal shows up 
over many 10’s of KHz of 
bandwidth each side of 100 KHz. With reasonable gear, you can pick up the 
European Loran chains in the US
on a regular basis. You can also pick up the Russian system that runs on the 
same frequency. The gotcha there
is that you are looking at “skywave” rather than “ground wave” signals to some 
degree. That degrades their value
for timing or for navigation. (Yes, it is all a lot more complicated that than 
very simple / quick summary). 

Bob

> On Feb 3, 2017, at 1:20 AM, John Marvin  wrote:
> 
> I don't have a Loran receiver, and I live in Colorado. But I'd still like to 
> check late at night to see if I can see a signal on my SDR receiver. I tried 
> looking at old posts, and did some research online, but the best I can tell 
> is that Loran C (and I assume eLoran) is transmitted at around 100 Khz. 
> Anyone know precisely what frequency(s) are used by the Wildwood eLOran 
> station?
> 
> Regards,
> 
> John
> 
> 
> On 2/2/2017 11:59 AM, paul swed wrote:
>> Well this is nice almost a 2 month long test.
>> So if you thought about seeing if you could receive eLoran on your Loran C
>> receiver this is a good opportunity. With respect to the data channel
>> pretty sure none of the receivers we have know or care about it.
>> 
>> The Wildwood, NJ eLoran transmitter will be continuously broadcasting from
>> 0900 (EST) on 06 February 2017 through 1200 (EST) on 31 March 2017.
>> Wildwood will be broadcasting as 8970 Master and Secondary most of the time
>> but occasionally may operate at other rates.
>> 
>> 
>> 
>> Please note that the Loran Data Channel (LDC) will be undergoing testing
>> and may be unavailable or unreliable for short periods of time
>> 
>> from 06-10 February 2017.
>> 
>> Regards
>> Paul
>> WB8TSL
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Re: [time-nuts] distribution amp question + hp 59309A

[Bob Camp]

Hi

The gotcha with transformer coupled coax is keeping it terminated over a wide 
range of frequencies. If the coax is miss terminated
and the end of the cable is floating, you have a pretty good opportunity for 
noise to get into the system. Floating shields are also a 
pretty good way to get crosstalk. In many situations, isolation between outputs 
is a pretty big deal. 

Bob

> On Jan 28, 2017, at 12:29 PM, walter shawlee 2  wrote:
> 
> I notice that in the distribution amp being discussed at the moment,
> the BNC output connectors are grounded, and tied to the chassis,
> which in turn has a grounded emi line filter. this seems like an unavoidable 
> noise pathway to me.
> 
> I notice that some commercial amps are grounded, but more advanced and 
> transformer coupled units have floating connectors. it makes the most sense 
> to me to be floating, since this frees the return from line noise and 
> spurious, and avoids the significant problem of shifted AC voltages on the 
> return from distant units connected to the amp which are on other ac line 
> circuits.
> 
> What is the general feeling here about this issue?  I confess that if the amp 
> output is transformer coupled, I see exactly zero benefit in a grounded 
> connector as the feed from the amplifier.
> 
> Also on an unrelated topic, I found an HP 59309A HPIB clock on a forgotten 
> shelf and looked at it, and was surprised to see such a poor primary time 
> standard oscillator inside, just a 1Mhz crystal using a cmos buffer 
> oscillator. It can accept an external standard, but it did feel odd for a 
> device that is meant to provide coordinated system time to be so modestly 
> executed.  it's like an uncorrected PC desktop clock.
> 
> This same issue pops up in many hp/agilent counters, signal generators and 
> related objects. I have always been puzzled by the decision to make such 
> marginal instruments that have time/frequency as their primary parameter, 
> when so little additional effort would have dramatically improved them.  I do 
> get the concept of an external standard reference, but it's a pretty weak 
> argument for making a $5K generator or counter with poor performance.  Just 
> curious to know everybody's thoughts on this.
> 
> all the best,
> walter
> 
> -- 
> Walter Shawlee 2, President
> Sphere Research Corporation
> 3394 Sunnyside Rd.,  West Kelowna,  BC
> V1Z 2V4  CANADA  Phone: (250) 769-1834
> walt...@sphere.bc.ca
> WS2: We're all in one boat, no matter how it looks to you.
> Love is all you need. (John Lennon)
> But, that doesn't mean other things don't come in handy. (WS2)
> 
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Re: [time-nuts] Distribution amplifier (again!) - now mostly ok but has gain peaking

[Bob Camp]

Hi

The real question is: Do you have an application where < 100 ps matching 
matters? If so do you 
need to match both at the amplifier *and* at the ends of the cables? 

Other than a phased array radar, I can’t think of to many situations where the 
answer is yes …
Put another way, for the normal stuff we do, it is not a significant issue. If 
you know the offset
you can take it out in any calculations where it might matter. 

Bob

> On Jan 28, 2017, at 6:58 AM, Anders Wallin  
> wrote:
> 
> Hi all,
> I've been tinkering with another distribution amplifier design and made
> some measurements earlier this week.
> The goal is roughly 1:8 fan-out, gain of 0 dB, for good quality (Cs, maser,
> OCXO) 5 or 10 MHz signals in the range of maybe +0 dBm to +15 dBm - in a 1U
> form-factor.
> 
> Earlier I made an SMD version of the TADD-1 design [1] which showed about
> -156 dBc/Hz far-out phase-noise but was quite sensitive to external noise
> and required 12VDC power from a lead-acid battery as well as shielding in
> aluminium foil for a 'quiet' PN-spectrum.
> I then did some SPICE simulations [2] (never trust them without testing ;)
> which indicated ADA4899 would be a good op-amp. In practice the
> slew-rate/distortion was limiting and the AD4899 version didn't show better
> PN.
> 
> This new version is inspired by looking inside a 6502[3] - and in the
> mean-time I also measured and Ettus Octoclock [4] - but its performance
> isn't so exciting..
> 
> My current design is now here: https://goo.gl/photos/WB8fYd4jzba7nXH18
> So far my observations are:
> - phase noise around -162 dBc/Hz at 10 MHz
> - nice quiet PN-spectrum when unshielded and powered from lab-supplies
> - this probably means the supply-section with common-mode choke, BNX025
> filter and LT1963/LT3015 is working OK. I should probably build a
> 10Hz-100kHz LNA (e.g. [5]) to verify. I've used 2k@100MHz ferrites a lot
> and an RC-filter on all supply pins - maybe overkill?
> - an undesired feature is gain-peaking which increases from output ch1 to
> ch8, shown here: https://goo.gl/photos/6QkoKakSPDdT7Acj7
> I tried to improve it a bit by adding a 100pF cap at the start of the long
> trace that feeds the output stages, but some gain-peaking still remains:
> https://goo.gl/photos/qrkLzZ21ptcHxFsw6
> - reverse isolation around 120 dB
> - channel-to-channel isolation around 80 dB
> - at 10MHz 1dB compression between +14 and +15 dBm
> - IP3 perhaps +27dBm to +30 dBm.
> 
> Any ideas on how to deal with the long 'feeder-trace' that seems to be the
> cause of the gain-peaking?
> Anyway if not used at 100MHz perhaps my next version will have reduced BW
> where the feeder-trace is not an issue..
> Another issue is that the voltage regulators get quite hot when fed at
> +/-12V and producing +/-6V. They should probably be positioned as far away
> from the input/output amps and thermally disconnected if possible. I have a
> +/-12V AC/DC brick on order - but a DIY linear PSU producing e.g. +/-8VDC
> for the regulators might be better.
> 
> The picture gallery also shows a pulse distribution amp for 1PPS. It has an
> LT1711 comparator feeding an 74AC14 buffer with length-matched traces to
> 74AC04's at the outputs. So far my length-matching didn't give zero
> output-skew between the outputs - I see around 150-200ps skew which I tried
> to tune a bit with wires and 0R resistors - without very much success.. any
> ideas for improving this - or just leave it at 200ps skew?
> 
> cheers,
> Anders
> 
> [1]
> http://www.anderswallin.net/2015/12/frequency-distribution-amplifier-first-tests/
> [2]
> http://www.anderswallin.net/2015/12/frequency-distribution-amplifier-v2-simulations/
> [3]
> http://www.anderswallin.net/2016/02/symmetricom-6502-distribution-amplifier/
> [4]
> http://www.anderswallin.net/2016/09/ettus-octoclock-distribution-amplifier/
> [5] http://cds.linear.com/docs/en/application-note/an83f.pdf
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Bob Camp]

> On Jan 25, 2017, at 12:15 AM, Hal Murray  wrote:
> 
> way way way left.
> 
> Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In case 
> you don't recognize the name, he is one of the leaders of the LIGO project 
> that detected gravity waves about a year ago.
> 
> He's a good speaker with a neat topic.  He spent a lot of time giving credit 
> to other people.
> 
> One of the far-out future ideas he mentioned was collecting data on lots of 
> pulsars.  If you could get good enough data, maybe you could see gravity 
> waves wandering around the universe.  (Maybe leftover from the big bang.  I 
> didn't catch that part.)
> 
> The time scale is months or years.  Micro Hertz.  The unit for wavelength 
> would be light-years.

….. errr … would not that be the *right* end of the ADEV curve? …..:)

Back in the 1980’s these guys were after sub 1x10^-15 bumps over path 
distances like Earth to Jupiter. Not sure what they are after these days. 

Bob

> 
> How long will it be before we need a gravity-nuts list?
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Bob Camp]

Hi

The big gotcha in moving between these programs is porting the libraries. 
Without moving them over, you have very limited options when working in 
the “new” environment. 



Opened up the email this evening and *surprise* a discount coupon from 
Autodesk. Charge a lot as a “standard” price and then discount it 50%. 
Somehow this reminds me a lot of the local furniture sales  .. errr.. SALES …
errr..  Yes, it’s a brave new world.

Bob


> On Jan 24, 2017, at 2:12 PM, Hal Murray  wrote:
> 
> 
> ke9h.gra...@gmail.com said:
>> So a learning curve to get up on KiCad and, for me, an issue migrating ten
>> years personal library of component foot-prints. 
> 
> The Eagle files are store in simple text.  If there isn't already an Eagle to 
> KiCad translator, I'd expect one soon.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Bob Camp]

Hi


> On Jan 23, 2017, at 8:28 PM, Jim Pruitt  wrote:
> 
> Mike,  you are correct about Autodesk products being free to
> students/faculty/and staff with proof of status.  A college/university
> email would do that.
> 
> I retired from a medium size state university here in late spring.  My job
> there was to purchase, set up, install/administer software and hardware,
> and maintain some application servers including ones for Autodesk,
> Solidworks, Matlab, and Oracle Primavera.  I had 2 Autocad labs consisting
> of about 25 stations each.  We used Autodesk products because they were
> free to universities as long as it was in a teaching capacity.  For that
> reason facilities management could not use the educational version.
> Autodesk and the cad labs took up over 75% of my time so 2 labs kept me
> busy and I had 10 other pc labs to maintain on campus.  I assume that
> because the product was free to us we were on the bottom of the food chain
> as I ran into a bug with their product that cause our students to have to
> sit for 20 minutes before the license server would issue them a license.

Even if you pay >$100K in license fees a year, don’t count on fast solutions
for things like license server nonsense (or any other bug). We are not in any
way an Autodesk customer at work so that’s not a direct knock on them. It’s
more a knock on the industry as a whole. With the payments we *do* get
a solution of some sort eventually. Two weeks is a more likely time period 
than “later today” for most of them. That *is* better than the “maybe never”
time frame for unpaid support. It still is not what you need …..

Bob



> Keep in mind that classes only lasted 50 minutes!  Even though I hired a
> third party VAR (value added reseller) for cad tech support.  Education was
> all on their own so even my VAR could not help me resolve the problem.
> They did manage to give me one name at Autodesk that I could contact and
> push them from inside.  If it had not been for that I feel they never would
> have taken the problem seriously.  Even at that it took 2 months to get it
> figured out.  They did not fix the problem til the following year when a
> new version was released.  Prior to the product being offered free I could
> contact Autodesk and get support when needed.
> 
> In short,  Autodesk products are free to students and staff/faculty when
> used for educational purposes.  I had to resort to forums and other avenues
> to get tech support.
> 
> Good luck.
> 
> Jim Pruitt
> 
> 
> On Mon, Jan 23, 2017 at 4:56 PM, Mike Suhar  wrote:
> 
>> Many companies are trying to jump on the subscription band wagon.  It is a
>> way to keep a steady flow of income.  Unfortunately,  hobbyists are left
>> out in the cold.   I have version 7.5 with the hobbyist license.  I just
>> tried to get 7.7 but the download pulls in version 8.0.  I did not install
>> it.
>> 
>> If you are not using the software on a regular basis I assume  you could
>> go  with the monthly subscription for a month then drop it.  Pick up again
>> a few months later when you start another project and need more than the
>> freeware capabilities.
>> 
>> Looks like they have a student version but the way I read it you have to
>> actually be a student enrolled in an education institution.  I assume they
>> require some form of proof.
>> 
>> Mike
>> W8RKO
>> 
>> -Original Message-
>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of John
>> Ackermann N8UR
>> Sent: Monday, January 23, 2017 17:14
>> To: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] Autodesk Eagle -- maybe they're listening
>> 
>> Autodesk just sent a follow-up to my "new price model unacceptable"
>> complaint a few days ago.  It looks like they are going to upgrade the
>> "Standard" subscription ($100/year) to support 4 layer boards up to 160
>> cm2, which I think matches the current standard version capabilities.
>> Here's a thread from the Autodesk forum:
>> 
>> http://forums.autodesk.com/t5/eagle-forum/a-path-forward-
>> for-the-make-license-a-step-up-for-standard/td-p/6823182
>> 
>> This is effective with the next release, which is supposed to be out in a
>> couple of weeks.  (In the meantime, I've made sure to download every flavor
>> of installer for version 7.7.0, just in case...)
>> 
>> 
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Re: [time-nuts] Thermal effects on cables

[Bob Camp]

Hi

Back a long time ago the people I was working with spent time looking
at the impedance of a variety of coax cables. The data they came up
with on some varieties of cable would suggest that cable is not an outlier…

Bob


> On Jan 23, 2017, at 3:08 PM, jimlux  wrote:
> 
> On 1/23/17 9:16 AM, Bob Camp wrote:
>> Hi
>> 
>> Nothing is ever simple if you dig deep enough:
>> 
>> http://www.jensign.com/RG58U/
>> 
>> http://www.cliftonlaboratories.com/the_curious_case_of.htm
>> 
> 
> here's my guess on the curious case cable: it was mismarked by accident at 
> the factory (e.g. 93 ohm coax, marked as 50 because someone forgot to push 
> the button on the marking machine), and dumped in the scrap bin, and then 
> sold by someone who bought the surplus and just read the markings.
> 
> Or, even sold as a whole spool, likely at a discount, to a "knowledgeable 
> buyer" who was willing to take it, mismarkings and all.
> 
> 
> 
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Re: [time-nuts] Thermal effects on cables

[Bob Camp]

Hi

Nothing is ever simple if you dig deep enough:

http://www.jensign.com/RG58U/

http://www.cliftonlaboratories.com/the_curious_case_of.htm

Bob

> On Jan 23, 2017, at 10:13 AM, REEVES Paul  
> wrote:
> 
> Hi David,
> 
> Surely the impedance of the cable is only affected by the ratio of the inner 
> conductor and outer conductor diameters modified by the internal dielectric 
> constant, nothing to do with the frequency of operation. You might well have 
> problems converting the larger diameters down to a suitable size for the 
> connectors at the higher frequencies though
> I thought that the HP cabling for the 8510 series VNAs was air spaced but I 
> might well be wrong - I just tried not to damage them :-)
> Regards,
> 
> Paul Reeves
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dr. David 
> Kirkby (Kirkby Microwave Ltd)
> Sent: 23 January 2017 13:26
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Thermal effects on cables
> 
> On 13 January 2017 at 06:52, Ole Petter Ronningen 
> wrote:
> 
>> Hi, all
>> 
>> The question of phase shifts in cables pops up every now and then on 
>> this list - I stumbled across a good table of measured phase shifts 
>> with temperature in different cable types in this paper:
>> http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_
>> PresentationWSchaefer.pdf
>> that I though would be of interest to others.
>> 
>> 
> I've like to know how VNA cables compare. They are expensive enough - a 
> couple of cables around 600 mm long (24") for my VNA are over $5000. They are 
> much larger diameter than normal cables, but much more flexible too.
> The construction is obviously very different. Since mine are designed for use 
> to 26.5 GHz, the internal diameter of the outer conductor can be no more than 
> a couple of mm, yet the overall cable has a diameter of about 15 mm.
> 
> Dave
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Re: [time-nuts] purpose of time of day display units

[Bob Camp]

Hi

Trying to troubleshoot those racks *without* being able to see the timing is
harder than if you can. This gizmo should trigger at the top of the minute. 
Did it trigger? That’s much easier to catch if you can see the minute 
transition. 
If the rack goes down, it needs to be back up fast…..

Bob


> On Jan 23, 2017, at 2:36 AM, Robert Atkinson via time-nuts 
>  wrote:
> 
> One must remember the original use of these displays was displaying IRIG time 
> either distributed from a master clock, locally generated or from a recording 
> (tape) They long predate GPS. There are more sophisticated units that include 
> controls for the tape recorder so you could auto search to a certain time. 
> Multiple displays could be used for locally generated time, time received 
> from a remote site by fixed line or radio and time from data or video 
> recorders.I have a number of them and one sits above my GPStar as the LCD on 
> the GPStar is hard to read from across the workshop and it lets me have time 
> available while showing timing or satellite  status on the GPS. Just picked 
> up 3 more (RAPCO 104 anyone have a manual for these) at the weekend.
> Robert G8RPI.
> 
>  From: Bob Bownes 
> To: Discussion of precise time and frequency measurement  
> Sent: Sunday, 22 January 2017, 18:33
> Subject: Re: [time-nuts] purpose of time of day display units
> 
> 
> #5) Everyone likes blinkenlights. 
> 

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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi


> On Jan 21, 2017, at 2:52 PM, Charles Steinmetz  wrote:
> 
> jimlux wrote:
> 
>> I forgot to watch (actually, I knew it was today, but I thought
>> it would be on this afternoon, not at 7AM)..
>> 
>> (and, I'll get a call from management on Monday.. uh, Jim, about that
>> interview)
> 
> LOL
> 
> Try this: 
> 

That gets me to a quick intro to the episode and a link to watch the whole 
thing. The watch
the whole thing link sends me off to another episode entirely :(

Bob

> 
> Best regards,
> 
> Charles
> 
> 
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi

So what we are all now scrambling to find a copy of is season 3, episode 62 
originally aired 1/21/2017 of Innovation Nation. 

Bob

> On Jan 21, 2017, at 2:09 PM, jimlux  wrote:
> 
> On 1/21/17 10:24 AM, steve heidmann via time-nuts wrote:
>> WoW . I don't know if I'm the first nut to see this but it was probably our 
>> own Jim Lux I just saw on CBS's Innovation Nation
> 
> It was.. I forgot to watch (actually, I knew it was today, but I thought it 
> would be on this afternoon, not at 7AM)..
> 
> I hope it came out ok.  You film these things months and months ago, and they 
> edit A LOT...
> 
> For all I know, it came out as "Jim believes that aliens built the pyramids 
> to prevent global warming, and when Napoleon's army started shooting 
> artillery at them, it was the beginning of the end"
> 
> (and, I'll get a call from management on Monday.. uh, Jim, about that 
> interview)
> 
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi



> On Jan 21, 2017, at 10:25 AM, jimlux  wrote:
> 
> On 1/20/17 7:10 PM, Bob Camp wrote:
>> Hi
>> 
>> There are several other materials that you can make crystal resonators out 
>> of that
>> are piezo electric. Some of them can give you much higher Q. This comes with 
>> a whole
>> raft of other issues. Langesite is one of the more common materials you see 
>> people
>> playing with. It is common enough that I’ve actually played with it myself.  
>> The simple
>> answer is that when you look at cost, Q, and stability (aging, ADEV, 
>> temperature) —
>> it is tough to beat quartz. If you have a few hundred thousand dollars, you 
>> can play
>> with great big chunks of Sapphire. Toss in a bit of this and a bit of that 
>> and you can get a
>> pretty amazing oscillator. That device may (or may not) be < $1,000,000 
>> depending
>> on how you do the accounting and how many parts you spread the costs over.
> 
> 
> would not a true time nut grow their own sapphire?

Or at the very least spend some quality time digging a 100 lb lump up out 
of the Australian outback ….

> 
> Realistically, isn't it all about the crystal lattice.. SiO2 vs Al2O3 vs 
> Lanthanum Gallium Silicate vs Lithium Niobate
> 
> WHat makes a "good" material?  I would think the ability to grow a very 
> uniform crystal is part of it, but are certain crystal forms better than 
> others?

Indeed you need a “well grown” crystal and figuring out how to grow 
them without adding a bunch of stress, contamination, and imperfections
in the lattice is a very big deal. Past that, for Q you get into the acoustic 
loss properties of the material. Some materials are less lossy than others. 
It is no different than picking a microwave dielectric in that regard. Some 
of the fun and games involved is measuring the acoustic properties of
all these materials. 

Bob

> 
> 
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Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Bob Camp]

Hi

The interesting point about “who said what” is that Autodesk people stated
*after* the acquisition that the Eagle  license model would not change … 
That’s one of the reasons I’d like to wait a bit and see what those same 
people say now.

Bob

> On Jan 21, 2017, at 9:43 AM, paul swed  wrote:
> 
> What can I add to this thats not been said.
> This is how software is moving and it did start with Autodesk who sacked
> there original license model for the subscription approach and is making a
> ton of money that way. Its annuity. A gift that keeps on giving. Meanwhile
> they add bloat-ware for the sake of trying to appear to add some value
> I can go on but as all of you have observed it is what it is. Sitting back
> and griping will not change it. Its a major corporate direction change
> especially if a company was acquired. Its really not going to change. When
> a company is acquired what ever had been stated positions no longer matter.
> Its not the same company any longer, just the same name.
> So exploring alternates as you are all doing is great and helpful.
> Regards
> Paul
> WB8TSL
> 
> On Fri, Jan 20, 2017 at 4:42 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> 
>>> On Jan 20, 2017, at 12:44 PM, Chris Albertson 
>> wrote:
>>> 
>>> It could be what they are doing is purposely trying to "blow off"
>>> their less desirable customers.
>>> 
>>> I explained this to someone I know who was upset at a large bank she
>>> deals with.  She said she would move "all her money out of the bank"
>>> all $5,000 of it.I explain to her that was EXACTLY what the bank
>>> wanted and the reason for the policies she experienced.   Small
>>> customers with $5K deposits are not profitable.So Autodesk is
>>> selling subscriptions for $500 and offering "one on one" sport.
>> 
>> The last time they played this game they found that reducing the
>> subscriber base 1000:1
>> at $500 a year was not as good as 10:1 at $50 a year.  That’s why I
>> suggest that people
>> wait a bit and see what happens over the next few months. Eagle does not
>> have what it takes
>> to compete as a PCB program for the big guys. There is no great big block
>> of licenses at the Fortune
>> 500 to milk in this case. The user base is large. It is made up of the
>> small, price sensitive guys. Each
>> time the Eagle license stuff has been fiddled in the past, it’s been a
>> disaster because of that.
>> 
>> The Eagle “per customer” cost is nearly zero ( unlike a bank ). It’s
>> really all about how much money they
>> bring in each year. Their costs scale more on a per bug …. errr … per
>> feature basis rather
>> than by the customer (at least for the hobby customer). They will charge
>> what they can as long as
>> people keep signing up. If nobody signs up … they will adjust.
>> 
>> Bob
>> 
>>> 
>>> Apple has a neat business model too.   They have like about 18% of the
>>> world's cellphone market but make the MAJORITY of the profit.  What
>>> they do is take the one in five most profitable customers.
>>> 
>>> Maybe Autodesk is looking to do the same thing, take only the most
>>> rich customers and let the others go elsewhere.
>>> 
>>> In the end nicad might be the best for the hobby market.
>>> 
>>> Autodesk is looking to offer the integrated solution where the PCB and
>>> case that it lives in are designed together by a team that is
>>> geographically distributed.
>>> 
>>> On Fri, Jan 20, 2017 at 8:58 AM, Bob Camp  wrote:
>>>> Hi
>>>> 
>>>> I completely agree that their spin at acquisition and the reality of
>> what just came out
>>>> is completely amazing. They said they would never do this and that.
>> What they are doing
>>>> is exactly what they said they would not do.
>>>> 
>>>> It’s a rare board that I do in < 4 layers. It’s also quite normal to
>> have designs above
>>>> 160 CM^2. If I have 4 layers, there *will* be signals on all those
>> layers. That puts me
>>>> squarely in the $500 / yr subscription. A month ago that put me in a
>> perpetual license
>>>> that I paid < 1/2 that for.
>>>> 
>>>> It is not just that the cost has gone up. A number of license
>> “categories” have vanished.
>>>> The free version is still there, and just as useless for what I do.
>> That’s about the only
>>>> one that is rational at this point.
>>>> 
>

Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Bob Camp]

Hi

Fusion 360 has the same sort of “slurp it up” and “net connection” 
requirements. Anything 
you do is (at least potentially) not exclusively yours. Fine for a basement. As 
you point out
a bit nuts for any corporation. My guess is that there is or will be some sort 
of corporate server
connection to take care of the issue. At leas in Fusion, there is no obvious 
way to make that
happen. It’s a complicated program so who knows what may be lurking in there 
somewhere ….

Bob

> On Jan 20, 2017, at 9:45 PM, Mark Sims  wrote:
> 
> I'd say 80% of the outside design work I do have little ditties in the 
> contracts that say NO development to be done on net connected systems.  New 
> Eagle requires a net connection to keep working.  Also the EULA seems to say 
> they can slurp your designs at will and ship them off to who knows who/where. 
>   Autocad seems to be totally un-aware of the rabid IP protection that 
> companies require these days.
> 
> I don't know how many sales Eagle has made off my recommendations / work (I 
> suspect quite a few)...  but that revenue is going to stop.
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi

There are several other materials that you can make crystal resonators out of 
that
are piezo electric. Some of them can give you much higher Q. This comes with a 
whole
raft of other issues. Langesite is one of the more common materials you see 
people
playing with. It is common enough that I’ve actually played with it myself.  
The simple
 answer is that when you look at cost, Q, and stability (aging, ADEV, 
temperature) — 
it is tough to beat quartz. If you have a few hundred thousand dollars, you can 
play
with great big chunks of Sapphire. Toss in a bit of this and a bit of that and 
you can get a 
pretty amazing oscillator. That device may (or may not) be < $1,000,000 
depending 
on how you do the accounting and how many parts you spread the costs over. 

Bob

> On Jan 20, 2017, at 12:57 PM, Alex Pummer  wrote:
> 
> once upon the time there was an other crystal material -- NOT quartz ! --  
> the Russian came up with it, perhaps Bernd [Neubig] remembers on that, what 
> happened to that story?
> that crystal could be run at higher drive level, therefore it would be 
> possible to make some better oscillators
> 73
> KJ6UHN
> Alex
> 
> 
> 
> On 1/20/2017 8:38 AM, Bob Camp wrote:
>> Hi
>> 
>> If you think about it, current through the crystal is at least as important 
>> as
>> “drive level”. They are related by the crystal resistance. As the overtone
>> goes up, the resistance (in general) goes up. There are size constrained
>> designs where other things get in the way of this. There are also tricks
>> that might be used to degrade the fundamental.
>> 
>> Since the resistance is higher at the 5th than at the fundamental, 1 mw of 
>> crystal
>> dissipation (drive level) is going to be less current through the crystal. 
>> At some
>> (possibly a bit removed) point that gets you less current into your buffer 
>> amplifier at
>> a given impedance level. Less current / same impedance gets you to worse 
>> signal
>> to noise broadband.
>> 
>> Is this really that big a deal? As always … that depends. ADEV usually 
>> degrades
>> as drive goes up. Phase noise gets better. At some point this or that 
>> crystal explodes
>> (the electrodes fly off). It is uncommon to get to the damage level on a 
>> crystal. You
>> normally massage the design in the tradeoff region.
>> 
>> Bob
>> 
>>> On Jan 19, 2017, at 7:31 PM, Scott Stobbe  wrote:
>>> 
>>> Is there any reason why you wouldn't be able to run the same drive level on
>>> say the fifth overtone versus the fundamental? I would guess at 100 MHz it
>>> may be 3rd or 5th, or are they fundamental?
>>> 
>>> The comments one drivelevel are simply based on snr, larger signal with
>>> same noise, better snr
>>> 
>>> On Thu, Jan 19, 2017 at 7:06 PM Bob Camp  wrote:
>>> 
>>>> Hi
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>>> On Jan 19, 2017, at 3:03 PM, Scott Stobbe 
>>>> wrote:
>>>> 
>>>>> Wouldn't crystal drive level be one of the important specifications for
>>>> far
>>>> 
>>>>> out phase noise?
>>>> 
>>>> 
>>>> It would, but you can get the same floor at 10 MHz as you can get at 100
>>>> MHz.
>>>> 
>>>> 
>>>> 
>>>> Bob
>>>> 
>>>> 
>>>> 
>>>>> On Thu, Jan 19, 2017 at 1:33 PM, Bob Camp  wrote:
>>>>>> HI
>>>>>> A lot of your evaluation of the term “better” will depend on your
>>>> intended
>>>> 
>>>>>> use. One of the limits on phase noise
>>>>>> is the thermal noise floor. Because of that, starting at a higher
>>>>>> frequency will always give you an edge on broadband
>>>>>> phase noise. ADEV / short term stability is linked to the Q of your
>>>>>> resonator. In a quartz crystal, maximum Q is
>>>>>> roughly proportional to frequency. The other limit on Q is blank
>>>> geometry
>>>> 
>>>>>> (size). One other limit is practicality -
>>>>>> is a $250,000 OCXO that is 1 cubic meter in size appropriate for your
>>>>>> application? The answer to that one is
>>>>>> universally - NO :) Somewhere along the line of larger size and cost,
>>>>>> other technologies make more sense.
>>>>>> So, if better = phase noise floor, 100 MHz is better than 10 MHz. If
>&g

Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Bob Camp]

Hi


> On Jan 20, 2017, at 12:44 PM, Chris Albertson  
> wrote:
> 
> It could be what they are doing is purposely trying to "blow off"
> their less desirable customers.
> 
> I explained this to someone I know who was upset at a large bank she
> deals with.  She said she would move "all her money out of the bank"
> all $5,000 of it.I explain to her that was EXACTLY what the bank
> wanted and the reason for the policies she experienced.   Small
> customers with $5K deposits are not profitable.So Autodesk is
> selling subscriptions for $500 and offering "one on one" sport.

The last time they played this game they found that reducing the subscriber 
base 1000:1 
at $500 a year was not as good as 10:1 at $50 a year.  That’s why I suggest 
that people 
wait a bit and see what happens over the next few months. Eagle does not have 
what it takes
to compete as a PCB program for the big guys. There is no great big block of 
licenses at the Fortune
500 to milk in this case. The user base is large. It is made up of the small, 
price sensitive guys. Each
time the Eagle license stuff has been fiddled in the past, it’s been a disaster 
because of that. 

The Eagle “per customer” cost is nearly zero ( unlike a bank ). It’s really all 
about how much money they 
bring in each year. Their costs scale more on a per bug …. errr … per feature 
basis rather
than by the customer (at least for the hobby customer). They will charge what 
they can as long as 
people keep signing up. If nobody signs up … they will adjust. 

Bob

> 
> Apple has a neat business model too.   They have like about 18% of the
> world's cellphone market but make the MAJORITY of the profit.  What
> they do is take the one in five most profitable customers.
> 
> Maybe Autodesk is looking to do the same thing, take only the most
> rich customers and let the others go elsewhere.
> 
> In the end nicad might be the best for the hobby market.
> 
> Autodesk is looking to offer the integrated solution where the PCB and
> case that it lives in are designed together by a team that is
> geographically distributed.
> 
> On Fri, Jan 20, 2017 at 8:58 AM, Bob Camp  wrote:
>> Hi
>> 
>> I completely agree that their spin at acquisition and the reality of what 
>> just came out
>> is completely amazing. They said they would never do this and that. What 
>> they are doing
>> is exactly what they said they would not do.
>> 
>> It’s a rare board that I do in < 4 layers. It’s also quite normal to have 
>> designs above
>> 160 CM^2. If I have 4 layers, there *will* be signals on all those layers. 
>> That puts me
>> squarely in the $500 / yr subscription. A month ago that put me in a 
>> perpetual license
>> that I paid < 1/2 that for.
>> 
>> It is not just that the cost has gone up. A number of license “categories” 
>> have vanished.
>> The free version is still there, and just as useless for what I do. That’s 
>> about the only
>> one that is rational at this point.
>> 
>> So yes, I’m at least as bothered by this as anybody else. What I would 
>> suggest is to
>> take a deep breath, sit back, yell at them a bit (along with everybody else 
>> that has
>> a license) and see what they do. It is abundantly clear that they have a 
>> major disconnect
>> between this and what they have said. There is a lot of explaining for them 
>> to do. Part of that
>> could easily be another couple license categories. I’m certainly in no hurry 
>> to switch
>> packages.
>> 
>> Right now Fusion 360 is something I use a LOT  more than I use Eagle. This 
>> week (month .. year)
>> it is free for me to do that. Why is Fusion free to a basement guy and Eagle 
>> pay?
>> That’s not at all clear. Fusion is buggy as can be. Eagle needs some 
>> updates. Both
>> have a lot of development $$$ that they will be sucking up. Yes that has to 
>> get paid
>> for. It’s not clear that a revenue stream based on hobbyists paying $500 a 
>> year
>> is rational. My guess is Autodesk will figure that out. They may abandon the 
>> whole
>> basement thing, they may not …. we’ll see.
>> 
>> Bob
>> 
>> 
>>> On Jan 19, 2017, at 10:52 PM, Richard (Rick) Karlquist 
>>>  wrote:
>>> 
>>> Off topic, but probably a lot of disgrunted Eagle users on this list.
>>> Its official, you will now have to pay $500 per year for a
>>> professional license from Autodesk.  The spin meistering of the
>>> announcement would make George Orwell proud.  I don't see any way they
>>> can keep me from just using the license I currently own, a

Re: [time-nuts] PN/AM and 1.5Hz spur from frequency doubling?

[Bob Camp]

Hi

I would bet that the spur moving is an indicator of either the 25 MHz 
transmitter carrier or
modulator drifting in frequency. My guess is that the Maser does not drift :)

Bob

> On Jan 20, 2017, at 12:22 PM, Anders Wallin  
> wrote:
> 
> I made some progress with this issue today.
> It turns I was using a 75Ohm cable at some point (doh!) which caused a
> 'forest' of spurs far out. Possibly our other maser has a faulty/cut cable
> which behaves similarly.
> The final fix was to turn off our 25 MHz radio time-code transmitter which
> was causing the strong close-in spur at around 1.5 Hz. It uses a modified
> DCF77 code where it transmits full power AM-modulated 25MHz carrier for 0,
> 100ms or 200ms at the start of each second.
> 
> Here are PN plots of the 5MHz maser signal, same signal through 75ohm
> reflective cable to the doubler, and through a 50ohm cable
> to the doubler which solves the far-out spurs, and finally turning off the
> radio transmitter. The result is now close to the +6dBc/Hz expected for a
> doubler.
> https://goo.gl/photos/qKKvg3SfE1XKxtq17
> as a time-series of residual phase the switchoff of the time-code
> transmitter looks like so:
> https://goo.gl/photos/jNVJK2kj1kGUkSVd9
> 
> Finally I tried it with the transmitter on, but reduced coupling into the
> lab by disconnecting a few monitoring-cables. Strangely this shifts the
> spur even closer in (close to 1Hz now) and reduces the amplitude as expected
> https://goo.gl/photos/jG6rxfuC8R2QKchM6
> 
> What makes frequency doublers especially sensitive to this kind of
> interference? The 25MHz carrier is phase-locked to better than 1e-12 to our
> masers, so there can't reasonably be a 1-1.5Hz offset in the carrier
> frequency. What is the interaction? (5th harmonic of 5Mhz mixes with 25MHz?)
> 
> Anders
> 
> 
> On Fri, Jan 20, 2017 at 11:06 AM, Anders Wallin > wrote:
> 
>> Thanks for all the comments so far.
>> I will try the doubler with another quieter source, and try removing
>> various potential noise-sources and exchanging cables...
>> 
>> I have now uploaded a few more images of the same data to the shared album
>> linked in my earlier post.
>> 
>> Anders
>> 
>> On Thu, Jan 19, 2017 at 10:39 PM, Bill Byrom  wrote:
>> 
>>> I see spurs at 50 Hz and harmonics, which I assume are from the power
>>> line at your location. This might be due to an oscillation in the power
>>> supply regulator, leading to nonlinear regulator operation and
>>> feedthrough of power line ripple. For example, low dropout regulators
>>> can sometimes oscillate when an additional ceramic bypass capacitor is
>>> added due to decreased phase margin in the feedback loop. It's also
>>> possible that there is too much ripple before the regulator and you are
>>> exceeding the dropout voltage, or that the regulator is going in and out
>>> of an overcurrent condition. Many odd things may happen if the power
>>> supply regular isn't working properly.
>>> 
>>> 
>>> --
>>> 
>>> Bill Byrom N5BB
>>> 
>>> 
>>> 
>>> 
>>> 
 _
>>> 
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>>> 
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>>> 
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>>> 
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>>> 
>> 
>> 
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Re: [time-nuts] Thunderbolt Harmonics

[Bob Camp]

Hi

> On Jan 20, 2017, at 11:22 AM, Tom Miller  wrote:
> 
> 
> - Original Message - From: "jimlux" 
> To: 
> Sent: Friday, January 20, 2017 8:34 AM
> Subject: Re: [time-nuts] Thunderbolt Harmonics
> 
> 
>> On 1/19/17 8:48 PM, Rhys D wrote:
>>> Thanks for the detailed post Bill,
>>> 
>>> I'm learning a lot here!
>>> So the spectrum analyser is indeed a "trap for young players"
>>> As you guessed, it is a Siglent SSA3000X series analyzer.
>>> 
>>> I just looked at the same signal again with varied attenuations dialed in
>>> on the instrument (I am using an external 20dB attenuator from minicircuits
>>> as well)
>>> 
>>> Here is what I saw:
>>> 
>>> Attenuation  -  Fundamental - 1st Harmonic - 2nd Harmonic
>>> 15 dB  -   11.40 dB  - 49.13 dB- 51.12 dB
>>> 20 dB  -   11.40 dB  - 48.84 dB- 56.48 dB
>>> 25 dB  -   11.28 dB  - 48.32 dB- 49.15 dB
>>> 
>>> I guess these numbers mean I can't really trust what I can see on the
>>> instrument screen?
>> 
>> Actually, that's fairly good.  Most spectrum analyzers are good to about 1/2 
>> dB with a moderate level signal (your fundamental).
>> 
>> The variation you're seeing is probably some combination of:
>> 1) the mismatch between the source impedance and the spectrum analyzer input 
>> impedance - the latter of which almost certainly changes with attenuation 
>> setting
>> 2) The calibration of the step attenuator.
>> 3) maybe some change in harmonic production in the SA front end... in your 
>> case, though the harmonic levels go DOWN as the attenuation is decreased, 
>> which is the opposite of what happens with harmonics
>> 
> 
> If you want to see the levels of the harmonics you should notch out the 
> fundamental.

….. and use a notch filter that does not miss-terminate the output amplifier 
(as most notch filters do …) 

Bob

> 
> Regards,
> Tom
> 
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi

If you think about it, current through the crystal is at least as important as 
“drive level”. They are related by the crystal resistance. As the overtone 
goes up, the resistance (in general) goes up. There are size constrained 
designs where other things get in the way of this. There are also tricks 
that might be used to degrade the fundamental. 

Since the resistance is higher at the 5th than at the fundamental, 1 mw of 
crystal
dissipation (drive level) is going to be less current through the crystal. At 
some 
(possibly a bit removed) point that gets you less current into your buffer 
amplifier at
a given impedance level. Less current / same impedance gets you to worse signal 
to noise broadband. 

Is this really that big a deal? As always … that depends. ADEV usually degrades
as drive goes up. Phase noise gets better. At some point this or that crystal 
explodes 
(the electrodes fly off). It is uncommon to get to the damage level on a 
crystal. You
normally massage the design in the tradeoff region.

Bob

> On Jan 19, 2017, at 7:31 PM, Scott Stobbe  wrote:
> 
> Is there any reason why you wouldn't be able to run the same drive level on
> say the fifth overtone versus the fundamental? I would guess at 100 MHz it
> may be 3rd or 5th, or are they fundamental?
> 
> The comments one drivelevel are simply based on snr, larger signal with
> same noise, better snr
> 
> On Thu, Jan 19, 2017 at 7:06 PM Bob Camp  wrote:
> 
>> Hi
>> 
>> 
>> 
>> 
>> 
>>> On Jan 19, 2017, at 3:03 PM, Scott Stobbe 
>> wrote:
>> 
>>> 
>> 
>>> Wouldn't crystal drive level be one of the important specifications for
>> far
>> 
>>> out phase noise?
>> 
>> 
>> 
>> It would, but you can get the same floor at 10 MHz as you can get at 100
>> MHz.
>> 
>> 
>> 
>> Bob
>> 
>> 
>> 
>>> 
>> 
>>> On Thu, Jan 19, 2017 at 1:33 PM, Bob Camp  wrote:
>> 
>>> 
>> 
>>>> HI
>> 
>>>> 
>> 
>>>> A lot of your evaluation of the term “better” will depend on your
>> intended
>> 
>>>> use. One of the limits on phase noise
>> 
>>>> is the thermal noise floor. Because of that, starting at a higher
>> 
>>>> frequency will always give you an edge on broadband
>> 
>>>> phase noise. ADEV / short term stability is linked to the Q of your
>> 
>>>> resonator. In a quartz crystal, maximum Q is
>> 
>>>> roughly proportional to frequency. The other limit on Q is blank
>> geometry
>> 
>>>> (size). One other limit is practicality -
>> 
>>>> is a $250,000 OCXO that is 1 cubic meter in size appropriate for your
>> 
>>>> application? The answer to that one is
>> 
>>>> universally - NO :) Somewhere along the line of larger size and cost,
>> 
>>>> other technologies make more sense.
>> 
>>>> 
>> 
>>>> So, if better = phase noise floor, 100 MHz is better than 10 MHz. If
>> 
>>>> better = ADEV, 5 MHz in a large package is
>> 
>>>> likely better than 100 MHz. Indeed these are only two variables. There
>> are
>> 
>>>> *many* others you could look at.
>> 
>>>> 
>> 
>>>> Lots of fun
>> 
>>>> 
>> 
>>>> Bob
>> 
>>>> 
>> 
>>>> 
>> 
>>>> 
>> 
>>>>> On Jan 19, 2017, at 7:13 AM, Charles Steinmetz 
>> 
>>>> wrote:
>> 
>>>>> 
>> 
>>>>> Chris wrote:
>> 
>>>>> 
>> 
>>>>>> I have always wondered why we build our "standard" with such a low
>> 
>>>>>> frequency.   Why not a 100MHz GPSDO?   Why 10MHz
>> 
>>>>> 
>> 
>>>>> Quartz crystals work better at lower frequencies, predominantly because
>> 
>>>> they have higher Q.  10MHz was chosen because it is low enough for
>> 
>>>> excellent performance but high enough to be directly useful (since an
>> 
>>>> accident of biology gave us ten fingers, we've created a base-10 world
>> and
>> 
>>>> powers of 10 are favored in almost everything).
>> 
>>>>> 
>> 
>>>>> In prior times, 5MHz crystals held this position, and before that,
>> 
>>>> 1MHz.  There is a good argument even today that the best 2.5MHz or 5MHz
>> 
>>

Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Bob Camp]

Hi

I completely agree that their spin at acquisition and the reality of what just 
came out
is completely amazing. They said they would never do this and that. What they 
are doing
is exactly what they said they would not do. 

It’s a rare board that I do in < 4 layers. It’s also quite normal to have 
designs above 
160 CM^2. If I have 4 layers, there *will* be signals on all those layers. That 
puts me
squarely in the $500 / yr subscription. A month ago that put me in a perpetual 
license 
that I paid < 1/2 that for. 

It is not just that the cost has gone up. A number of license “categories” have 
vanished. 
The free version is still there, and just as useless for what I do. That’s 
about the only
one that is rational at this point. 

So yes, I’m at least as bothered by this as anybody else. What I would suggest 
is to 
take a deep breath, sit back, yell at them a bit (along with everybody else 
that has
a license) and see what they do. It is abundantly clear that they have a major 
disconnect
between this and what they have said. There is a lot of explaining for them to 
do. Part of that
could easily be another couple license categories. I’m certainly in no hurry to 
switch
packages. 

Right now Fusion 360 is something I use a LOT  more than I use Eagle. This week 
(month .. year)
it is free for me to do that. Why is Fusion free to a basement guy and Eagle 
pay? 
That’s not at all clear. Fusion is buggy as can be. Eagle needs some updates. 
Both
have a lot of development $$$ that they will be sucking up. Yes that has to get 
paid 
for. It’s not clear that a revenue stream based on hobbyists paying $500 a year 
is rational. My guess is Autodesk will figure that out. They may abandon the 
whole 
basement thing, they may not …. we’ll see.

Bob


> On Jan 19, 2017, at 10:52 PM, Richard (Rick) Karlquist 
>  wrote:
> 
> Off topic, but probably a lot of disgrunted Eagle users on this list.
> Its official, you will now have to pay $500 per year for a
> professional license from Autodesk.  The spin meistering of the
> announcement would make George Orwell proud.  I don't see any way they
> can keep me from just using the license I currently own, at least
> on the OS's it supports.  (Parenthetically, like many users, I
> am also digging in my heels in terms of staying at Windows 7).
> 
> Still, the question arises:  are there any affordable alternatives?
> Don't have to be entirely free.  I am looking for any trends out
> there as to what tool will attract a critical mass of users in
> the future.  There is strength in numbers.
> 
> Comments?
> 
> Rick N6RK
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Re: [time-nuts] Thunderbolt Harmonics

[Bob Camp]

Hi

> On Jan 19, 2017, at 11:48 PM, Rhys D  wrote:
> 
> Thanks for the detailed post Bill,
> 
> I'm learning a lot here!
> So the spectrum analyser is indeed a "trap for young players"
> As you guessed, it is a Siglent SSA3000X series analyzer.
> 
> I just looked at the same signal again with varied attenuations dialed in
> on the instrument (I am using an external 20dB attenuator from minicircuits
> as well)
> 
> Here is what I saw:
> 
> Attenuation  -  Fundamental - 1st Harmonic - 2nd Harmonic
> 15 dB  -   11.40 dB  - 49.13 dB- 51.12 dB
> 20 dB  -   11.40 dB  - 48.84 dB- 56.48 dB
> 25 dB  -   11.28 dB  - 48.32 dB- 49.15 dB
> 
> I guess these numbers mean I can't really trust what I can see on the
> instrument screen?

Like any instrument, there are limits to it’s performance. There are ways to 
check if you are at these limits. It’s not a matter of trust. It’s a matter of 
trust but verify ….

Bob

> 
> By the way, I should just you know that I am not trying to solve a specific
> timing problem here, I'm more using it as learning opportunity and making
> sure that my setup is the best it can be.
> 
> Thanks again for the input.
> 
> On 20 January 2017 at 12:26, Bill Byrom  wrote:
> 
>> You can't trust such low harmonic spurious measurements from a  spectrum
>> analyzer unless you know how the spurs change with input level. The
>> second harmonic spur created in an amplifier or mixer inside the
>> spectrum analyzer input will typically increase by 2 dB for every 1 dB
>> of input level increase. Anytime you see a frequency converting RF
>> component (such as the mixer in the input of a spectrum analyzer), it is
>> nonlinear and will generate harmonics and intermodulation products. All
>> you need to do is to keep the input level low enough so that the
>> distortion products generated in the analyzer are below the signals you
>> are measuring. The best and easiest technique is to increase the input
>> attenuation by the smallest step available (such as 5 dB or 10 dB) and
>> checking how the spurious components change.
>> ** If the harmonic or other spurious signal is coming from an external
>> source, it should not change as the input attenuation changes.
>> ** If the harmonic or other spurious signal is generated inside the
>> analyzer, it should change relative to the fundamental signal as the
>> input attenuation changes.
>> ** I'm talking about the harmonics or other spurious signals relative to
>> the fundamental frequency being displayed. If you remove the input
>> signal and still see the spur, it's a residual spur created inside the
>> analyzer unrelated to the input signal.
>> 
>> 
>> If you graph fundamental signal displayed amplitude vs changing input
>> level, you will typically see the following for spurious signals created
>> by most mixers or amplifiers:
>> (1) Fundamental signal = slope of 1
>> 
>> (2) Second harmonic signal = slope of 2
>> 
>> (3) Third order intermodulation (sum or different frequencies caused by
>>mixing of two signals) = slope of 3
>> 
>> 
>> For more background, see:
>> 
>> https://en.wikipedia.org/wiki/Third-order_intercept_point
>> 
>> 
>> 
>> If that is a SiglentSSA3000X series analyzer, here are the spurious
>> specifications from the datasheet:
>> ** Second harmonic distortion: -65 dBc (above 50 MHz input with
>> preamplifier off)
>> 
>> 
>> Note that the second harmonic distortion is only specified at 50 MHz
>> input and above and at a -30 dBm input power level with the preamplifier
>> off. For comparison, here are the specifications of a Tektronix RSA507A
>> portable spectrum analyzer. Disclosure: I work for Tektronix.
>> ** Second harmonic distortion: - 75 dBc (above 40 MHz input,
>> preamplifier OFF)
>> ** Second harmonic distortion: - 60 dBc (above 40 MHz input,
>> preamplifier ON)
>> 
>> 
>> I'm sure that the reason for a lower limit on the second harmonic
>> specification is that the results are worse at lower frequencies. So
>> it's quite possible that the harmonics you see are mainly coming from
>> the spectrum analyzer input mixer or preamplifier. As I suggested
>> earlier, try lowering the input level by 5 or 10 dB  and see if the
>> harmonics go down linearly.
>> --
>> 
>> Bill Byrom N5BB
>> 
>> 
>> 
>> 
>> 
>> On Tue, Jan 17, 2017, at 08:40 PM, Rhys D wrote:
>> 
>>> Hi all,
>> 
>>> 
>> 
>>> Before I start, let me say I'm rather a newbie at this sort of
>>> stuff so
>>> please be gentle.
>> 
>>> 
>> 
>>> I was looking at the output of my Trimble Thunderbolt GPSDO and
>>> was rather
>>> surprised to see really "loud" harmonics in there. ~ 60dB down
>>> from the
>>> 10Mhz signal.
>> 
>>> 
>> 
>>> Can anyone here shed some light on what I am seeing here?
>> 
>>> Surely this isn't what it is supposed to look like? Should I be
>>> trying to
>>> filter these before going to my distribution amplifier?
>> 
>>> 
>> 
>>> Thanks for any light you can shed.
>> 
>>> 
>> 
>>> R
>> 
>>> 
>> 
>>> 
>> 
>>> 

Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi

> On Jan 19, 2017, at 2:42 PM, Bryan _  wrote:
> 
> Wouldn't designing circuitry and PCB's be easier with 10Mhz vs 100Mhz? Maybe 
> not so much now but then.

Design in general might be a bit easier at the lower frequency “way back when”. 
I’ve never run into 
it as an issue or consideration since the mid 1960’s though. 

Bob

> 
> 
> -=Bryan=-
> 
> 
> 
> From: time-nuts  on behalf of Charles Steinmetz 
> 
> Sent: January 19, 2017 4:13 AM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] 10MHz to 25MHz
> 
> Chris wrote:
> 
>> I have always wondered why we build our "standard" with such a low
>> frequency.   Why not a 100MHz GPSDO?   Why 10MHz
> 
> Quartz crystals work better at lower frequencies, predominantly because
> they have higher Q.  10MHz was chosen because it is low enough for
> excellent performance but high enough to be directly useful (since an
> accident of biology gave us ten fingers, we've created a base-10 world
> and powers of 10 are favored in almost everything).
> 
> In prior times, 5MHz crystals held this position, and before that, 1MHz.
>  There is a good argument even today that the best 2.5MHz or 5MHz
> crystals are better than the best 10MHz crystals, but not by enough to
> make 2.5MHz or 5MHz standards popular any longer.
> 
> One lonely data point, which proves nothing:  My best crystal oscillator
> is a Symmetricom clone of the double-oven HP 10811s (it came out of an
> HP GPSDO, so apparently HP at one time used them interchangeably with
> the 10811).  That OCXO uses a 5MHz crystal and a frequency doubler to
> produce its 10MHz output.
> 
> Best Regards,
> 
> Charles
> 
> 
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> 
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Re: [time-nuts] Detector Matching

[Bob Camp]

Hi

Not sure this is on topic for the group, but here’s the simple answer:

Your diode detector does not present a constant load as the power goes from 
-50 dbm to 0 dbm. If you have a matching circuit, it can only work at one power 
level. 
In addition, you have frequency effects. 

The simple answer is not to match the detector over the whole power range. You 
provide
an adequate match to the rest of the system by other means (possibly an 
isolator, maybe something 
else).

Bob

> On Jan 19, 2017, at 4:00 PM, Mohammad-Hadi Sohrabi  
> wrote:
> 
> Hello,
> I am new to this amazing community. Here is my question; I am designing a
> matching circuit for an RF (envelop) detector, which is simply a diode.
> However, I cannot make the matching stable for various powers at BW=0.5 GHz
> around center frequency of 15 GHz. Matching moves away quickly from 50 ohms
> by changing the power from -50 dBm to 0 dBm.
> Any suggestion or guide would be appreciated.
> 
> Thanks,
> Mohammad
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

> On Jan 19, 2017, at 3:03 PM, Scott Stobbe  wrote:
> 
> Wouldn't crystal drive level be one of the important specifications for far
> out phase noise?
> 
> On Thu, Jan 19, 2017 at 1:33 PM, Bob Camp  wrote:
> 
>> HI
>> 
>> A lot of your evaluation of the term “better” will depend on your intended
>> use. One of the limits on phase noise
>> is the thermal noise floor. Because of that, starting at a higher
>> frequency will always give you an edge on broadband
>> phase noise. ADEV / short term stability is linked to the Q of your
>> resonator. In a quartz crystal, maximum Q is
>> roughly proportional to frequency. The other limit on Q is blank geometry
>> (size). One other limit is practicality -
>> is a $250,000 OCXO that is 1 cubic meter in size appropriate for your
>> application? The answer to that one is
>> universally - NO :) Somewhere along the line of larger size and cost,
>> other technologies make more sense.
>> 
>> So, if better = phase noise floor, 100 MHz is better than 10 MHz. If
>> better = ADEV, 5 MHz in a large package is
>> likely better than 100 MHz. Indeed these are only two variables. There are
>> *many* others you could look at.
>> 
>> Lots of fun
>> 
>> Bob
>> 
>> 
>> 
>>> On Jan 19, 2017, at 7:13 AM, Charles Steinmetz 
>> wrote:
>>> 
>>> Chris wrote:
>>> 
>>>> I have always wondered why we build our "standard" with such a low
>>>> frequency.   Why not a 100MHz GPSDO?   Why 10MHz
>>> 
>>> Quartz crystals work better at lower frequencies, predominantly because
>> they have higher Q.  10MHz was chosen because it is low enough for
>> excellent performance but high enough to be directly useful (since an
>> accident of biology gave us ten fingers, we've created a base-10 world and
>> powers of 10 are favored in almost everything).
>>> 
>>> In prior times, 5MHz crystals held this position, and before that,
>> 1MHz.  There is a good argument even today that the best 2.5MHz or 5MHz
>> crystals are better than the best 10MHz crystals, but not by enough to make
>> 2.5MHz or 5MHz standards popular any longer.
>>> 
>>> One lonely data point, which proves nothing:  My best crystal oscillator
>> is a Symmetricom clone of the double-oven HP 10811s (it came out of an HP
>> GPSDO, so apparently HP at one time used them interchangeably with the
>> 10811).  That OCXO uses a 5MHz crystal and a frequency doubler to produce
>> its 10MHz output.
>>> 
>>> Best Regards,
>>> 
>>> Charles
>>> 
>> 
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi


> On Jan 19, 2017, at 3:03 PM, Scott Stobbe  wrote:
> 
> Wouldn't crystal drive level be one of the important specifications for far
> out phase noise?

It would, but you can get the same floor at 10 MHz as you can get at 100 MHz.

Bob

> 
> On Thu, Jan 19, 2017 at 1:33 PM, Bob Camp  wrote:
> 
>> HI
>> 
>> A lot of your evaluation of the term “better” will depend on your intended
>> use. One of the limits on phase noise
>> is the thermal noise floor. Because of that, starting at a higher
>> frequency will always give you an edge on broadband
>> phase noise. ADEV / short term stability is linked to the Q of your
>> resonator. In a quartz crystal, maximum Q is
>> roughly proportional to frequency. The other limit on Q is blank geometry
>> (size). One other limit is practicality -
>> is a $250,000 OCXO that is 1 cubic meter in size appropriate for your
>> application? The answer to that one is
>> universally - NO :) Somewhere along the line of larger size and cost,
>> other technologies make more sense.
>> 
>> So, if better = phase noise floor, 100 MHz is better than 10 MHz. If
>> better = ADEV, 5 MHz in a large package is
>> likely better than 100 MHz. Indeed these are only two variables. There are
>> *many* others you could look at.
>> 
>> Lots of fun
>> 
>> Bob
>> 
>> 
>> 
>>> On Jan 19, 2017, at 7:13 AM, Charles Steinmetz 
>> wrote:
>>> 
>>> Chris wrote:
>>> 
>>>> I have always wondered why we build our "standard" with such a low
>>>> frequency.   Why not a 100MHz GPSDO?   Why 10MHz
>>> 
>>> Quartz crystals work better at lower frequencies, predominantly because
>> they have higher Q.  10MHz was chosen because it is low enough for
>> excellent performance but high enough to be directly useful (since an
>> accident of biology gave us ten fingers, we've created a base-10 world and
>> powers of 10 are favored in almost everything).
>>> 
>>> In prior times, 5MHz crystals held this position, and before that,
>> 1MHz.  There is a good argument even today that the best 2.5MHz or 5MHz
>> crystals are better than the best 10MHz crystals, but not by enough to make
>> 2.5MHz or 5MHz standards popular any longer.
>>> 
>>> One lonely data point, which proves nothing:  My best crystal oscillator
>> is a Symmetricom clone of the double-oven HP 10811s (it came out of an HP
>> GPSDO, so apparently HP at one time used them interchangeably with the
>> 10811).  That OCXO uses a 5MHz crystal and a frequency doubler to produce
>> its 10MHz output.
>>> 
>>> Best Regards,
>>> 
>>> Charles
>>> 
>> 
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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

HI

A lot of your evaluation of the term “better” will depend on your intended use. 
One of the limits on phase noise
is the thermal noise floor. Because of that, starting at a higher frequency 
will always give you an edge on broadband
phase noise. ADEV / short term stability is linked to the Q of your resonator. 
In a quartz crystal, maximum Q is 
roughly proportional to frequency. The other limit on Q is blank geometry 
(size). One other limit is practicality - 
is a $250,000 OCXO that is 1 cubic meter in size appropriate for your 
application? The answer to that one is 
universally - NO :) Somewhere along the line of larger size and cost, other 
technologies make more sense. 

So, if better = phase noise floor, 100 MHz is better than 10 MHz. If better = 
ADEV, 5 MHz in a large package is 
likely better than 100 MHz. Indeed these are only two variables. There are 
*many* others you could look at. 

Lots of fun 

Bob 



> On Jan 19, 2017, at 7:13 AM, Charles Steinmetz  wrote:
> 
> Chris wrote:
> 
>> I have always wondered why we build our "standard" with such a low
>> frequency.   Why not a 100MHz GPSDO?   Why 10MHz
> 
> Quartz crystals work better at lower frequencies, predominantly because they 
> have higher Q.  10MHz was chosen because it is low enough for excellent 
> performance but high enough to be directly useful (since an accident of 
> biology gave us ten fingers, we've created a base-10 world and powers of 10 
> are favored in almost everything).
> 
> In prior times, 5MHz crystals held this position, and before that, 1MHz.  
> There is a good argument even today that the best 2.5MHz or 5MHz crystals are 
> better than the best 10MHz crystals, but not by enough to make 2.5MHz or 5MHz 
> standards popular any longer.
> 
> One lonely data point, which proves nothing:  My best crystal oscillator is a 
> Symmetricom clone of the double-oven HP 10811s (it came out of an HP GPSDO, 
> so apparently HP at one time used them interchangeably with the 10811).  That 
> OCXO uses a 5MHz crystal and a frequency doubler to produce its 10MHz output.
> 
> Best Regards,
> 
> Charles
> 

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Re: [time-nuts] 10MHz to 25MHz

[Bob Camp]

Hi

What are you going to use the 25 MHz for? Will it drive any sort of radio? If 
so, cleaning up the phase
noise of the GPSDO is a *very* good idea. With a PLL, you can *subtract* noise. 
With a multiplier you 
can only *add* noise. The narrow bandwidth PLL combined with a low nose VCXO is 
your friend in this case. 

I would take the process one step further. I’d lock up a 100 MHz VCXO to the 10 
MHz. Then you can get
100, 50, 25, and 20 MHz outputs. The 100 MHz is the key if you want to head up 
into the microwave 
region. 

Bob

> On Jan 18, 2017, at 8:40 PM, Loren Moline WA7SKT  wrote:
> 
> Are you talking about locking the 50MHz VCXO to my 10 MH. Standard? I want 
> the 25MHz to be from my 10MHz OCXO which is my station standard which will 
> locked to GPS eventually.
> 
> Loren WA7SKT
> 
> 
> 
> 
> On Wed, Jan 18, 2017 at 4:01 PM -0800, "Richard (Rick) Karlquist" 
> mailto:rich...@karlquist.com>> wrote:
> 
> 
> A better and easier way is to phase lock a crystal oscillator.
> I would use a 50 MHz VCXO and divide the output by 2 to get a
> 25 MHz square wave.
> 
> Rick N6RK
> 
> On 1/18/2017 10:28 AM, Loren Moline WA7SKT wrote:
>> Hello,
>> 
>> I am looking for a good X5 multiplier to use to generate a 25MHz signal from 
>> my 10MHz OCXO. I want to divide by 2 and multiply by 5 with a bandpass 
>> filter in the output and then a 3.3 volt 25MHz signal out.
>> 
>> 
>> Maybe someone has better ways?
>> 
>> 
>> Loren Moline  WA7SKT
>> 
>> Member: Pacific Northwest VHF Society and ARRL
>> Member: Hearsat Satellite Monitoring Group.  www.uhf-satcom.com
>> Member: CVARS-Chehalis Valley Amateur Radio Society
>> Starchat IRC: Channel = #hearsat
>> RF Electronics: Starchat IRC: Channel = #rfelectronics
>> Grid: CN86mr
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Re: [time-nuts] Thunderbolt Harmonics

[Bob Camp]

Hi

> On Jan 18, 2017, at 1:08 PM, jimlux  wrote:
> 
> On 1/18/17 8:56 AM, Bob Camp wrote:
>> HI
>>> 
>>> the first time we ran the test (using a Keysight 33622 signal
>>> generator) we saw significant 2nd and 3rd harmonics (50-60 dB down,
>>> but easily detectable).  A quick review of the data sheet.. Oh, the
>>> signal generator spec is only -43 dBc for frequencies above 10
>>> MHz.
>> 
>> So even a pretty expensive signal generator still has “loud”
>> harmonics if judged at the -60 dbc level ….
>> 
> that's actually an inexpensive ($7.4k) function generator (with good 
> performance for a function generator that does a lot of stuff, except 
> generate chirps at the right rate)..
> 
> A $8k Keysight N9310 is -30dBc
> 
> A R+S SMA100 specs -30dBc  (actually does better)
> 
> A $23k Keysight 8663D specs -55dBc (at 1 GHz)
> 
> 
> 
> 
>>> 
>>> Another case where low harmonic content is when doing two tone IMD
>>> tests - if the sources have significant harmonic content, you might
>>> be seeing intermod between the harmonics of the source, rather than
>>> intermods between the fundamental of the source.
>> 
>> Which is one of the reasons a lot of IMD test setups have a variety
>> of filters in them.
>> 
>> 
>> These also are a pretty common item on eBay, at ham fest, and in your
>> typical RF junk box. 10.7 MHz IF filter cans can fairly easily be
>> tuned down to 10 MHz to custom roll bandpass filters.
> 
> Yeah, but it's easier (cheaper if you're paying for labor) just to buy a box 
> of 10 filters at $30/each and stack them

Be *very* careful cascading those Min-Circuits filters without putting some 
sort of isolation between them. You can get all
sorts of wonky results as the reactances in one mis-terminates the reactances 
in another.

Bob


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Re: [time-nuts] PN/AM and 1.5Hz spur from frequency doubling?

[Bob Camp]

Hi

Without seeing the circuit involved it’s a bit tough to guess all of the 
possible
things that might be happening. One branch leads off to things like the circuit
it’s self oscillating and creating the spur. Sub branches involve oscillation 
in 
a regulator at low frequency vs RF oscillation somewhere else. Another branch 
heads in the direction  of a loose cable running around the shop with a bunch 
of 10 MHz on it. There are many branches ….

Bob

> On Jan 18, 2017, at 11:13 AM, Anders Wallin  
> wrote:
> 
> I'm seeing +20-30 dBc/Hz of excess AM/PN, as well as a strong 1.5 Hz spur
> created by frequency doubling from 5 MHz to 10 MHz.
> https://goo.gl/photos/GFx9tQoxrSmyzUQo8
> The input amplitude to the doubler should be just above the recommended 11
> dBm.
> What's going on??
> 
> thanks!
> Anders
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Re: [time-nuts] Thunderbolt Harmonics

[Bob Camp]

HI

> On Jan 18, 2017, at 9:44 AM, jimlux  wrote:
> 
> On 1/18/17 4:33 AM, Artek Manuals wrote:
>> R
>> 
>> Is what your seeing a harmonic (2nd? 3rd?) or a spur i.e what frequency
>> is the "harmonic" ?
>> 
>> How are you measuring this ? (Spectrum analyzer ? make/model?)
>> 
>> More importantly and at the risk of displaying my naivety, what is the
>> application that you are using the 10MHz source to feed and why if this
>> harmonic is 60db down (or even only 40db down, the quoted spec) why
>> would one care? What is the predicted error you will get in your
>> application as a result?
>> 
> 
> One application that needs low harmonic content is where you are measuring 
> the harmonic generating (or lack thereof) of a downstream component.
> 
> I have an application where we're measuring the performance of a RF chain 
> followed by a digitizer.  An easy test is to feed in a nice sine wave (at a 
> frequency that is NOT a submultiple of the samplerate) and look for harmonics 
> in the power spectrum of the sampled data stream.
> 
> the first time we ran the test (using a Keysight 33622 signal generator) we 
> saw significant 2nd and 3rd harmonics (50-60 dB down, but easily detectable). 
>  A quick review of the data sheet.. Oh, the signal generator spec is only -43 
> dBc for frequencies above 10 MHz.

So even a pretty expensive signal generator still has “loud” harmonics if 
judged at the -60 dbc level ….

> 
> Another case where low harmonic content is when doing two tone IMD tests - if 
> the sources have significant harmonic content, you might be seeing intermod 
> between the harmonics of the source, rather than intermods between the 
> fundamental of the source.

Which is one of the reasons a lot of IMD test setups have a variety of filters 
in them.

> 
> For 10 MHz, you can get minicircuits filters for 10.7 MHz that are fairly 
> wideband and work pretty well... about 20-30 dB of harmonic suppression per 
> filter I'd use the low pass flavor
> 
> SBP-10.7
> loss at 20MHz is 26.84
> loss at 40MHz is 41.22
> loss at 50MHz is 46
> est loss at 30 is 35?
> 
> SLP-10.7
> loss at 10 is 0.65 spec
> loss at 20 is 31.35 spec  measured -33
> loss at 30 measured -60
> loss at 34 is 47.26 spec
> loss at 40 measured -77
> loss at 67.5 is 69.85 spec

These also are a pretty common item on eBay, at ham fest, and in your typical 
RF junk box. 10.7 MHz IF filter cans can fairly
easily be tuned down to 10 MHz to custom roll bandpass filters. 

Bob


> 
> 
> 
> Yeah, they might have a significant tempco, but you're running all this stuff 
> in an underground lair with small temperature variations, right? It only 
> looks like a small volcano from the outside.
> 
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Re: [time-nuts] How to create a super Rb standard

[Bob Camp]

Hi

You would need to redesign the Rb to work in a vacuum. There is a lot involved
in doing that. They depend on the air inside the package to properly operate the
heating in the physics package. Different parts of the package are at different 
temperatures. Without the air cooling the temperature offsets could not be 
properly 
maintained. 

There are a *lot* of differences between the GPS Rb’s and the ones we buy on
eBay. The fact that they operate in pretty far down the list of significant 
differences.
The most simple answer to “why” the Rb is better is that the design requirements
on the two standards were different, as were the design teams. Coming up with 
an Rb with better short term stability is the way that all worked out. That 
short 
term stability is better than other large cell Rb designs, but not by a crazy 
amount. 
How much better it is depends a lot on which large cell Rb design you compare 
to.
It also depends a bit on which specific unit you are looking at.

All that said, space benign is indeed a pretty quiet environment. It certainly 
does 
help a bit if you operate there. There is also data on the GPS Rb’s that show 
them
doing quite well on the ground. So no, it’s not all space, but space does not 
hurt
their performance. 

Bob

> On Jan 18, 2017, at 12:23 AM, Li Ang <379...@qq.com> wrote:
> 
> Hi
> I am wondering if anyone tried to put a Rb unit into a vacuum container. And 
> how much the performance is improved? Someone told me that's why the Rb 
> clocks are more stable than Cs clocks on the GPS satellites.
> 
> LiAng
> 
> ---Original---
> From: "Bob Camp"
> Date: 2017/1/17 21:20:23
> To: "Discussion of precise time and frequency 
> measurement";"Perry Sandeen";
> Subject: Re: [time-nuts] How to create a super Rb standard
> 
> 
> Hi
> 
> Since the physics package in the small Rb’s is different than the stuff in 
> the large units, 
> you have some basic limits on what you can do to improve them. The main 
> things people
> have done are to modify them to turn off the temperature compensation and 
> replace it
> with some sort of precision controlled thermal enclosure. Pressure 
> compensation is a good
> idea on any of these parts (large or small). How much your particular unit 
> benefits is a 
> “that depends” sort of thing.
> 
> Bob
> 
>> On Jan 16, 2017, at 10:24 PM, Perry Sandeen via time-nuts 
>>  wrote:
>> 
>> 
>> List
>> It looks like their is as infinitely small chance of being able to get 5065.
>> So what can be done with the telco Rb's (mine are analog tuned) to wring the 
>> best possible performance from them? Sooper Duper power supplies, Peltier 
>> (sp) cooling modules?
>> Regards,
>> Perrier
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Re: [time-nuts] Thunderbolt Harmonics

[Bob Camp]

Hi

If you look at the FCC transmitter regs, -60 dbc is “ok” for many transmitters. 

Bob

> On Jan 17, 2017, at 9:40 PM, Rhys D  wrote:
> 
> Hi all,
> 
> Before I start, let me say I'm rather a newbie at this sort of stuff so
> please be gentle.
> 
> I was looking at the output of my Trimble Thunderbolt GPSDO and was rather
> surprised to see really "loud" harmonics in there. ~ 60dB down from the
> 10Mhz signal.
> 
> Can anyone here shed some light on what I am seeing here?
> Surely this isn't what it is supposed to look like? Should I be trying to
> filter these before going to my distribution amplifier?
> 
> Thanks for any light you can shed.
> 
> R
> 
> 
> ​
> <10MhzRef.png>___
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Re: [time-nuts] time-nuts Digest, Vol 150, Issue 36

[Bob Camp]

Hi

At least at the “it stops working” level, Rb’s are not as sensitive to residual 
magnetic fields as what you 
describe on H-masers. The scrap guys routinely mangle the shielding around 
small Rb’s and the parts
still work when we receive them. 

On another level, the answer is (of course) yes. Any residual field  will have 
an effect on a magnetically tuned 
frequency source. That would definitely drive the material selection for 
anything in or near the physics package. 

Bob

> On Jan 17, 2017, at 9:53 AM, John Ponsonby  wrote:
> 
> Re: Low Cost Temperature sensor
> The ZNI1000 sensor is based on nickel. As such it must be ferromagnetic. It 
> would thus be absolutely unacceptable in an H-maser where every single small 
> item inside the magnetic shields must be tested for residual ferromagnetism. 
> If ferromagnetism is detectable the item is unacceptable. This applies to 
> every small screw, thermistor, varactor etc. Unfortunately manufacturers of 
> thermistors etc don't state what the wires are made of and it may vary 
> between batches of the same nominal item. This is one of the problems with 
> making H-masers. Though nominally made of copper and zinc, common brass often 
> shows residual ferro magnetism because it is "recovered" metal and is  
> contaminated with iron. That brass must never be used in a magnetic 
> instrument have been known for a very long time. I don't know off-hand if 
> Caesium or Rubidium standards are as sensitive in this regard as H-masers. I 
> guess I could find out from Vanier and Audoin.
> John P
> 
> 
> On 17 Jan 2017, at 14:14, time-nuts-requ...@febo.com wrote:
> 
>> Send time-nuts mailing list submissions to
>>  time-nuts@febo.com
>> 
>> To subscribe or unsubscribe via the World Wide Web, visit
>>  https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> or, via email, send a message with subject or body 'help' to
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>> 
>> You can reach the person managing the list at
>>  time-nuts-ow...@febo.com
>> 
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of time-nuts digest..."
>> 
>> 
>> Today's Topics:
>> 
>>  1. Re: Looking for GPS module (Exactime ET6000/Datum 9390-6000)
>> (ziggy9+time-n...@pumpkinbrook.com)
>>  2. Re: wifi with time sync (David)
>>  3. Re: wifi with time sync (David)
>>  4. Looking for GPS module (Exactime ET6000/Datum 9390-6000
>> (Mark Sims)
>>  5. HP 5061A/B Cesium tube conundrum (cdel...@juno.com)
>>  6. Re: HP 5061A/B Cesium tube conundrum (paul swed)
>>  7. Fluke/Pendulum Counters - Rubidium Timebase (Ed Palmer)
>>  8. Re: Fluke/Pendulum Counters - Rubidium Timebase (Magnus Danielson)
>>  9. Looking for GPS module (Exactime ET6000/Datum 9390-6000)
>> (Mark Sims)
>> 10. How to create a super Rb standard (Perry Sandeen)
>> 11. Low CostTemperature sensor (Perry Sandeen)
>> 12. Who has a hm H Maser? (Perry Sandeen)
>> 13. Who has a hm H Maser? (Perry Sandeen)
>> 14. TICC update? (Scott Newell)
>> 15. Re: Low CostTemperature sensor (Bill Hawkins)
>> 16. Re: Looking for GPS module (Exactime ET6000/Datum 9390-6000)
>> (ziggy9+time-n...@pumpkinbrook.com)
>> 17. Re: Low CostTemperature sensor (Jason Ball)
>> 18. Re: Low CostTemperature sensor (Tom Miller)
>> 19. Re: Low CostTemperature sensor (Charles Steinmetz)
>> 20. Re: How to create a super Rb standard (Bob Camp)
>> 21. Re: Low CostTemperature sensor (Scott Stobbe)
>> 22. Re: TICC update? (John Ackermann N8UR)
>> 
>> 
>> --
>> 
>> Message: 1
>> Date: Mon, 16 Jan 2017 13:17:32 -0500
>> From: ziggy9+time-n...@pumpkinbrook.com
>> To: Discussion of precise time and frequency measurement
>>  
>> Subject: Re: [time-nuts] Looking for GPS module (Exactime ET6000/Datum
>>  9390-6000)
>> Message-ID: 
>> Content-Type: text/plain; charset=utf-8
>> 
>> I did see that one, but I am hoping I can procure something that isn't
>> from an overseas surplus scrapper. If I can't find anything else, then I
>> guess it's my only choice. Unfortunately, the Heol folks don't have
>> anything to offer here either. It's not a WNRO problem, as the week and
>> date are correct. Even if not, that doesn't affect the GPSDO, only the
>> timecode generation.
>> 
>> Thanks for replying and the eBay pointer.
>> 
>> On 01/16/2017 02:56 AM, Mike Cook wrote:
>>> If your friends don’t have a CM3 spare, there is

Re: [time-nuts] How to create a super Rb standard

[Bob Camp]

Hi

Since the physics package in the small Rb’s is different than the stuff in the 
large units, 
you have some basic limits on what you can do to improve them. The main things 
people
have done are to modify them to turn off the temperature compensation and 
replace it
with some sort of precision controlled thermal enclosure. Pressure compensation 
is a good
idea on any of these parts (large or small). How much your particular unit 
benefits is a 
“that depends” sort of thing.

Bob

> On Jan 16, 2017, at 10:24 PM, Perry Sandeen via time-nuts 
>  wrote:
> 
> 
> List
> It looks like their is as infinitely small chance of being able to get 5065.
> So what can be done with the telco Rb's (mine are analog tuned) to wring the 
> best possible performance from them? Sooper Duper power supplies, Peltier 
> (sp) cooling modules?
> Regards,
> Perrier
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Re: [time-nuts] time transfer over wifi

[Bob Camp]

Hi

Ok, that’s a pretty good paper. At least it shows data and digs into the 
details. 
It also would lead one to believe that a “Time Nuts” grade sync system might 
be a hackable sort of thing …… hmmm…..Given how highly integrated these
WiFi chip sets have become, that probably is a fantasy. 

Bob

> On Jan 15, 2017, at 11:10 AM, Scott Stobbe  wrote:
> 
> Here is a ti app note with timestamping hardware wl8 but ordinary ap's with
> no special protocol just timestamping the beacon frame.
> 
> http://www.ti.com/lit/an/swaa162a/swaa162a.pdf
> 
> On Sun, Jan 15, 2017 at 10:06 AM jimlux  wrote:
> 
>> Returning to the OP
>> 
>> "A TimeSync certification program will appear later this year, but
>> 
>> semiconductor firms will have to create new Wi-Fi chips including the
>> 
>> feature."
>> 
>> 
>> 
>> so this "new thing" will be hardware of some TBD form.
>> 
>> https://www.wi-fi.org/discover-wi-fi/wi-fi-timesync
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> But more interesting to time-nuts, I think, is how do you do it without
>> 
>> the new hardware.
>> 
>> 
>> 
>> http://www.cse.msu.edu/~glxing/docs/WizSync.pdf
>> 
>> says, in part:
>> 
>> 
>> 
>> 802.11  requires  all  APs  to  broadcast  periodic beacon frames that
>> 
>> carry important management information (e.g., supported  rates  and
>> 
>> security  settings).  The  default  beacon period is 102.4 ms, which is
>> 
>> rarely changed on production APs. ...However, as defined in 802.11,
>> 
>> whether a  beacon  frame  is  delayed  or  not,  the  subsequent  beacon
>> 
>> frame shall always  be scheduled at the undelayed  nominal beacon interval.
>> 
>> 
>> 
>> so this is the "use a 1pps, but throw out outliers" kind of strategy...
>> 
>> 
>> 
>> And there would need to be some sort of measurement of the AP's timing
>> 
>> error - they make the assumption that the timing of the beacons is
>> 
>> driven by a clock with max 25ppm error (as required by the 802.11 std),
>> 
>> although they've measured <5ppm normally
>> 
>> 
>> 
>> Ultimately, they got on the order of 0.1 0.2 ms.
>> 
>> 
>> 
>> 
>> 
>> That's a few orders of magnitude worse than "microsecond", but it's also
>> 
>> an interesting read.
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> an older presentation (2006) might be useful
>> 
>> 
>> http://www.ieee802.org/1/files/public/docs2006/avb-stanton-wifi-timesync-intro-060613.pdf
>> 
>> 
>> 
>> discusses 802.11v
>> 
>> 
>> 
>> there's been a lot of stuff on time sync/distribution over 802.11 links
>> 
>> for the last decade.. maybe this CES announcement is more about "we at
>> 
>> WiFi alliance are ready to market it".   Has anyone gone through the
>> 
>> 802.11 standards list recently?  It might well be that the standard is
>> 
>> already there.
>> 
>> 
>> 
>> 802.11aa says "Amendment 2: MAC Enhancements for Robust Audio Video
>> 
>> Streaming" in the description...   although that might just be things
>> 
>> like QoS and access control-digital rights management
>> 
>> 
>> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

The push behind this is whole house audio. These guys want to be able to set up 
WiFi
speakers / mic's all through a home and get proper audio imaging in each room. 
They likely
also want to use it to figure out which mic you are talking to using time of 
arrival. They very 
much want to do this in real environments (300 WiFi nets in the building). 
Since they want to
roll it out that way, it’s got to be cheap and fairly robust. They need their 
gizmo to work with 
the infrastructure you already have.

Bob

> On Jan 15, 2017, at 9:35 AM, jimlux  wrote:
> 
> On 1/15/17 6:27 AM, Bob Camp wrote:
>> Hi
>> 
>> 
>> Again, this is why the interest in “how the heck did they accomplish it?
>> With the claim of microsecond level performance, they must have run
>> into all these issues.
> 
> or is it "with these two specific WiFi adapters in this specific environment, 
> we were able to achieve microsecond level performance, and who knows if it's 
> generalizable"
> 
> 
> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

I’d be surprised if a laptop running on wall power and doing a variety of low 
level
traffic every second is throttling the chip set. It *is* doing something weird 
and 
that certainly is one candidate. I’m not quite as concerned with the *why* the 
bumps 
occur (though I am curious). I’m more interested in the fact that they are 
really
enormous (compared to other delays). How they do microsecond timing with them
in the mix is the big question. 

Bob

> On Jan 15, 2017, at 8:33 AM, Tim Shoppa  wrote:
> 
> Bob, I think you are pushing me in this direction, but it was my conclusion
> before this discussion even began.
> 
> Most consumer WiFi devices will quiesce the WiFi chipset between major
> consumer-initiated usages for battery savings, so it's not surprising to
> see a good amount of random variation in ping times when done from a laptop.
> 
> Some apps that try to do timing over internet do a "wake-up call" of the
> interface first, and then do the timing. I don't know if this was ever
> added to ntpd but I work with all sorts of UDP applications that have to do
> application-level things like wake-up calls or application-layer keepalives
> to bring VPN tunnels "Back to life" (otherwise the first UDP packets are
> dropped).
> 
> Tim N3QE
> 
> 
> 
> On Sat, Jan 14, 2017 at 2:02 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> 
>>> On Jan 14, 2017, at 1:38 PM, Chris Albertson 
>> wrote:
>>> 
>>> On Sat, Jan 14, 2017 at 7:46 AM, Bob Camp  wrote:
>>> 
>>>> Hi
>>>> 
>>>> Ok, what I see is that every few hours, I get a “rogue delay” on a
>> single
>>>> ping. How
>>>> would NTP help me spot a single transit with a 250 ms round trip and
>>>> identify the
>>>> time it occured? Keep in mind that NTP is going to throttle back to a
>> very
>>>> low level
>>>> of “chat” quite quickly…..
>>>> 
>>> 
>>> I don't understand about NTP throttling back? Yes it quickly figure out
>> the
>>> best poll interval to each of the configure reference clocks but that is
>> a
>>> good thing.
>> 
>> Not a good thing if you want to check the link at least once a second and
>> keep
>> doing so for days and days. If the objective is to profile the timing
>> stability of
>> the WiFi link *and* catch all the stupid things that happen … you need a
>> lot
>> of data. There are things that happen at widely spaced intervals. Is a
>> ping the
>> best thing to use? Certainly not. There just aren’t a lot of other
>> candidates.
>> Indeed there can be such a thing as “to much data”, there is an ADEV thread
>> going along about that.
>> 
>> Bob
>> 
>>> You like those poll intervals to be as long as possible
>>> 
>>> It will tell you the TIME an event occurred with good accuracy.  Record
>> the
>>> ping delay and the ping's time of day in the file.  Then if you want to
>>> compare files between different logs made on different computers you can
>>> know that all the time stamps are comparable.  I assume you want to know
>>> the cause so you'd have to look at logs from other devices on your
>> network
>>> 
>>> Question: do something happen every hour to cause this or is that
>> something
>>> happening say every 13 seconds and sets in phase with the ping interval
>>> every hour?
>>> 
>>> Audio over wifi depends on "buffering".  The data are sent in packets or
>>> batches.  The device that actually plays the audio will keep as much as a
>>> few seconds of data and request more when the buffer gets about 1/2
>> empty.
>>> So delays over wifi are not important.   The re-timing is done on the
>>> receiving end, likely using a cheap crystal.
>>> 
>>> Audio over USB, HDMI to fiber TOSLINK is packetized as well and buffered
>>> and re-clocked at the receiving end.  The difference is the size of the
>>> buffer.  If it is packetized then it must be buffered and rechecked, no
>> way
>>> out of that.
>>> 
>>> So yes it is "giant buffers".  The data sent does contain the format, how
>>> many channels, the sample rate and so forth
>> 
>> … but If you are playing the sound out of multiple speakers scattered
>> around the
>> room *and* their only link is WiFi, time sync does matter. That’s what
>> started this
>> thread in the first place. Milisecond sync isn’t good enough in this cas

Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi


Again, this is why the interest in “how the heck did they accomplish it?
With the claim of microsecond level performance, they must have run
into all these issues. 



Just a note: any time I want to do anything that matters, I put it on 5 GHz.
There are still issues, but not quite as many. The data I presented is 
from a 5 GHz link. There’s also data over the same time period showing
LAN pings all running below 1 ms for the same 24 hour period. The random
delay bumps are WiFi specific. 

Bob

> On Jan 15, 2017, at 12:51 AM, Bill Hawkins  wrote:
> 
> 
> I haven't read the entire thread, but this may be relevant. If not, you
> know where to find the delete key.
> 
> I live in a life care community - one of 450 people in 300 apartments on
> 3 floors. When I moved in a year ago, I could get Internet from the
> house cable, and they provided the modem. I bought wired and wireless
> 802.11n dual band routers for two apartments, a two bedroom for us and
> an alcove for my shop. There was plenty of noise from other such
> routers, but no problem within an apartment. I couldn't use a wireless
> keyboard, though. The cursor wandered around with the noise.
> 
> Last month, a company experienced in wiring hotels for wireless put DSL
> to RJ-45 and 11n wireless access points in each apartment on the second
> floor, adding 100 transmitters to the mix. DSL with existing phone
> wiring was far cheaper than running new cable. The intent was to provide
> universal public Wi-Fi for the children of the residents.
> 
> They might as well have installed 100 jammers. There were complaints of
> unusable cordless phones (most in the 2.4 GHz range) and lost Wi-Fi
> connections that simply reverted to the default IP address range and
> failed to reconnect.
> 
> I got a home copy (this is my home) of InSSIDer software and surveyed
> the halls at 2.4 GHz with a Windows 7 laptop (you need a larger screen
> to see the signal distribution) I could see 10 to 20 of the new access
> points, as well as the occasional excursion to -10 dbm (top of scale) as
> nearby routers and printers kicked in. Great stuff.
> 
> There are environments where time sync with Wi-Fi hasn't got a chance.
> 
> Jim Lux was looking for a COTS solution to time sync, and this might
> work in a controlled environment.
> 
> Don't even think about consumer radio clocks that sync from unknown
> Wi-Fi environments.
> 
> Bill Hawkins (John Hawkins son)
> bill.i...@pobox.com
> 
> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

Maybe the magic stamping has been hiding in the chips all along. 
What’s pretty clear is that if it’s there, it’s well hidden ….

Bob

> On Jan 14, 2017, at 7:04 PM, jimlux  wrote:
> 
> On 1/14/17 3:32 PM, Bob Camp wrote:
>> Hi
>> 
>> 
>>> On Jan 14, 2017, at 5:29 PM, Scott Stobbe  wrote:
>>> 
>>> I don't think wifi is ever going to be a real-time system, as it shares the
>>> ether with all other ISM devices. That said even 1 ms of variation is still
>>> 4 orders of magnitude greater than the actual time of flight.
>>> 
>>> The precision time aspect will most certainly be done in hardware, even if
>>> it's just as simple as a timestamp of receiving the beacon frame.
>> 
>> My concern *is* that it’s going to be like 1588 in that respect. Off we all 
>> have
>> to buy new time stamping hardware. Until that’s all up and running
>> you don’t get the new timing stuff. Based on what I see, there’s not a lot
>> of hope for it otherwise.
>> 
> 
> 
> just rummmaging through some datasheets..
> I see that for the SG922-0007 (a WiFi module with AT command set) they do 
> list a value that can be read for "timestamp of last received packet" and 
> "timestamp of last transmitted packet"
> 
> 
> As to what those might mean??
> 
> A Copperhead WiFi shield for Arduino has a microchip MRF24WB0MA on it (it's a 
> few years old, I think it's been replaced by something newer)
> 
> Microchip doesn't make it easy to find the SPI interface details, though.
> 
> 
> 
> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi


> On Jan 14, 2017, at 5:29 PM, Scott Stobbe  wrote:
> 
> I don't think wifi is ever going to be a real-time system, as it shares the
> ether with all other ISM devices. That said even 1 ms of variation is still
> 4 orders of magnitude greater than the actual time of flight.
> 
> The precision time aspect will most certainly be done in hardware, even if
> it's just as simple as a timestamp of receiving the beacon frame.

My concern *is* that it’s going to be like 1588 in that respect. Off we all 
have 
to buy new time stamping hardware. Until that’s all up and running 
you don’t get the new timing stuff. Based on what I see, there’s not a lot
of hope for it otherwise. 

Bob

> 
> On Sat, Jan 14, 2017 at 3:35 PM, Bob Camp  wrote:
> 
>> Hi

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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

Here’s what I am seeing:

64 bytes from 192.168.2.2: icmp_seq=3700 ttl=64 time=5.025 ms
64 bytes from 192.168.2.2: icmp_seq=3701 ttl=64 time=4.579 ms
64 bytes from 192.168.2.2: icmp_seq=3702 ttl=64 time=1.511 ms
64 bytes from 192.168.2.2: icmp_seq=3703 ttl=64 time=1.601 ms
64 bytes from 192.168.2.2: icmp_seq=3704 ttl=64 time=2.370 ms
64 bytes from 192.168.2.2: icmp_seq=3705 ttl=64 time=4.376 ms
64 bytes from 192.168.2.2: icmp_seq=3706 ttl=64 time=2.503 ms
64 bytes from 192.168.2.2: icmp_seq=3707 ttl=64 time=4.923 ms
64 bytes from 192.168.2.2: icmp_seq=3708 ttl=64 time=4.458 ms
64 bytes from 192.168.2.2: icmp_seq=3709 ttl=64 time=33.322 ms
64 bytes from 192.168.2.2: icmp_seq=3710 ttl=64 time=2.006 ms
64 bytes from 192.168.2.2: icmp_seq=3711 ttl=64 time=1.750 ms
64 bytes from 192.168.2.2: icmp_seq=3712 ttl=64 time=122.948 ms
64 bytes from 192.168.2.2: icmp_seq=3713 ttl=64 time=9.869 ms
64 bytes from 192.168.2.2: icmp_seq=3714 ttl=64 time=24.545 ms
64 bytes from 192.168.2.2: icmp_seq=3715 ttl=64 time=1.944 ms
64 bytes from 192.168.2.2: icmp_seq=3716 ttl=64 time=63.656 ms
64 bytes from 192.168.2.2: icmp_seq=3717 ttl=64 time=126.056 ms
64 bytes from 192.168.2.2: icmp_seq=3718 ttl=64 time=99.767 ms
64 bytes from 192.168.2.2: icmp_seq=3719 ttl=64 time=72.922 ms
64 bytes from 192.168.2.2: icmp_seq=3720 ttl=64 time=4.168 ms
64 bytes from 192.168.2.2: icmp_seq=3721 ttl=64 time=3.995 ms
64 bytes from 192.168.2.2: icmp_seq=3722 ttl=64 time=5.065 ms
64 bytes from 192.168.2.2: icmp_seq=3723 ttl=64 time=2.609 ms
64 bytes from 192.168.2.2: icmp_seq=3724 ttl=64 time=4.355 ms
64 bytes from 192.168.2.2: icmp_seq=3725 ttl=64 time=4.979 ms
64 bytes from 192.168.2.2: icmp_seq=3726 ttl=64 time=4.551 ms
64 bytes from 192.168.2.2: icmp_seq=3727 ttl=64 time=1.315 ms
64 bytes from 192.168.2.2: icmp_seq=3728 ttl=64 time=3.747 ms
64 bytes from 192.168.2.2: icmp_seq=3729 ttl=64 time=4.426 ms
64 bytes from 192.168.2.2: icmp_seq=3730 ttl=64 time=4.243 ms
64 bytes from 192.168.2.2: icmp_seq=3731 ttl=64 time=4.202 ms
64 bytes from 192.168.2.2: icmp_seq=3732 ttl=64 time=4.382 ms

Each ping is about one second. 

A 64 second spacing on the round trip “check signals” would likely 
miss this sort of issue. On the other hand, if you are trying to send 
PPS time info *and* see the same sort of “bump” things are likely 
to go tilt pretty quickly. 

The range of the bump can go up to over half a second, but only
does that rarely. Timing between bumps is in the “hours” range.

Is this the nanoseconds or picoseconds that we normally work in?
Certainly not. It *is* something that could really mess up time 
transfer via WiFi if (note the if) it applies to other traffic as well.
There are a lot of people running around trying to move from wired
LAN’s to full WiFi. 

Bob

> On Jan 14, 2017, at 3:08 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> Ok, what I see is that every few hours, I get a “rogue delay” on a single
>> ping. How would NTP help me spot a single transit with a 250 ms round trip
>> and identify the  time it occured? Keep in mind that NTP is going to
>> throttle back to a very low level of “chat” quite quickly….. 
> 
> If you turn on ntpd's rawstats, it will write an entry for each packet 
> exchange with 4 time stamps.  If you assume the clocks on both systems are 
> accurate, you can get the transit times in each direction.  That will tell 
> you which direction is having troubles.  That may or may not be useful 
> information.
> 
> You can make ntpd poll more frequently with maxpoll on the server line.  I 
> think the normal default min is 64 seconds.  You can get more by using more 
> servers.  If that's not fast enough, poke me off list and I'll write a hack 
> that will do it faster and/or write the log files in a format you like.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi


> On Jan 14, 2017, at 1:38 PM, Chris Albertson  
> wrote:
> 
> On Sat, Jan 14, 2017 at 7:46 AM, Bob Camp  wrote:
> 
>> Hi
>> 
>> Ok, what I see is that every few hours, I get a “rogue delay” on a single
>> ping. How
>> would NTP help me spot a single transit with a 250 ms round trip and
>> identify the
>> time it occured? Keep in mind that NTP is going to throttle back to a very
>> low level
>> of “chat” quite quickly…..
>> 
> 
> I don't understand about NTP throttling back? Yes it quickly figure out the
> best poll interval to each of the configure reference clocks but that is a
> good thing.  

Not a good thing if you want to check the link at least once a second and keep 
doing so for days and days. If the objective is to profile the timing stability 
of 
the WiFi link *and* catch all the stupid things that happen … you need a lot
of data. There are things that happen at widely spaced intervals. Is a ping the 
best thing to use? Certainly not. There just aren’t a lot of other candidates. 
Indeed there can be such a thing as “to much data”, there is an ADEV thread
going along about that. 

Bob

> You like those poll intervals to be as long as possible
> 
> It will tell you the TIME an event occurred with good accuracy.  Record the
> ping delay and the ping's time of day in the file.  Then if you want to
> compare files between different logs made on different computers you can
> know that all the time stamps are comparable.  I assume you want to know
> the cause so you'd have to look at logs from other devices on your network
> 
> Question: do something happen every hour to cause this or is that something
> happening say every 13 seconds and sets in phase with the ping interval
> every hour?
> 
> Audio over wifi depends on "buffering".  The data are sent in packets or
> batches.  The device that actually plays the audio will keep as much as a
> few seconds of data and request more when the buffer gets about 1/2 empty.
>  So delays over wifi are not important.   The re-timing is done on the
> receiving end, likely using a cheap crystal.
> 
> Audio over USB, HDMI to fiber TOSLINK is packetized as well and buffered
> and re-clocked at the receiving end.  The difference is the size of the
> buffer.  If it is packetized then it must be buffered and rechecked, no way
> out of that.
> 
> So yes it is "giant buffers".  The data sent does contain the format, how
> many channels, the sample rate and so forth

… but If you are playing the sound out of multiple speakers scattered around 
the 
room *and* their only link is WiFi, time sync does matter. That’s what started 
this
thread in the first place. Milisecond sync isn’t good enough in this case. You 
need
microsecond level sync. 

Bob

> 
>> 
>> While this *is* getting far more into my WiFi (which I had no real
>> intention of doing) it
>> does apply to timing and running audio over WiFi as well. The basic
>> transport as it
>> runs up through the various layers is *not* very good time wise. There is
>> indeed a
>> real need for some sort of overlay to take care of that issue. I’d still
>> love to know if
>> this magic protocol is simply giant buffers and some sort of tagging or if
>> they do
>> something more interesting.
>> 
>> Bob
>>> On Jan 14, 2017, at 12:32 AM, Chris Albertson 
>> wrote:
>>> 
>>> On Fri, Jan 13, 2017 at 1:11 PM, Bob Camp  wrote:

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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

The issue with using Wireshark is that it still is looking at a ping. It may 
tag the
event to one more digit, but all of the earlier mentioned issues with pings are
still there. Simply put, they aren’t the greatest thing for testing timing. 

Bob

> On Jan 14, 2017, at 1:51 PM, Orin Eman  wrote:
> 
> You could run a network monitor, Wireshark for example...
> 
> https://wiki.wireshark.org/CaptureSetup/WLAN
> 
> There are specialized WIFI capture programs, but they tend to be designed
> to break into networks rather than monitor performance - kismet/kismac.  I
> run them every so often to check for malfeasance in the neighborhood.  The
> Netstumbler kind of apps just try to discover local networks and report
> their signal strengths.
> 
> I'd say Wireshark is a fair bet for packet timing, but even it might not
> have the accuracy desired.  Here is a ping and its response on my WIFI
> network, taken by Wireshark on a late 2012 Mac Mini on its builtin WIFI
> adapter.  It's reporting to micro-second resolution and the ping time is
> around 1.2 ms on this network.  It ranged from 0.993 to 5.927 (first ping)
> over the dozen or so pings before I stopped it.  I don't know where the
> time stamps are taken - whether it's in the OS or when it gets to Wireshark
> itself.  FWIW, the WIFI access point is a Frontier Fios router.
> 
> Frame 955: 98 bytes on wire (784 bits), 98 bytes captured (784 bits) on
> interface 0
>Interface id: 0 (en1)
>Encapsulation type: Ethernet (1)
>Arrival Time: Jan 14, 2017 10:23:01.707462000 PST
>[Time shift for this packet: 0.0 seconds]
>Epoch Time: 1484418181.707462000 seconds
>[Time delta from previous captured frame: 0.501617000 seconds]
>[Time delta from previous displayed frame: 0.501617000 seconds]
>[Time since reference or first frame: 144.374849000 seconds]
>Frame Number: 955
>Frame Length: 98 bytes (784 bits)
>Capture Length: 98 bytes (784 bits)
>[Frame is marked: False]
>[Frame is ignored: False]
>[Protocols in frame: eth:ethertype:ip:icmp:data]
>[Coloring Rule Name: ICMP]
>[Coloring Rule String: icmp || icmpv6]
> Ethernet II, Src: Apple_a2:57:7b (a8:8e:24:a2:57:7b), Dst:
> Actionte_1a:57:9e (00:26:b8:1a:57:9e)
> Internet Protocol Version 4, Src: 192.168.1.10, Dst: 192.168.1.1
> Internet Control Message Protocol
> 
> 
> Frame 956: 98 bytes on wire (784 bits), 98 bytes captured (784 bits) on
> interface 0
>Interface id: 0 (en1)
>Encapsulation type: Ethernet (1)
>Arrival Time: Jan 14, 2017 10:23:01.708586000 PST
>[Time shift for this packet: 0.0 seconds]
>Epoch Time: 1484418181.708586000 seconds
>[Time delta from previous captured frame: 0.001124000 seconds]
>[Time delta from previous displayed frame: 0.001124000 seconds]
>[Time since reference or first frame: 144.375973000 seconds]
>Frame Number: 956
>Frame Length: 98 bytes (784 bits)
>Capture Length: 98 bytes (784 bits)
>[Frame is marked: True]
>[Frame is ignored: False]
>[Protocols in frame: eth:ethertype:ip:icmp:data]
>[Coloring Rule Name: ICMP]
>[Coloring Rule String: icmp || icmpv6]
> Ethernet II, Src: Actionte_1a:57:9e (00:26:b8:1a:57:9e), Dst:
> Apple_a2:57:7b (a8:8e:24:a2:57:7b)
> Internet Protocol Version 4, Src: 192.168.1.1, Dst: 192.168.1.10
> Internet Control Message Protocol
> 
> 
> On Sat, Jan 14, 2017 at 9:44 AM, jimlux  wrote:
> 
>> On 1/14/17 8:35 AM, Bob Camp wrote:
>> 
>>> Hi
>>> 
>>> 
>> 
>>> I also believe that ping data is one way to come up with an upper bound on
>>> just how awful WiFi timing can be.  If others have a similar single shot
>>> measure
>>> of WiFi round trip that can be run on a wide range of devices, I’d
>>> certainly be just
>>> as interested in that.
>>> 
>>> 
>> does software like netstumbler and such have lower level diagnostic
>> measurements?
>> 
>> There's a variety of apps for my phones that provide some info on WiFi
>> networks, but I think it's all sort of in the "received signal strength"
>> kind of level.  I've not seen anything for timing.  But that's not to say
>> that it doesn't exist.
>> 
>> I seem to recall some folks fooling with various timing parameters that
>> can be set into 802.11 chipsets from 10 years ago.  Today's interfaces? I
>> don't know.  The little interfaces that you put on a Arduino and such
>> expose a serial port kind of interface with a AT command set.  I think they
>> bury most all of the stuff we'd want to know about.
>> 
>> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

> On Jan 14, 2017, at 12:44 PM, jimlux  wrote:
> 
> On 1/14/17 8:35 AM, Bob Camp wrote:
>> Hi
>> 
> 
>> 
>> I also believe that ping data is one way to come up with an upper bound on
>> just how awful WiFi timing can be.  If others have a similar single shot 
>> measure
>> of WiFi round trip that can be run on a wide range of devices, I’d certainly 
>> be just
>> as interested in that.
>> 
> 
> does software like netstumbler and such have lower level diagnostic 
> measurements?
> 
> There's a variety of apps for my phones that provide some info on WiFi 
> networks, but I think it's all sort of in the "received signal strength" kind 
> of level.  I've not seen anything for timing.  But that's not to say that it 
> doesn't exist.

Before this all headed off into the weeds, it *was* a topic looking for more 
info on WiFi based timing enhancements. We still do not seem to have any real 
input on that side of it. 
Hopefully somebody will pipe in at some point with real info on what the WiFI 
chipset guys are trying to do. At some point I would think it’s got to be made 
public ….

Bob

> 
> I seem to recall some folks fooling with various timing parameters that can 
> be set into 802.11 chipsets from 10 years ago.  Today's interfaces? I don't 
> know.  The little interfaces that you put on a Arduino and such expose a 
> serial port kind of interface with a AT command set.  I think they bury most 
> all of the stuff we'd want to know about.
> 
> 
> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

We have a double issue here:

1) It’s a problem because “not enough information was given"

2) It’s a problem because “we are talking about it to much”

Sorry, but there is absolutely no way at all both of those criteria can
be met by me.  

I do believe that WiFi time protocols are an on topic item for TimeNuts. 
Given our ability to wander off topic for weeks on some subjects, it is
a bit unclear just where those bounds actually are. 

I also believe that ping data is one way to come up with an upper bound on 
just how awful WiFi timing can be.  If others have a similar single shot 
measure 
of WiFi round trip that can be run on a wide range of devices, I’d certainly be 
just 
as interested in that. 

Bob

> On Jan 14, 2017, at 10:53 AM, John Hawkinson  wrote:
> 
> This has nothing to do with time-nuts, can it stop please?
> 
> [ I don't know what forum to send you to for "weird wifi problems"; there
> is probably no good one, because it is a very common consumer problem :( ]
> 
> NTP was mentioned because you (Bob Camp) had not defined the problem
> very well, and asked some questions that it can solve. It will not


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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

This is very much a one laptop to one router issue. The other couple dozen 
laptops
and tablets do not see an issue. The whole thing started when a series of 
firmware 
updates rolled through a few weeks ago. The laptop is *maybe* 12 feet from the 
router.
It’s running at 5 GHz so microwaves (and a lot of other stuff) are not an 
issue. 

Bob

> On Jan 14, 2017, at 1:15 AM, Chuck Harris  wrote:
> 
> If there is a modern microwave oven with a switching power supply,
> or a cordless telephone around, you might want to look there.
> 
> The old linear supply ovens were easy to deal with because they
> presented a strong CW signal that drifted around as voltage, load,
> and temperature changed.  The switcher ovens simply splatter the
> whole ISM band with strong microwave noise.
> 
> -Chuck Harris
> 
> Bob Camp wrote:
>> Hi
>> 
>> It just so happens that I’m trying to track down an issue with my WiFi as
>> I type this. My *guess* is that there is a dropout going on. The only easy
>> way I can see to get a round trip time with a high data rate is to run ping. 
>> It’s the only tool that gives me something that is fast enough to spot 
>> issues.
>> Is it perfect? certainly not. Is it an upper bound that is also likely the 
>> limit
>> for things like NTP - in my experience it sure is. That of course assumes 
>> the gizmo that sends the pings back does so quickly and consistently. I’ve
>> spent enough time testing that side of it that I’m quite sure it’s true in 
>> this case.
>> 
>> Bob
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

Ok, what I see is that every few hours, I get a “rogue delay” on a single ping. 
How
would NTP help me spot a single transit with a 250 ms round trip and identify 
the 
time it occured? Keep in mind that NTP is going to throttle back to a very low 
level
of “chat” quite quickly…..

While this *is* getting far more into my WiFi (which I had no real intention of 
doing) it
does apply to timing and running audio over WiFi as well. The basic transport 
as it
runs up through the various layers is *not* very good time wise. There is 
indeed a 
real need for some sort of overlay to take care of that issue. I’d still love 
to know if 
this magic protocol is simply giant buffers and some sort of tagging or if they 
do
something more interesting. 

Bob
> On Jan 14, 2017, at 12:32 AM, Chris Albertson  
> wrote:
> 
> On Fri, Jan 13, 2017 at 1:11 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> Ok. so I bring up NTP on the laptop against a server on the other side of
>> the country and install
>> NTP on the laptop. I get all of the jitter and offset of my cable modem
>> plus the network
>> issues between here and who know where. If I want to know the specific
>> delay issues just
>> on the WiFi connection (like when it rotates keys), how do I separate that
>> out?
>> 
> 
> Run an NTP server on your local network with a wired connection to the
> router.Also in many cases the router itself can run NTP.
> 
> If you are looking for smaller delays than NTP's level of uncertainty which
> is going to be some tens of milliseconds then you need a hardware back
> channel.  What I would do in that case is get s GPS with one pulse per
> second output and feed that to BOTH the laptop and the wired NTP server.
> Both servers will eventually sync to the 1PPS and have clocks running at
> some tens of microseconds from each other.   With clocks on both computers
> sync's to that level you can trust time stamped log files.  But this
> requires a source of the 1PPS and some custom cables.   If tens of
> milliseconds is OK (that is 1,000 times worse) then software and one
> Ethernet cable are enough
> 
> In short the best way is to have all the internal clocks of the computers
> running UTC to some very close tolerance then when something happens you
> log it and later process logs
> 
> Another idea;   Connect the laptop to an NTP server with 100BaseT cable and
> set up NTP to look ONLY over that interface.  Then bring up wifi for all
> other uses.   The time sync will be maintained at millisecond level over
> Ethernet then do your WiFi experiments.   The 1PPS a couple orders of
> magnitude better but more work too.
> 
> Actually your initial comment is right, you be measuring the uncertainty in
> the WiFi delay added to the uncertainty in the Internet connection.  But he
> local WiFi would be 10x worse (at least) and dominate.  If you used 5 or 7
> NTP servers then NTP can figure out the uncertainty over the Internet by
> comparing a large number of them and the effects of the local WiFi  account
> for most of it.
> 
> All that said, you can buy a good enough GPS receiver on eBay for about $10
> now.   One trouble is getting that 1PPS signal into a laptop that lacks a
> serial port.  Using a USB dongle serieould degrades the timing accuracy.
> But still the BEST way to distribute time sync is via a hardware 1PPS
> network.  I use old RG58 coax salvaged from an old Ethernet to distribute
> 1PPS.The source of error is in the nanosecond range and mostly comes
> from speed of light delays in the wire and not measuring the wire correctly
> or not accounting for velocity factor correctly or noise.   But even so NTP
> using a 1PPS  reference clock is going to keep the computer's system clock
> accurate at close to the level off the system clock's resolution
> 
> 
>> 
>> Bob
>> 
>>> On Jan 13, 2017, at 3:45 PM, Chris Albertson 
>> wrote:
>>> 
>>> Short answer:  See man page for ntpq
>>> 
>>> Longer...
>>> 
>>> First run NTP then after some time (15 minute to an hour) at the command
>>> line time type "ntpq -p"
>>> 
>>> "ntpq" will query NTP for timing statistics.  It will report the average
>>> delay between the local computer and the set of reference clocks (other
>>> servers) that NTP is connected to.  Along with the average delay you get
>>> variation in that delay (std dev?)Note the if NTP can calculate the
>>> delay, it has already compensated for it.   It is only the uncertainty of
>>> the compensation that matters, hence the need to report the variation.
>>> 
>>> The data shows the total delay and vari

Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

It just so happens that I’m trying to track down an issue with my WiFi as
I type this. My *guess* is that there is a dropout going on. The only easy
way I can see to get a round trip time with a high data rate is to run ping. 
It’s the only tool that gives me something that is fast enough to spot issues.
Is it perfect? certainly not. Is it an upper bound that is also likely the limit
for things like NTP - in my experience it sure is. That of course assumes 
the gizmo that sends the pings back does so quickly and consistently. I’ve
spent enough time testing that side of it that I’m quite sure it’s true in this 
case.

Bob

> On Jan 13, 2017, at 4:07 PM, John Hawkinson  wrote:
> 
> Bob Camp  wrote on Fri, 13 Jan 2017
> at 15:35:19 -0500 in :
> 
>> What standard protocol would you recommend I run from the command
>> line on my computer to get a quick estimate of the timing lag and
>> variablilty on my particular WiFi connection?
> 
> Bob: I hope you read the whole of my message, rather than just the
> short upper part you quoted. I said "I'm not aware of a tool that does
> this today" -- I don't think there is a good answer.
> 
> 
> ==> There isn't one. <==
> 
> 
> You can certainly use ping to get a gross upper bound. But rememnber
> it's a gross upper bound, and the underlying technology can do much
> better. As Chris said, ntp will do a good job telling you the delay
> between two hosts (that are running ntp and talking to each other)
> by sending a lot of samples and averaging over time.
> 
> But what is your application here? You haven't made it clear.  Ping is
> not representative of what you could get with a wifi using a new
> technology, which was what was how this thread started, and so the
> context some of the anwers (esp. mine) are in. Ping is representative
> of other things, though.
> 
> --jh...@mit.edu
>  John Hawkinson
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

Ok. so I bring up NTP on the laptop against a server on the other side of the 
country and install
NTP on the laptop. I get all of the jitter and offset of my cable modem plus 
the network
issues between here and who know where. If I want to know the specific delay 
issues just 
on the WiFi connection (like when it rotates keys), how do I separate that out?

Bob

> On Jan 13, 2017, at 3:45 PM, Chris Albertson  
> wrote:
> 
> Short answer:  See man page for ntpq
> 
> Longer...
> 
> First run NTP then after some time (15 minute to an hour) at the command
> line time type "ntpq -p"
> 
> "ntpq" will query NTP for timing statistics.  It will report the average
> delay between the local computer and the set of reference clocks (other
> servers) that NTP is connected to.  Along with the average delay you get
> variation in that delay (std dev?)Note the if NTP can calculate the
> delay, it has already compensated for it.   It is only the uncertainty of
> the compensation that matters, hence the need to report the variation.
> 
> The data shows the total delay and variation over the network and the
> reference clocks might be thousands of miles away.  So you might want to
> run one on say your wifi router or a local computer with hardwire
> connection to the router then you'd see the effect of only your wifi.
> 
> 
> 
> On Fri, Jan 13, 2017 at 12:35 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> What standard protocol would you recommend I run from the command line on
>> my computer
>> to get a quick estimate of the timing lag and variablilty  on my
>> particular WiFi connection?
>> 
>> Bob
>> 
>>> On Jan 13, 2017, at 3:25 PM, John Hawkinson  wrote:
>>> 
>>> Can we please stop talking about pings?
>>> 
>>> Bob Camp  wrote on Fri, 13 Jan 2017
>>> at 15:12:38 -0500 in :
>>> 
>>>> I’m sure you are right about the response time. Right now the
>>>> variation is running almost 3 ms at one sigma on a ping so there is
>>>> a lot to do simply to get the accuracy anywhere near 1 us.
>>> 
>> 
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>> and follow the instructions there.
>> 
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

That *assumes* that NTP is installed on the laptop.

Bob

> On Jan 13, 2017, at 3:45 PM, Chris Albertson  
> wrote:
> 
> Short answer:  See man page for ntpq
> 
> Longer...
> 
> First run NTP then after some time (15 minute to an hour) at the command
> line time type "ntpq -p"
> 
> "ntpq" will query NTP for timing statistics.  It will report the average
> delay between the local computer and the set of reference clocks (other
> servers) that NTP is connected to.  Along with the average delay you get
> variation in that delay (std dev?)Note the if NTP can calculate the
> delay, it has already compensated for it.   It is only the uncertainty of
> the compensation that matters, hence the need to report the variation.
> 
> The data shows the total delay and variation over the network and the
> reference clocks might be thousands of miles away.  So you might want to
> run one on say your wifi router or a local computer with hardwire
> connection to the router then you'd see the effect of only your wifi.
> 
> 
> 
> On Fri, Jan 13, 2017 at 12:35 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> What standard protocol would you recommend I run from the command line on
>> my computer
>> to get a quick estimate of the timing lag and variablilty  on my
>> particular WiFi connection?
>> 
>> Bob
>> 
>>> On Jan 13, 2017, at 3:25 PM, John Hawkinson  wrote:
>>> 
>>> Can we please stop talking about pings?
>>> 
>>> Bob Camp  wrote on Fri, 13 Jan 2017
>>> at 15:12:38 -0500 in :
>>> 
>>>> I’m sure you are right about the response time. Right now the
>>>> variation is running almost 3 ms at one sigma on a ping so there is
>>>> a lot to do simply to get the accuracy anywhere near 1 us.
>>> 
>> 
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>> and follow the instructions there.
>> 
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

What standard protocol would you recommend I run from the command line on my 
computer 
to get a quick estimate of the timing lag and variablilty  on my particular 
WiFi connection?

Bob

> On Jan 13, 2017, at 3:25 PM, John Hawkinson  wrote:
> 
> Can we please stop talking about pings?
> 
> Bob Camp  wrote on Fri, 13 Jan 2017
> at 15:12:38 -0500 in :
> 
>> I’m sure you are right about the response time. Right now the
>> variation is running almost 3 ms at one sigma on a ping so there is
>> a lot to do simply to get the accuracy anywhere near 1 us.
> 

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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

I’m sure you are right about the response time. Right now the variation is 
running almost 3 ms
at one sigma on a ping so there is a lot to do simply to get the accuracy 
anywhere near 1 us.

Bob

> On Jan 13, 2017, at 2:35 PM, Chris Caudle  wrote:
> 
> On Fri, January 13, 2017 11:40 am, Bob Camp wrote:
>> The ping response is anywhere from 2 ms out to 400 ms. Most of
>> the time it's in the 3 to 9 ms range. Simply taking that
>> down to < 1 us would be a really big deal.
> 
> I doubt that the response time will get that low, rather the time sync
> will be moved lower in the hardware stack so that the variation stays
> below 1us so it can be compensated as a systematic offset.  Basically a
> Wi-Fi version of the hardware time stamping that a lot of NIC's do now for
> PTP support.  Just a guess at this point.
> 
> -- 
> Chris Caudle
> 
> 
> 
> 
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Re: [time-nuts] Thermal effects on cables --> ADEV

[Bob Camp]

Hi


That’s the way I read what they are saying. More or less: Keep the number of 
samples above
100, but below 300.

Bob

> On Jan 13, 2017, at 12:30 PM, Ole Petter Rønningen  
> wrote:
> 
> That IS interesting.. It reads to me that the advice is to keep a "moving 300 
> pt ADEV" when continously monitoring a (pair of) frequency source in e.g a 
> VLBI site - the reason for limiting it to 300 pts being that much more than 
> that is likely to average out potential issues.. 
> 
> Does that make sense?
> 
>> Den 13. jan. 2017 kl. 17.04 skrev Bob Camp :
>> 
>> Hi
>> 
>> There’s an interesting comment buried down in that paper about limiting ADEV 
>> to 
>> < 300 samples per point. Their objective is apparently to better highlight 
>> “systematic 
>> errors”. I certainly agree that big datasets will swamp this sort of thing. 
>> I’m not quite
>> sure that I’d recommend ADEV to find these things in the first place. My 
>> guess is that
>> it’s the only spec they have to call the device good or bad in this case 
>> …They don’t seem
>> to have Hadamard in their list of variances. If I was going after 
>> systematics with a deviation,
>> that’s the one I’d use. Of course I probably would not use a something-dev 
>> in the first place. 
>> 
>> Bob
>> 
>> 
>>> On Jan 13, 2017, at 1:52 AM, Ole Petter Ronningen  
>>> wrote:
>>> 
>>> Hi, all
>>> 
>>> The question of phase shifts in cables pops up every now and then on this
>>> list - I stumbled across a good table of measured phase shifts with
>>> temperature in different cable types in this paper:
>>> http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_PresentationWSchaefer.pdf
>>> that I though would be of interest to others.
>>> 
>>> A quick summary given below, see pdf for full details. Lots of other
>>> interesting stuff in there also.
>>> 
>>> Values in ppm/K, for 10 Mhz except when otherwise stated. (The paper gives
>>> values for 5, 10 and 100Mhz)
>>> 
>>> Huber-Suhner Multiflex 141: -6
>>> RG-223: -131.9
>>> Semiflex Cable: -11.5
>>> Huber-Suhner: -8.6
>>> Times Microwave LMR-240: -3.4
>>> Times Microwave SFT-205: 7.7
>>> Meggitt 2T693 SiO2: 30.6
>>> Andrew FSJ-1 (@5Mhz): 25
>>> Andrew FSJ-4 (@5Mhz): 10
>>> Andrew LDF-1P-50-42: 2.8
>>> Andrew LDF4-50A: 4.7
>>> Times Microwave TF4FLEX (@100Mhz):6.4
>>> Phasetrack PT210 (@100Mhz): 2
>>> 
>>> Ole
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

I probably should have added that I already know that the switch will do sub 1 
ms
LAN pings all day long with the near zero load that it’s running. Sorry about 
that.

Now, there certainly are OS level things on my laptop that will muck up pings. 
Unfortunately 
they also get into a number of timing things as well.

Bob

> On Jan 13, 2017, at 1:08 PM, Denny Page  wrote:
> 
>> On Jan 13, 2017, at 09:40, Bob Camp  wrote:
>> 
>> Just for reference, I happen to be running a ping over my local WiFi to one 
>> of the switches
>> on the LAN. The ping response is anywhere from 2 ms out to 400 ms. Most of 
>> the time it’s 
>> in the 3 to 9 ms range. Simply taking that down to < 1 us would be a really 
>> big deal. 
> 
> 
> Ping, particularly to a switch, is not a good indication of actual latency in 
> a local network. Hosts do not prioritize responding to icmp, and on a switch 
> to icmp is the lowest “I’ll get around to it” priority the switch has. 
> Pinging the switch that my host is directly attached to gives an average of 
> 1.22ms. Pinging another host attached to the same switch gives an average of 
> 100us. The actual port to port latency on the switch is 2.45us. Your mileage 
> may vary.
> 
> Denny
> 
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Re: [time-nuts] Thermal effects on cables --> ADEV

[Bob Camp]

Hi

I do agree with their point that systematics will get buried in giant data 
blocks. 
What I’m not quite as sure of is the utility of even 300 sample blocks to spot
systematic issues.

Bob

> On Jan 13, 2017, at 1:08 PM, Scott Stobbe  wrote:
> 
> I think you might be overthinking their point, that if you plan to use an
> xDEV as a measure for state of health, don't use years worth of data.
> Otherwise it could be days before the xDEV visually changes.
> 
> On Fri, Jan 13, 2017 at 11:04 AM, Bob Camp  wrote:
> 
>> Hi
>> 
>> There’s an interesting comment buried down in that paper about limiting
>> ADEV to
>> < 300 samples per point. Their objective is apparently to better highlight
>> “systematic
>> errors”. I certainly agree that big datasets will swamp this sort of
>> thing. I’m not quite
>> sure that I’d recommend ADEV to find these things in the first place. My
>> guess is that
>> it’s the only spec they have to call the device good or bad in this case
>> …They don’t seem
>> to have Hadamard in their list of variances. If I was going after
>> systematics with a deviation,
>> that’s the one I’d use. Of course I probably would not use a something-dev
>> in the first place.
>> 
>> Bob
>> 
>> 
>>> On Jan 13, 2017, at 1:52 AM, Ole Petter Ronningen 
>> wrote:
>>> 
>>> Hi, all
>>> 
>>> The question of phase shifts in cables pops up every now and then on this
>>> list - I stumbled across a good table of measured phase shifts with
>>> temperature in different cable types in this paper:
>>> http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_
>> PresentationWSchaefer.pdf
>>> that I though would be of interest to others.
>>> 
>>> A quick summary given below, see pdf for full details. Lots of other
>>> interesting stuff in there also.
>>> 
>>> Values in ppm/K, for 10 Mhz except when otherwise stated. (The paper
>> gives
>>> values for 5, 10 and 100Mhz)
>>> 
>>> Huber-Suhner Multiflex 141: -6
>>> RG-223: -131.9
>>> Semiflex Cable: -11.5
>>> Huber-Suhner: -8.6
>>> Times Microwave LMR-240: -3.4
>>> Times Microwave SFT-205: 7.7
>>> Meggitt 2T693 SiO2: 30.6
>>> Andrew FSJ-1 (@5Mhz): 25
>>> Andrew FSJ-4 (@5Mhz): 10
>>> Andrew LDF-1P-50-42: 2.8
>>> Andrew LDF4-50A: 4.7
>>> Times Microwave TF4FLEX (@100Mhz):6.4
>>> Phasetrack PT210 (@100Mhz): 2
>>> 
>>> Ole
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

Just for reference, I happen to be running a ping over my local WiFi to one of 
the switches
on the LAN. The ping response is anywhere from 2 ms out to 400 ms. Most of the 
time it’s 
in the 3 to 9 ms range. Simply taking that down to < 1 us would be a really big 
deal. 

Bob

> On Jan 13, 2017, at 12:06 PM, walter shawlee 2  wrote:
> 
> they were really short on hard details about this new technology.
> the *WiFi alliance* website only shows this off-site article link I found 
> under NEWS:
> 
> http://www.rcrwireless.com/20170104/test-and-measurement/20170104test-and-measurementwi-fi-alliance-to-certify-timesync-among-multiple-devices-tag6
> 
> the main alliance site is here:
> http://www.wi-fi.org/   but I don't see anything helpful other than this
> general explanation of TimeSync:
> http://www.wi-fi.org/discover-wi-fi/wi-fi-timesync
> 
> but meaty details that might help us are hard to find.
> 
> all the best,
> walter
> 
> 
> Walter Shawlee 2, President
> Sphere Research Corporation
> 3394 Sunnyside Rd.,  West Kelowna,  BC
> V1Z 2V4  CANADA  Phone: (250) 769-1834
> walt...@sphere.bc.ca
> WS2: We're all in one boat, no matter how it looks to you.
> Love is all you need. (John Lennon)
> But, that doesn't mean other things don't come in handy. (WS2)
> 
> On 2017-01-13 08:47 AM, Joshua Pollack wrote:
>> I saw this article too -- is anyone aware of something with more
>> technical details?  For example, where in the protocol stack does it
>> work?  Is it specific to 802.11 or general purpose ethernet?
>> 
>> Speaking as someone who has a primary hobby of the development of
>> super low cost time sync algorithms and software implementations with
>> the express application of audio over disparate clocks...  this
>> interests me.
>> 
>> Joshua
>> 
>> On Fri, Jan 13, 2017 at 08:30:44AM -0800, walter shawlee 2 wrote:
>>> While probably not tight enough for time nuts use, there is a new
>>> WiFi technology shown at CES that provides time sync between nodes
>>> to allow audio to be simulcast over many locations.  the info (in
>>> short form) is here for those interested:
>>> 
>>> http://electronicdesign.com/embedded/upgrade-wi-fi-provides-precise-time-sychronization?NL=ED-001&Issue=ED-001_20170113_ED-001_372&sfvc4enews=42&cl=article_2_b&utm_rid=CPG0502043119&utm_campaign=9246&utm_medium=email&elq2=a803bc263ff84affa98f3ddbd0650ec0
>>> 
>>> there might be some way it can be used for more precision purposes
>>> down the road. I just thought it might be of interest to the group.
>>> all the best,
>>> walter
>>> 
>>> -- 
>>> Walter Shawlee 2, President
>>> Sphere Research Corporation
>>> 3394 Sunnyside Rd.,  West Kelowna,  BC
>>> V1Z 2V4  CANADA  Phone: (250) 769-1834
>>> walt...@sphere.bc.ca
>>> WS2: We're all in one boat, no matter how it looks to you.
>>> Love is all you need. (John Lennon)
>>> But, that doesn't mean other things don't come in handy. (WS2)
>>> 
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Re: [time-nuts] wifi with time sync

[Bob Camp]

Hi

A lot depends on how much “less than a microsecond” the chip sets really 
deliver in the real world. If they get down into
the sub 100 ns range (which they might), it’s a very useful thing for relaying 
GPS data from a roof antenna down to an 
NTP server in the basement. 1588 is a “less than a microsecond” sort of 
approach that does indeed get down to nanosecond
sort of levels. This could be similar. 

Bob

> On Jan 13, 2017, at 11:30 AM, walter shawlee 2  wrote:
> 
> While probably not tight enough for time nuts use, there is a new WiFi 
> technology shown at CES that provides time sync between nodes to allow audio 
> to be simulcast over many locations.  the info (in short form) is here for 
> those interested:
> 
> http://electronicdesign.com/embedded/upgrade-wi-fi-provides-precise-time-sychronization?NL=ED-001&Issue=ED-001_20170113_ED-001_372&sfvc4enews=42&cl=article_2_b&utm_rid=CPG0502043119&utm_campaign=9246&utm_medium=email&elq2=a803bc263ff84affa98f3ddbd0650ec0
> 
> there might be some way it can be used for more precision purposes down the 
> road. I just thought it might be of interest to the group.
> all the best,
> walter
> 
> -- 
> Walter Shawlee 2, President
> Sphere Research Corporation
> 3394 Sunnyside Rd.,  West Kelowna,  BC
> V1Z 2V4  CANADA  Phone: (250) 769-1834
> walt...@sphere.bc.ca
> WS2: We're all in one boat, no matter how it looks to you.
> Love is all you need. (John Lennon)
> But, that doesn't mean other things don't come in handy. (WS2)
> 
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Re: [time-nuts] Thermal effects on cables --> ADEV

[Bob Camp]

Hi

There’s an interesting comment buried down in that paper about limiting ADEV to 
< 300 samples per point. Their objective is apparently to better highlight 
“systematic 
errors”. I certainly agree that big datasets will swamp this sort of thing. I’m 
not quite
sure that I’d recommend ADEV to find these things in the first place. My guess 
is that
it’s the only spec they have to call the device good or bad in this case …They 
don’t seem
to have Hadamard in their list of variances. If I was going after systematics 
with a deviation,
that’s the one I’d use. Of course I probably would not use a something-dev in 
the first place. 

Bob


> On Jan 13, 2017, at 1:52 AM, Ole Petter Ronningen  
> wrote:
> 
> Hi, all
> 
> The question of phase shifts in cables pops up every now and then on this
> list - I stumbled across a good table of measured phase shifts with
> temperature in different cable types in this paper:
> http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_PresentationWSchaefer.pdf
> that I though would be of interest to others.
> 
> A quick summary given below, see pdf for full details. Lots of other
> interesting stuff in there also.
> 
> Values in ppm/K, for 10 Mhz except when otherwise stated. (The paper gives
> values for 5, 10 and 100Mhz)
> 
> Huber-Suhner Multiflex 141: -6
> RG-223: -131.9
> Semiflex Cable: -11.5
> Huber-Suhner: -8.6
> Times Microwave LMR-240: -3.4
> Times Microwave SFT-205: 7.7
> Meggitt 2T693 SiO2: 30.6
> Andrew FSJ-1 (@5Mhz): 25
> Andrew FSJ-4 (@5Mhz): 10
> Andrew LDF-1P-50-42: 2.8
> Andrew LDF4-50A: 4.7
> Times Microwave TF4FLEX (@100Mhz):6.4
> Phasetrack PT210 (@100Mhz): 2
> 
> Ole
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Re: [time-nuts] General questions about making measurements with time interval counter.

[Bob Camp]

Hi


> On Jan 12, 2017, at 4:06 PM, Bob Stewart  wrote:
> 
> Hi Bob,
> OK, like Bugs Bunny, I'll venture out on the limb, cut the limb, and see 
> whether I fall or the tree falls:
> Wouldn't it take 1801 samples to get 18 seconds at 100S tau?  Maybe I didn't 
> state that properly, but I think you get my meaning.  Also, I've never 
> actually taken the time to look at the formula or the code to see how the 
> ADEV is calculated.  But doesn't it use a sliding boxcar type of calculation? 
>  

Nope, the proper approach for ADEV is to decimate the sample set.

Bob

> Or is that some other *DEV?  My point is that for 1801 seconds, aren't there 
> a lot more than 18 samples put in the 100S bin?  And I've probably stated 
> that incorrectly, too.  
> 
> Bob
> 
> 
>  From: Bob Camp 
> To: Bob Stewart ; Discussion of precise time and frequency 
> measurement  
> Sent: Thursday, January 12, 2017 2:38 PM
> Subject: Re: [time-nuts] General questions about making measurements with 
> time interval counter.
> 
> Hi
> 
> Keep in mind that when you do 1800 samples at 1 second, that data will only 
> meet the 
> 100 sample requirement out to tau = 18 seconds. Past that you are in the 
> “under 100 samples
> region”.
> 
> Bob
> 
>> On Jan 12, 2017, at 2:32 PM, Bob Stewart  wrote:
>> 
>> Hi Bob,
>> OK, thanks for explaining.  When you and others use highly technical terms 
>> like "small number of samples" it's not always clear to me what you mean.  
>> =)  Ten samples?  That's not enough for anything.  Normally I run at least 
>> 1800 samples; at least if I plan to share them with someone.
>> 
>> Bob -
>> AE6RV.com
>> 
>> GFS GPSDO list:
>> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>> 
>>   From: Bob Camp 
>> To: Bob Stewart ; Discussion of precise time and frequency 
>> measurement  
>> Sent: Thursday, January 12, 2017 1:03 PM
>> Subject: Re: [time-nuts] General questions about making measurements with 
>> time interval counter.
>> 
>> Hi
>> 
>> It varies from 5370 to 5370. You see a lot of plots that run out to 10 
>> samples or less. Anything below 100 samples
>> is risky in some senses.
>> 
>> Bob
>> 
>>> On Jan 12, 2017, at 12:25 PM, Bob Stewart  wrote:
>>> 
>>> Hi Bob,
>>> OK, what's a small number of data points?  Attached is a screencap of 
>>> captures for 25, 50, 75, 100, and 150 seconds.  Yeah, at 25 seconds, the 1S 
>>> tau is up at 4.56E-11, but it falls pretty quickly.  I will mention that 
>>> this particular 5370 is much better than my other one.  So, maybe this one 
>>> is an exceptional example?
>>> 
>>> Just for grins, I also included a screencap of the phase points.
>>> 
>>> Bob -
>>> AE6RV.com
>>> 
>>> GFS GPSDO list:
>>> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>>> 
>>>   From: Bob Camp 
>>> To: Bob Stewart ; Discussion of precise time and frequency 
>>> measurement  
>>> Sent: Thursday, January 12, 2017 11:04 AM
>>> Subject: Re: [time-nuts] General questions about making measurements with 
>>> time interval counter.
>>> 
>>> Hi
>>> 
>>> There is a big difference between RMS and single shot. Single shot, the 
>>> 5370 is a very different beast. 
>>> That’s not a big deal when you have a few thousand readings and it all 
>>> averages down. Unfortunately 
>>> we all love to do runs with a very small number of points and then draw 
>>> conclusions from them. As the 
>>> sample size goes down, you no longer have a 2 to 4 x 10^-11 beast, it’s 
>>> more like 5X that.
>>> 
>>> Bob
>>> 
>>> 
>>>> On Jan 12, 2017, at 11:31 AM, Bob Stewart  wrote:
>>>> 
>>>> Hi Bob,
>>>> Normally I see somewhere between 2E-11 and 4E-11 at 1S tau on my 5370A, as 
>>>> in the blue trace on the attached plot.  Am I misunderstanding your 
>>>> meaning?  Granted, I am clocking the 5370A with a GPSDO, but I believe I 
>>>> see about the same thing with the HP10811.  This test was 1PPS vs 1PPS on 
>>>> two different units.
>>>> The plot also has a test run by Tom, in orange, using his H Maser and a 
>>>> Timepod to show how poor the 5370 is compared to the Timepod below about 
>>>

Re: [time-nuts] General questions about making measurements with time interval counter.

[Bob Camp]

Hi

Keep in mind that when you do 1800 samples at 1 second, that data will only 
meet the 
100 sample requirement out to tau = 18 seconds. Past that you are in the “under 
100 samples
region”.

Bob

> On Jan 12, 2017, at 2:32 PM, Bob Stewart  wrote:
> 
> Hi Bob,
> OK, thanks for explaining.  When you and others use highly technical terms 
> like "small number of samples" it's not always clear to me what you mean.  =) 
>  Ten samples?  That's not enough for anything.  Normally I run at least 1800 
> samples; at least if I plan to share them with someone.
> 
> Bob -
> AE6RV.com
> 
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> 
>  From: Bob Camp 
> To: Bob Stewart ; Discussion of precise time and frequency 
> measurement  
> Sent: Thursday, January 12, 2017 1:03 PM
> Subject: Re: [time-nuts] General questions about making measurements with 
> time interval counter.
> 
> Hi
> 
> It varies from 5370 to 5370. You see a lot of plots that run out to 10 
> samples or less. Anything below 100 samples
> is risky in some senses.
> 
> Bob
> 
>> On Jan 12, 2017, at 12:25 PM, Bob Stewart  wrote:
>> 
>> Hi Bob,
>> OK, what's a small number of data points?  Attached is a screencap of 
>> captures for 25, 50, 75, 100, and 150 seconds.  Yeah, at 25 seconds, the 1S 
>> tau is up at 4.56E-11, but it falls pretty quickly.  I will mention that 
>> this particular 5370 is much better than my other one.  So, maybe this one 
>> is an exceptional example?
>> 
>> Just for grins, I also included a screencap of the phase points.
>> 
>> Bob -
>> AE6RV.com
>> 
>> GFS GPSDO list:
>> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>> 
>>   From: Bob Camp 
>> To: Bob Stewart ; Discussion of precise time and frequency 
>> measurement  
>> Sent: Thursday, January 12, 2017 11:04 AM
>> Subject: Re: [time-nuts] General questions about making measurements with 
>> time interval counter.
>> 
>> Hi
>> 
>> There is a big difference between RMS and single shot. Single shot, the 5370 
>> is a very different beast. 
>> That’s not a big deal when you have a few thousand readings and it all 
>> averages down. Unfortunately 
>> we all love to do runs with a very small number of points and then draw 
>> conclusions from them. As the 
>> sample size goes down, you no longer have a 2 to 4 x 10^-11 beast, it’s more 
>> like 5X that.
>> 
>> Bob
>> 
>> 
>>> On Jan 12, 2017, at 11:31 AM, Bob Stewart  wrote:
>>> 
>>> Hi Bob,
>>> Normally I see somewhere between 2E-11 and 4E-11 at 1S tau on my 5370A, as 
>>> in the blue trace on the attached plot.  Am I misunderstanding your 
>>> meaning?  Granted, I am clocking the 5370A with a GPSDO, but I believe I 
>>> see about the same thing with the HP10811.  This test was 1PPS vs 1PPS on 
>>> two different units.
>>> The plot also has a test run by Tom, in orange, using his H Maser and a 
>>> Timepod to show how poor the 5370 is compared to the Timepod below about 
>>> 60S tau.  These are essentially apples vs apples tests.
>>> 
>>> Bob
>>> 
>>> 
>>> 
>>> 
>>>   From: Bob Camp 
>>> To: Discussion of precise time and frequency measurement 
>>>  
>>> Sent: Thursday, January 12, 2017 8:27 AM
>>> Subject: Re: [time-nuts] General questions about making measurements with 
>>> time interval counter.
>>> 
>>> Hi
>>> 
>>> There are a number of ways to improve the resolution (and accuracy) of your 
>>> data without spending 
>>> big piles of cash. They have been discussed here on the list many times 
>>> over the last few years. 
>>> What I’m suggesting is that you dig into that ahead of taking data. You 
>>> will dive into it eventually as you 
>>> look more and more at devices that are locked to some sort of stable 
>>> reference internally. 
>>> 
>>> Ideally you would like a device with a floor 5X to 10X better than what you 
>>> are measuring. For ADEV style
>>> data, the 5370 is a 1x10^-10 sort of device single shot (so 1x10^-9 is the 
>>> limit at 10:1). With a lot of averaging 
>>> (which is not something you do with ADEV) you can get about 5X better than 
>>> that as a floor. In either case, it is getting in the way of any
>>> readings that are much below 1x1

Re: [time-nuts] General questions about making measurements with time interval counter.

[Bob Camp]

Hi

It varies from 5370 to 5370. You see a lot of plots that run out to 10 samples 
or less. Anything below 100 samples
is risky in some senses.

Bob

> On Jan 12, 2017, at 12:25 PM, Bob Stewart  wrote:
> 
> Hi Bob,
> OK, what's a small number of data points?  Attached is a screencap of 
> captures for 25, 50, 75, 100, and 150 seconds.  Yeah, at 25 seconds, the 1S 
> tau is up at 4.56E-11, but it falls pretty quickly.  I will mention that this 
> particular 5370 is much better than my other one.  So, maybe this one is an 
> exceptional example?
> 
> Just for grins, I also included a screencap of the phase points.
> 
> Bob -
> AE6RV.com
> 
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> 
>  From: Bob Camp 
> To: Bob Stewart ; Discussion of precise time and frequency 
> measurement  
> Sent: Thursday, January 12, 2017 11:04 AM
> Subject: Re: [time-nuts] General questions about making measurements with 
> time interval counter.
> 
> Hi
> 
> There is a big difference between RMS and single shot. Single shot, the 5370 
> is a very different beast. 
> That’s not a big deal when you have a few thousand readings and it all 
> averages down. Unfortunately 
> we all love to do runs with a very small number of points and then draw 
> conclusions from them. As the 
> sample size goes down, you no longer have a 2 to 4 x 10^-11 beast, it’s more 
> like 5X that.
> 
> Bob
> 
> 
>> On Jan 12, 2017, at 11:31 AM, Bob Stewart  wrote:
>> 
>> Hi Bob,
>> Normally I see somewhere between 2E-11 and 4E-11 at 1S tau on my 5370A, as 
>> in the blue trace on the attached plot.  Am I misunderstanding your meaning? 
>>  Granted, I am clocking the 5370A with a GPSDO, but I believe I see about 
>> the same thing with the HP10811.  This test was 1PPS vs 1PPS on two 
>> different units.
>> The plot also has a test run by Tom, in orange, using his H Maser and a 
>> Timepod to show how poor the 5370 is compared to the Timepod below about 60S 
>> tau.  These are essentially apples vs apples tests.
>> 
>> Bob
>> 
>> 
>> 
>> 
>>   From: Bob Camp 
>> To: Discussion of precise time and frequency measurement 
>>  
>> Sent: Thursday, January 12, 2017 8:27 AM
>> Subject: Re: [time-nuts] General questions about making measurements with 
>> time interval counter.
>> 
>> Hi
>> 
>> There are a number of ways to improve the resolution (and accuracy) of your 
>> data without spending 
>> big piles of cash. They have been discussed here on the list many times over 
>> the last few years. 
>> What I’m suggesting is that you dig into that ahead of taking data. You will 
>> dive into it eventually as you 
>> look more and more at devices that are locked to some sort of stable 
>> reference internally. 
>> 
>> Ideally you would like a device with a floor 5X to 10X better than what you 
>> are measuring. For ADEV style
>> data, the 5370 is a 1x10^-10 sort of device single shot (so 1x10^-9 is the 
>> limit at 10:1). With a lot of averaging 
>> (which is not something you do with ADEV) you can get about 5X better than 
>> that as a floor. In either case, it is getting in the way of any
>> readings that are much below 1x10^-9 at one second. A low cost XO can hit 
>> that level of performance.  
>> 
>> Bob
>> 
>> 
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>> and follow the instructions there.
> 
> 
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Re: [time-nuts] General questions about making measurements with time interval counter.

[Bob Camp]

Hi

There is a big difference between RMS and single shot. Single shot, the 5370 is 
a very different beast. 
That’s not a big deal when you have a few thousand readings and it all averages 
down. Unfortunately 
we all love to do runs with a very small number of points and then draw 
conclusions from them. As the 
sample size goes down, you no longer have a 2 to 4 x 10^-11 beast, it’s more 
like 5X that.

Bob


> On Jan 12, 2017, at 11:31 AM, Bob Stewart  wrote:
> 
> Hi Bob,
> Normally I see somewhere between 2E-11 and 4E-11 at 1S tau on my 5370A, as in 
> the blue trace on the attached plot.  Am I misunderstanding your meaning?  
> Granted, I am clocking the 5370A with a GPSDO, but I believe I see about the 
> same thing with the HP10811.  This test was 1PPS vs 1PPS on two different 
> units.
> The plot also has a test run by Tom, in orange, using his H Maser and a 
> Timepod to show how poor the 5370 is compared to the Timepod below about 60S 
> tau.  These are essentially apples vs apples tests.
> 
> Bob
> 
> 
> 
> 
>  From: Bob Camp 
> To: Discussion of precise time and frequency measurement  
> Sent: Thursday, January 12, 2017 8:27 AM
> Subject: Re: [time-nuts] General questions about making measurements with 
> time interval counter.
> 
> Hi
> 
> There are a number of ways to improve the resolution (and accuracy) of your 
> data without spending 
> big piles of cash. They have been discussed here on the list many times over 
> the last few years. 
> What I’m suggesting is that you dig into that ahead of taking data. You will 
> dive into it eventually as you 
> look more and more at devices that are locked to some sort of stable 
> reference internally. 
> 
> Ideally you would like a device with a floor 5X to 10X better than what you 
> are measuring. For ADEV style
> data, the 5370 is a 1x10^-10 sort of device single shot (so 1x10^-9 is the 
> limit at 10:1). With a lot of averaging 
> (which is not something you do with ADEV) you can get about 5X better than 
> that as a floor. In either case, it is getting in the way of any
> readings that are much below 1x10^-9 at one second. A low cost XO can hit 
> that level of performance.  
> 
> Bob
> 
> 
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Re: [time-nuts] General questions about making measurements with time interval counter.

[Bob Camp]

Hi

There are a number of ways to improve the resolution (and accuracy) of your 
data without spending 
big piles of cash. They have been discussed here on the list many times over 
the last few years. 
What I’m suggesting is that you dig into that ahead of taking data. You will 
dive into it eventually as you 
look more and more at devices that are locked to some sort of stable reference 
internally. 

Ideally you would like a device with a floor 5X to 10X better than what you are 
measuring. For ADEV style
data, the 5370 is a 1x10^-10 sort of device single shot (so 1x10^-9 is the 
limit at 10:1). With a lot of averaging 
(which is not something you do with ADEV) you can get about 5X better than that 
as a floor. In either case, it is getting in the way of any
readings that are much below 1x10^-9 at one second. A low cost XO can hit that 
level of performance.  

Bob

> On Jan 12, 2017, at 4:36 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 12 January 2017 at 02:31, Bob Camp  wrote:
> 
>> Hi
>> 
> 
> Hi Bob
> 
> 
>> 
>> The most basic issue you are going to run into is that your counter is not
>> high enough
>> resolution / accuracy to give you meaningful data for time intervals under
>> a few hundred
>> seconds.
> 
> 
> Is that true if I'm not testing very high quality sources? There are
> significant differences observed between these two setups
> 
> 1) START and STOP from distribution amplifier.
> 2) START from distribution amplifier. STOP from Stanford Research SR345 30
> MHz function generator set to produce 10 MHz.
> 
> 1) ADEV plot at http://www.kirkbymicrowave.co.uk/time-stuff/ADEV.PNG
> where ADEV is about 5x poorer on the function generator at 100 seconds
> 
> 2) MDEV plot at http://www.kirkbymicrowave.co.uk/time-stuff/MDEV.PNG
> where MDEV is about 5 x poorer on the function generator at 10 seconds.
> 
> The raw data is in the same directory
> http://www.kirkbymicrowave.co.uk/time-stuff/ . I should have zipped that,
> as it is quite large
> 
> I'm pretty sure the HP 83623A 20 GHz sweep generator will be a lot worst
> than either of those, as a simple check of the standard deviation on the
> display of the HP 5370B (no data collected from GPIB), showed much higher
> SD on the microwave sweeper than the function generator.
> 
> I can see if I were testing masers, Cs source, and decent GPS receivers,
> what you say would be true. But is it true for lesser quality sources?
> Maybe testing lesser quality sources is not such a stupid idea, as the
> instrumentation is less of a limiting factor.
> 
> I admit I did say in my original post SHORT/MEDIUM time scales, and I guess
> 10/100s is not short.
> 
> 
> 
>> I would focus on improving on that part of things before I went off on a
>> major
>> “test everything” adventure.
> 
> 
> But is there any way without spending lots of cash? The following
> instruments are out of the question due to price
> 
> * Keysight 53230A 350 MHz Universal Frequency Counter/Timer, 12 digits/s,
> 20 ps
> * John's Timepod
> 
> A Stanford Research SR620 is not out of the question. I did have one
> before, but swapped it, along with a 4.2 GHz signal generator for an
> HP4391B impedance/material analyzer. The 5370B came along fairly cheap
> ($300), but I don't mind spending more on  a SR620. But will that gain me
> much? I know the single shot resolution is a bit better than the 5370B, but
> it does not appear to be a massive improvement, given they are 3~4 x the
> cost.on the used market.
> 
> I also have many other contraiints, which limit what I can realistically
> achieve
> 
> * Small lab in my garmage- opening door on lab will change temperature.
> * Single glazed window
> * Air con that is a standard unit designed for offices - not metrology
> labs.
> 
> Simply collecting a lot of data that is resolution limited is
>> not a lot of fun …..
>> 
> 
> Agreed. But am I doing that at > 10 seconds? Is the counter my limit on
> those two sets of data? I will collect some from the HP 83623A 20 GHz sweep
> generator later today, but that generates a lot of heat, and I'd rather let
> that warm up for a couple of hours before doing anything with that.
> 
> 
>> 
>> Bob
>> 
> 
> You clearly have a lot of knowledge Bob. Can I learn anything useful with
> what I have, or am I wasting my time?
> 
> Dave
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Re: [time-nuts] General questions about making measurements with time interval counter.

[Bob Camp]

Hi

The most basic issue you are going to run into is that your counter is not high 
enough
resolution / accuracy to give you meaningful data for time intervals under a 
few hundred
seconds. I would focus on improving on that part of things before I went off on 
a major
“test everything” adventure. Simply collecting a lot of data that is resolution 
limited is 
not a lot of fun …..

Bob

> On Jan 11, 2017, at 9:20 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> MY AIMS
> 
> 1) Try to learn about the various statistical tests (ADEV, MDEV etc), and
> how best to compare oscillators, by making some measurements on various
> oscillators I have.
> 
> 2) Investigate the short/medium term stability of the output of  various
> bits of test kit. All are locked to GPS by feeding 10 MHz to their timebase
> inputs, so long term drift should not be relevant.
> 
> These istrumuments are:
> 
> a) The GPS itself - primarily a test of the 5370B time interval counter,
> distribution amplifier and general temperature fluctuations in the lab.
> 
> b) Other GPS(s) when I get 1 or 2 more.
> 
> c) 10 MHz to 20 GHz Microwave signal generator.
> 
> d) 0.001 Hz to 30 MHz function generator.
> 
> e) A VNA that will work at 10 MHz. Turn sweeping off
> 
> f) A VNA that has a minimum frequency of 50 MHz. Again turn sweeping off.
> 
> METHOD - Suggestion for improvements welcome.
> 
> * Where possible set all instruments to 10 MHz, which is the same as the
> GPS reference. (Obviously since one of the VNAs will not go below 50 MHz, I
> would need to use a higher frequency)
> * Feed GPS to the start input of the 5370B TI counter and the DUT into the
> stop input
> * Use the 5370B time interval counter to measre the time difference between
> one output of the distribution amplifier and the output of the instrument
> being tested .
> * Collect data from 5370B and use John's Timelab to plot various graphs and
> try to understand the differences between the various statical measurements
> (ADEV, MDEV etc.)
> 
> MY QUESTIONS.
> 
> 1) Should I use the GPS to provide a reference for the 5370B time interval
> counter,  or would it be better to use the internal OCXO? Currently I have
> the 5370B locked to GPS too, but I am wondering if this is a bad idea and I
> should run it from its own oscillator.
> 
> 2) Is there any advantage in a 10 MHz DUT going into the start or stop
> input? I assume that it is irrelevant, as long as the GPS goes into the
> other. But maybe not.
> 
> 3) If the DUT is higher in frequency (eg 50 MHz) than the 10  MHz GPS,  is
> there any advantage in going in the start ot stop input?
> 
> 4) If the DUT is lower in frequency (eg 5 MHz) than the 10  MHz GPS,  is
> there any advantage in going in the start ot stop input?
> 
> Dave
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

The obvious question would be: What does it cost to set up a line to make a 
proper
set of spherical Rb cells? Doing this as a glassblowing project is a dead end. 
You
need it properly tooled ….

Bob

> On Jan 11, 2017, at 7:05 PM, Bruce Griffiths  
> wrote:
> 
> Angus
> Read the paper I posted on the current state of the art.
> ADEV ~ 2E-13/SQRT(Tau) is feasible with large cells and using a laser instead 
> of rubidium lamp.In principle, one can use the same cell to lock the laser to 
> the rubidium absorption line and lock the microwave signal.Suitable laser 
> diodes are readily available.
> Increasing the contrast of the signal used for locking reduces the noise 
> significantly.One approach is to use an integrating sphere cell and use an 
> optical fibre to bring the laser signal into the cell.Since random scattering 
> in an integrating sphere depolarises the light and virtually eliminates any 
> effect of spatial coherence a multimode fibre should suffice.Laser speckle 
> can be reduced significantly by using a colloidal suspension of titanium 
> dioxide if the colloidal suspension fills another integrating sphere or 
> equivalent.I've tried the latter using plastic optical fibres to transport 
> the laser light into and out of the colloid. Its extremely effective in 
> eliminating speckle in an optical interferometer.
> Bruce 
> 
>On Thursday, 12 January 2017 12:19 PM, Angus  
> wrote:
> 
> 
> On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:
> 
>> 
>> This does get back to state of the art Rb and what that means. In my 
>> suggested case thats measured in terms of ADEV for Tau = 1 to 1,000,000 
>> seconds. If you wanted an Rb with (only) state of the art phase noise at 1 
>> MHz offset … thats a different thing. State of the art for 
>> power consumption and size is also not what Im suggesting in this case. Why 
>> the choice of spec? … this is TimeNuts. 
> 
> Hi,
> 
> Some discussions on the performance that might be practically achieved
> with different designs may be a useful start - as long as it's done in
> the context of a practical unit that could actually get built, rather
> than just a theoretical wish list.
> 
> It would also be good to have some idea of the cost of any special
> parts like cells too. Without that info, it's hard to know how
> practical particular designs would be. 
> 
> Looking at export/technology controls might be useful early on too,
> since we're going for high performance.
> 
> I've often wondered how a 21st century version of a 5065 would
> perform, so it's great to see that I'm not completely alone in my
> insanity!
> 
> Angus.
> 
> 
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 11, 2017, at 6:07 PM, Angus  wrote:
> 
> On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:
> 
>> 
>> This does get back to “state of the art Rb” and what that means. In my 
>> suggested case that’s measured in terms of ADEV for Tau = 1 to 1,000,000 
>> seconds. If you wanted an Rb with (only) state of the art phase noise at 1 
>> MHz offset 
> that’s a different thing. State of the art for 
>> power consumption and size is also not what I’m suggesting in this case. Why 
>> the choice of spec? 
> this is TimeNuts. 
> 
> Hi,
> 
> Some discussions on the performance that might be practically achieved
> with different designs may be a useful start - as long as it's done in
> the context of a practical unit that could actually get built, rather
> than just a theoretical wish list.
> 

The biggest issue with doing this is that *if* there is a magic formula that 
tells you 
“these parts give you that ADEV” …. it’s in the same vault as the formula for 
Coke. 
That sort of thing (if it even exists) would be the gold standard of corporate 
IP for
a company making atomic clocks. 

About all you can really say is “they did this and the units the shipped did 
that”. There
are some obvious thing like “bigger cells work better”. Coming up with an 
equation that
correctly predicts a cell of this odd geometry functioning at these dimensions 
for 10,000
second ADEV ….not so much. 

> It would also be good to have some idea of the cost of any special
> parts like cells too. Without that info, it's hard to know how
> practical particular designs would be. 

The most likely course would be to cut out a major chunk of cost and find 
somebody
who is willing to make up a couple hundred sets of cells. There has already been
a proposal to do this floated on the list. I don’t recall the exact numbers, 
but $2,000
is what comes to mind. Apologies if this is a bogus number. 

> 
> Looking at export/technology controls might be useful early on too,
> since we're going for high performance.

Indeed, if you get to crazy you could get in trouble. My guess is that a 
standard the 
size of a 5065 or larger is unlikely to set off alarm bells. 


> 
> I've often wondered how a 21st century version of a 5065 would
> perform, so it's great to see that I'm not completely alone in my
> insanity!

Which obviously is an itch many of us share. The gotcha of course is that each 
of 
us has (likely incompatible) ideas about how to do it. We may even have 
incompatible goals in terms of “what’s good”. Based on many decades of 
designing 
things like this, feature creep and elastic goals will kill a project dead 
(usually after
a lot of money has been spent). 

Lots of Fun

Bob

> 
> Angus.
> 
> 
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

A spherical set of cells is going to be a massive pain to fabricate. I believe 
you can hit < 5x10^-12 / sqrt(tau) with 
a fairly normal cell design and cavity design. There are some very basic issues 
with the photo detector’s S/N that
also tip things towards a coaxial approach.

Bob

> On Jan 10, 2017, at 10:43 PM, Bruce Griffiths  
> wrote:
> 
> A  spherical cavity resonator with a spherical Rubidium cell configured as an 
> integrating sphere (to enhance the SNR of the optical absorption signal) is a 
> potential option. Its also possible to use the same cell to lock a 795 nm 
> laser to the desired wavelength. Fiber coupling the laser light could also be 
> useful.Note that with an integrating sphere (or any other random scattering 
> process eg scattering from colloidal particles undergoing Brownian motion) 
> laser polarisation isn't preserved which may be convenient.One potential 
> issue with an  integrating sphere is the longevity of the diffusing coating 
> (typically Barium sulphate with an organic binder). Roughening (fine grind  
> followed by HF etch for stress relief) the outer surface of the cell is also 
> advisable to eliminate light pipe effects in the cell wall.
> Bruce 
> 
>On Wednesday, 11 January 2017 3:54 PM, Bruce Griffiths 
>  wrote:
> 
> 
> A goal with ADEV ~ 1E-13/Tau (for Tau <1000sec) may be feasible as its 
> already been done as part of a PhD thesis.Using as large a cavity as possible 
> is probably useful so that a large cell can be employed.What resonant mode is 
> desirable in the cavity?Do we need to avoid field reversal as in the hydrogen 
> maser?
> Bruce  
> 
>On Wednesday, 11 January 2017 3:43 PM, Bob Camp  wrote:
> 
> 

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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

A cryo pump will get you into reliability issues if run 24/7. It also is 
doubtful 
that you will be able to maintain the vacuum level over long periods.

Bob

> On Jan 11, 2017, at 12:09 AM, Bruce Griffiths  
> wrote:
> 
> One could always use a cryo pump.
> The following paper is a summary of the current state of the art for rubidium 
> vapour frequency 
> standards:http://www.euramet.org/Media/docs/Repository/A169/IND55/micalizio_02182015.pdf
> 
> Bruce 
> 
>On Wednesday, 11 January 2017 5:15 PM, Ole Petter Ronningen 
>  wrote:
> 
> 
> Add to this ion-pumps (in the case of EFOS type masers 2 every ~2 years),
> plus substantial tooling (turbomolecular vacuum pump, anyone?) to service
> the thing - unless you want the manufacturer to do so..
> 
> Ole
> 
> On Tue, Jan 10, 2017 at 11:12 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>> On 10 January 2017 at 15:35, Ole Petter Rønningen 
>> wrote:
>> 
>>> ... having said that, I for one think I'm with Bob on this one. The thing
>>> about masers are that they are big. At least active masers. And they
>>> require a substantial volume be kept at ultra high vacuum - which is not
>>> trivial, especially not in a homeshop. The cavity needs to be kept at a
>>> temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
>>> this costly pumps to keep the vacuum this low even if you succeed at
>>> reaching that vacuum.. There's easily 1-2KUSD running cost per year just
>> to
>>> keep the maser running.
>>> 
>> 
>> Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
>> maser has a peak power of 150 W and an operating power of 75 W.  Based on a
>> power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
>> £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
>> believe electricity is cheaper in the USA than here in the UK, but
>> converting £131 (GBP) to USD, that's around $161/year in electricity.. So
>> running costs don't seem to be an issue.
>> 
>> But I must admit, the thought of spending a lot of time/money to build
>> something I could have bought for a lot less with higher performance is not
>> that attractive, although of course there would be a satisfaction from
>> building it yourself.
>> 
>> Dave
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

I suspect that there are (or will be) some other cheaper / easier ways to do 
the same thing. The signal to noise requirements 
in the RF chain are sensitive to a couple of things, but not to an absurd 
level. You do need good close in noise. I would not even bother to 
go for a “final” RF section until the physics stuff had been worked out. 
Designing today vs designing in a couple
of years will always be the more expensive approach. For the lash up, I might 
well gut parts out of an existing
cheap Rb simply to get things going …. who knows. Maybe we would need a chain 
like the one in the paper to figure out 
what is going on.  In four  years take a look at what is on the market and make 
some decisions about the “final” RF chain. 
Even then you might revisit it several years after that due to cost or 
performance issues….

This does get back to “state of the art Rb” and what that means. In my 
suggested case that’s measured in terms of ADEV for Tau = 1 to 1,000,000 
seconds. If you wanted an Rb with (only) state of the art phase noise at 1 MHz 
offset … that’s a different thing. State of the art for 
power consumption and size is also not what I’m suggesting in this case. Why 
the choice of spec? … this is TimeNuts. 

For some guidance on what state of the art in Rb’s *is* in this area, check out 
the many papers on the GPS Rb’s published in in the ION conference proceedings. 
Can a bunch of hackers do quite that well? … likely not. They have been 
fiddling with that design for many decades. They also have a pretty healthy 
budget to 
produce each one they build. We certainly can try to get as close as we can. 
Testing ours in orbit *might* put a strain on the budget though :)

Bob

> On Jan 10, 2017, at 9:15 PM, Bruce Griffiths  
> wrote:
> 
> A possible RF chain for a Rubidium standard using off the shelf parts plus a 
> couple of custom microwave filters:https://arxiv.org/pdf/1204.4215.pdf
> 
> Bruce 
> 
>On Wednesday, 11 January 2017 2:10 PM, Bob Camp  wrote:
> 
> 
> Hi
> 

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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

The gotcha is that 5065’s never were a popular item in HP’s lineup. As a 
result, they are fairly sparse in the surplus market. Those who need them
for this or that application gobble them up on a regular basis. Trying to do 
up a couple hundred “improved” 5065’s just isn’t going to happen (at least 
without driving the current price up by > 10X or 100X). 

Since about the only thing you keep from the 5065 once you are done is the
physics package, that’s a big payout for very few usable parts. You then 
modify (and possibly repair) the physics package. If we ever get into this, you
also replace a few parts in there to improve it’s performance. Now you have
even fewer “keeper” parts. 

Simple approach:

Decide you want a state of the art Rb (what other goal would there be?) 
Organize the team
Work out a first pass design
Find a source for *large* Rb cell sets.
Work with them to get the cells right
Design up a physics package in parallel with this effort
Get it all prototyped multiple times and debugged with lash up electronics
Test for about a year once you have the prototype debugged
Order up the tooling on the long lead stuff (cells and some machined parts)
Get the real electronics working in some form
Debug the electronics against the real cells and parts
Test for about a year once you think it’s working
Do the real layouts and packaging, including shielding and all the other nasty 
stuff
Fit up the first unit 
Test for about a year to be sure you have caught all the issues
Redo what is needed
Start building the hundred or so units on order with the cash on hand from 
those orders.

Lots of fun !!

I’m sure somebody will chime in at this point and claim they can do that all 
for about $100 a unit. If so feel free to try. It’s simply liars poker at that 
point
since nobody ever has to actually do it. Based on having done it and on having
seen others do it … it is not at all cheap to do. Rb *is* cheaper, but it’s 
still not free. 

You might also question the “test for a year” stuff. If you want ADEV style 
data that has
any meaning, you need sample sizes that are in the 10 to 100X tau range. For a 
one
week tau, each run will be > 3 months.  Testing takes time…..You also need to be
testing multiple units to get any confidence. That takes money.

Even more fun.

Bob


> On Jan 10, 2017, at 7:40 PM, Gregory Maxwell  wrote:
> 
> On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq  wrote:
>> I have a pile of stuff. You have a pile of stuff. Others each have their 
>> pile of stuff. Doing
>> a design that works only with my pile is possible. Doing a design that works 
>> with my pile
> [...]
>> You have to do it with a fairly standardized
>> design. That means buying (at the very least) kits of parts. Like it or not, 
>> the parts kit for a
>> Rb will be cheaper than the parts kit for any of the other devices…..
> 
> I read the occasional posts by PHK on his efforts to upgrade the
> electronics in his 5065a and Corby's SUPER physics package upgrade
> with great interest.  I have wondered if the end result may be that
> incremental upgrades to someone elses classic design, adding on modern
> synthesizers and digital control, etc. Might eventually result in a
> 'Ship of Theseus' oscillator, which in its final form is buildable
> from relatively easily sourced parts (plus perhaps a rubidium cell
> that could be group bought at non-absurd prices).
> 
> Presumably taking an already established design and improving it
> incrementally has lower risk and costs than a new design. In
> particular, it can start off with 5065a as "my pile" inputs, but by
> the end it doesn't have them anymore... and not just lest risky but
> also a more natural way to divide the effort up into less
> professionally-sized chunks.
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>> 
>> Hi
>> 
>> Ok here are some rough numbers:
>> 
>>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>>> It would be interesting to see your breakdown of the costs and man hours
>>> for an H2 maser. I suspect that others would find cheaper/faster
> solutions.
>> 
>> $100M for the H2
>> 
>> $25M for the Rb
> 
> With all due respect,  and I apprectiate you have a good knowledge of this
> field, but that's not a breakdown of costs or man hours I wanted to see,
> but a cost which appears to be plucked from the air.

Hardly plucked from the air. The last Rb design that I was involved with was 
roughly 5X that expensive. 

> 
> There's a BIG difference between a volunteer effort where
> 
> * Salaries are not paid
> * Items of test equipment are likely to be borrowed or people provide
> access to them for no charge etc,
> * Academics are likely to provide consultancy for free, in return for being
> on papers published.
> * Software licenses could probably be obtained free,  or enough people get
> trials.

That’s where the 5:1 cost reduction comes from. 

> 
> compared to a commercial company building a maser where
> 
> * Salaries are paid
> * All equipment is purchased new
> * Bench power supplies with 3.5 digit displays are sent out for calibration
> each year.
> *  No outside body will do anything except at a commercial rate.
> * Flights are booked for meetings which could be done over the Internet.
> * High end software licenses are huge.
> 
>> $500M for the fountain.
> 
> But on what basis do you arrive at that figure?

The numbers that the people who have done it come up with when you talk to 
them. 

> 
>> To get sponsorship for anything remotely close to those numbers, you
>> need to have some massively good credentials.
>> 
>> Bob
> 
> Yes agreed at $500M. But someone like Tom, who does have massively good
> credentials, could perhaps get $500,000, and perhaps that wisely spent
> could get a fountain built.  Without knowing how you arrive at $500M, it is
> not possible for anyone to look at ways of shaving that cost.


This is *not* a cheap field to be doing things in ….

Bob

> 
> The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
> budget. It was at the time the world's  largest steerable radio telephone.
> Half a century later only 2 larger ones have been built.
> 
> Maybe I am too nieve.
> 
> Dave.
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi 

Ok here are some rough numbers:

> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 8 Jan 2017 17:34, "Bob Camp"  wrote:
> 
>> You are talking about a project that will take many years and likely
>> more money than the price of a new home. If that is “fun money”, then
>> fine. For most people that sort of commitment is a bit outside the range
>> of do it for fun.
> 
> It would be interesting to see your breakdown of the costs and man hours
> for an H2 maser. I suspect that others would find cheaper/faster solutions.

$100M for the H2

$25M for the Rb

> 
>> Even as a “fun project”, I question the bang for the buck. If cost and
> time
>> are no object, why not do an optical ion standard or a Cesium fountain?
>> I would suggest that both are more cool than than a maser and likely
>> have a lot more fun aspects to them. You then would have something
>> truly unique and not simply a more expensive / poorer performing example
>> of something you could have bought.
> 
> You raise an interesting point.
> 
> I suspect that if a serious attempt was made at a caesium fountain by a
> *group* of people, they might end up with donated parts from places like
> NIST, NPL etc.
> 
> Commercial sponsorship  could conceivability be an option to funding such a
> project, as could wealthy individuals like Richard Branson or James Dyson,
> both of whom are interested in technically challenging projects.
> 
> $100 would not go far, but I personally would be willing to donate $100
> towards the cost of such a project, just to feel part of it.

$500M for the fountain. 

To get sponsorship for anything remotely close to those numbers, you 
need to have some massively good credentials. 

Bob

> 
>> Bob
> 
> Dave
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 9, 2017, at 1:05 AM, Bruce Griffiths  
> wrote:
> 
> For a rubidium vpour standard a cavity is essential, one could always use a 
> microwave horn to illuminate the cell in an anechoic chamber.


The cavity in an Rb is not the ultra high Q monster that you have in a Maser. 
There is 
no magic “minimum Q” requirement to get the beast to work. That’s by no means 
saying
that the cavity is unimportant or trivial. The point is only that it’s about 2 
orders of magnitude
easier to make up the required cavity for the Rb.

It should be noted that cavity != shielding and that cavity != temperature 
control. It is simply 
the microwave resonant structure that gets the electromagnetic doing the right 
thing. In both
cases you still need (very) good magnetic shielding, pressure shielding, and 
temperature 
control. In the Rb case, you need to set up specific temperatures to get things 
to work in
each cell. In the Maser case you simply need the “right” temperature for your 
setup. 

Traditionally one of the big deals about both devices was the synthesizer 
required to convert
the physics based frequency to something useful. With the Maser the frequency 
is pretty
much always the same number. That gives a simpler synthesizer in terms of 
tuning. A whole
raft of this and that give you a range of answers for the Rb. That used to make 
the synthesizer
a bit of  a pain to design. These days, the synthesizer tuning the Rb requires 
is easily done with
a cheap DDS chip. Take a look at the 5065 manual if you want to see how much 
fun that
used to be …

Indeed the whole electronics side of both standards is easier than it once was. 
The temperature
probes in the compact Maser still are $1K each, but most of the parts you need 
on the electronics
side are pretty common items. Again, common parts != trivial design. You still 
need to get the
details right. Signal to noise *does* matter. You need to use the right design 
with the right parts. 

So how do you do this? The normal approach is to get a dozen or so people 
together and work 
on it 40 hours a week for about 5 years. You build up a series of batches of 
prototypes and 
get to the point you believe you have a design (1 in 10 sort of works). You 
then spend roughly 
another three to five years knocking the rough edges off of that design and 
making the first 
batch of real units. Beyond time and people there is the cost of parts, 
software licenses, normal
test gear, really weird test gear, and all the other stuff.  This assumes it is 
run as a business with
somebody managing the whole thing. Try to run it as a committee of the whole, 
both the cost
and the time will go up. Try to do it without the right tools, at lest the time 
will go up. I’d bet
the cost will go up as well…

Bob

> Using an integrating sphere can enhance the contrast of the optical signal 
> significantly.
> 
> http://www.princeton.edu/physics/graduate-program/theses/theses-from-2011-1/bmcguyer_dissertation.pdf
> 
> https://infoscience.epfl.ch/record/178228/files/IFCS_Invited_Talk_Finalpdf.pdf
> 
> https://doc.rero.ch/record/32317/files/2318.pdf
> 
> http://tf.nist.gov/general/pdf/1154.pdf
> 
> http://tf.boulder.nist.gov/general/pdf/1663.pdf
> 
> 
> Bruce
> On Sunday, January 08, 2017 10:20:33 PM Bruce Griffiths wrote:
>> Possible sources of Rubium vapour
>> 
> cells:https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1470
>> 
>> http://www.precisionglassblowing.com/custom-solutions/optical-glassware/vapo
>> r-wavelength-reference-cells/
>> 
>> https://www.sacher-laser.com/home/lab-equipment/spectroscopy/reference_gas_a
>> nd_vapor_cells/reference_gas_and_vapor_cells.html
>> 
>> 
>> Bruce
>> 
>>On Monday, 9 January 2017 11:14 AM, Bruce Griffiths
>>  wrote:
>> 
>> 
>> Bob
>> As long as one stays away from CPT and merely uses the laser as a
>> replacement for the traditional rubidium lamp plus filters it should be
>> easy enough as one doesnt need to modulate the laser at 3.4 GHz.I was
>> thinking something along the lines of the recent PhD thesis that gave all
>> the detail required to duplicate their low noise rubidium standard that 
> was
>> quieter than am HP5065.One could easily substitute ones own ECDL 
> (These can
>> easily be constructed from commercially available parts) and improve
>> somewhat on the performance (The oven design of most commercial 
> ECDLs seems
>> suboptimal). Bruce
>> 
>>On Monday, 9 January 2017 10:23 AM, Bob Camp  
> wrote:
>> 
>> 
>> Hi
>> 
>> The large diameter Rb cells are a bit harder to come by than the more
>> generic telecom sized cells. I suspect you are correct and they are out
>> there from somebody.. The real advantage you would have with an Rb 

Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 8, 2017, at 11:57 AM, William H. Fite  wrote:
> 
> Bob, I think you're missing the point here. This is not the quest for
> utimate standards of accuracy/precision/resolution, it Is not about
> economic viability, or even attainability, let alone being "worth the
> trouble.".
> 
> It is about a fun project. Fun even if it comes to nothing. Is that
> difficult to understand?

You are talking about a project that will take many years and likely 
more money than the price of a new home. If that is “fun money”, then
fine. For most people that sort of commitment is a bit outside the range
of do it for fun. 

Even as a “fun project”, I question the bang for the buck. If cost and time
are no object, why not do an optical ion standard or a Cesium fountain?
I would suggest that both are more cool than than a maser and likely 
have a lot more fun aspects to them. You then would have something 
truly unique and not simply a more expensive / poorer performing example
of something you could have bought. 

Having been down this road before, there is a *lot* of physics involved
in any of these standards. You may not quite do the work to earn ( possibly 
another) Phd in Physics, but if you do it alone, the learning will be close. 

I’m by no means saying don’t do it. That is very much up to the individual
to decide. What I’m saying is that to have any chance of completing the 
project, you need to face up to the costs (both money and time) up front. 
If you don’t, this will simply become an exercise in thrashing around. 

Bob


> 
> 
> 

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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 8, 2017, at 11:21 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 8 January 2017 at 15:22, Bob Camp  wrote:
> 
>> Hi
>> 
>> I guess the question then would be:
>> 
>> Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
>> 
>> With 100 KHz / C temperature coefficients running around, getting
>> good stability in a real world setting at 1 day will be “interesting”.
>> 
>> Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
>> 1 second for the “cheap” version and 8x10^-14 at one second for
>> the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
>> 1 second is running around on various web sites.
>> 
>> The NIST paper suggests that they made several prototypes before
>> they got one good one working. That’s a lot of “fun and games” with
>> ceramic machine lathes and Rb magnetometers…..
>> 
>> The punch line being - would the same effort / cost / many years of time
>> be more
>> fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
>> the number of people making them in volume over the years, Rb’s appear to
>> be the easier item to debug, design, and build.
>> 
>> Bob
>> 
> 
> If you build a H2 maser, you would learn a lot more than building a bunch
> of rubidiums. That sounds a good enough reason to me.


I’m not sure I agree with that. Both have their own issues. Much of the learning
in both cases involves fiddly mechanical and machining details. Working each
out by a lot of trial and error would be useful for that particular standard. 
It’s hard
to see how it would be useful for much else …. Yes, there is a bunch of obscure
physics involved in each, but again it’s very use specific stuff. 

Bob

> 
> I've been contemplating buying one of the older HP 5061A or 5061B cesium
> frequency standards from eBay. Almost all are sold as "for spares or
> repair", and are probably not going to be economically viable to get
> working due to the fact the tubes are probably useless. But I'd sure learn
> a lot from playing around inside one of the older ones.
> 
> Dave
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

I guess the question then would be: 

Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble? 

With 100 KHz / C temperature coefficients running around, getting 
good stability in a real world setting at 1 day will be “interesting”. 

Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at 
1 second for the “cheap” version and 8x10^-14 at one second for
the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
1 second is running around on various web sites. 

The NIST paper suggests that they made several prototypes before
they got one good one working. That’s a lot of “fun and games” with
ceramic machine lathes and Rb magnetometers…..

The punch line being - would the same effort / cost / many years of time be more
fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
the number of people making them in volume over the years, Rb’s appear to 
be the easier item to debug, design, and build. 

Bob


> On Jan 8, 2017, at 6:01 AM, Bruce Griffiths  
> wrote:
> 
> You could try a cavity like the one in;http://tf.nist.gov/general/pdf/156.pdf
> 
> This avoids the requirement for a fused quartz storage bulb.
> Bruce 
> 
>On Sunday, 8 January 2017 11:33 PM, timeok  wrote:
> 
> 
> 
> Hi,
> the thought of being able to work on building a H Maser has always 
> accompanied me in recent years.
> I fully understand the many difficulties of this project and also the 
> necessity of a work team.
> Maybe a Passive Maser would be easiest to implement, but I do not know in 
> detail the processes
> of construction of the physical part of the interrogation.
> Honestly, I would love to spend My next ten years on a project like this, 
> but...
> my curiosity is to know of there are other people with these mental disorders 
> on earth.
> 
> If you want to answer me.
> Luciano
> www.timeok.it
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Re: [time-nuts] Survey plot as art.

[Bob Camp]

Hi

There is a *lot* of difference between how various receiver architectures 
respond to multipath. 
You can spend hours of “quality time” looking into the various claims of people 
having completely 
eliminated muitipath by this or that software trick.

Bob

> On Jan 7, 2017, at 4:31 PM, Peter Reilley  wrote:
> 
> In my case (the original post) there can be no multipath difference, same 
> antenna and done at the same time.
> The length of the cables from the amplified splitter are about the same; 
> within inches.
> This must be some difference in the receiver, perhaps in the math?
> 
> Pete.
> 
> On 1/7/2017 4:16 PM, Bob Camp wrote:
>> Hi
>> 
>> In terms of multipath at GPS frequencies, a couple of inches is a *lot*. 
>> Also unless you have
>> pretty good antennas (as in much larger than 1” each) they will have phase 
>> issues unique
>> to each antenna. Phase cancellation and addition is what gives you multipath.
>> 
>> Bob
>> 
>>> On Jan 7, 2017, at 4:00 PM, Gary E. Miller  wrote:
>>> 
>>> Yo Bob!
>>> 
>>> On Sat, 7 Jan 2017 15:16:34 -0500
>>> Bob Camp  wrote:
>>> 
>>>> The “simple” answer is that the weird legs going out from the central
>>>> blob are the result of multi-path / reflections in the received
>>>> signal. With enough data you might be able to correlate them to
>>>> observed obstructions.
>>> I have lots of data from GPS with the antennas mounted 1 inch apart.
>>> They show different weird legs, so I suspect that local geology/architecture
>>> is not the whole story.
>>> 
>>> For example, compare the plot I just sent, to the one attached here.
>>> Two GPS right next to each other, very differently looking plots.
>>> 
>>> I'll admit to never generating plots over the same time interval,  I'll
>>> start a 24 hour test of two GPS right now.
>>> 
>>> RGDS
>>> GARY
>>> ---
>>> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>>> g...@rellim.com  Tel:+1 541 382 8588
>>> 
>>> Veritas liberabit vos. -- Quid est veritas?
>>>"If you can’t measure it, you can’t improve it." - Lord Kelvin
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Re: [time-nuts] Survey plot as art.

[Bob Camp]

Hi

In terms of multipath at GPS frequencies, a couple of inches is a *lot*. Also 
unless you have
pretty good antennas (as in much larger than 1” each) they will have phase 
issues unique
to each antenna. Phase cancellation and addition is what gives you multipath.

Bob

> On Jan 7, 2017, at 4:00 PM, Gary E. Miller  wrote:
> 
> Yo Bob!
> 
> On Sat, 7 Jan 2017 15:16:34 -0500
> Bob Camp  wrote:
> 
>> The “simple” answer is that the weird legs going out from the central
>> blob are the result of multi-path / reflections in the received
>> signal. With enough data you might be able to correlate them to
>> observed obstructions.
> 
> I have lots of data from GPS with the antennas mounted 1 inch apart.
> They show different weird legs, so I suspect that local geology/architecture
> is not the whole story.
> 
> For example, compare the plot I just sent, to the one attached here.
> Two GPS right next to each other, very differently looking plots.
> 
> I'll admit to never generating plots over the same time interval,  I'll
> start a 24 hour test of two GPS right now.
> 
> RGDS
> GARY
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>   g...@rellim.com  Tel:+1 541 382 8588
> 
>   Veritas liberabit vos. -- Quid est veritas?
>"If you can’t measure it, you can’t improve it." - Lord Kelvin
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Re: [time-nuts] Survey plot as art.

[Bob Camp]

Hi

The “simple” answer is that the weird legs going out from the central blob are
the result of multi-path / reflections in the received signal. With enough data 
you
might be able to correlate them to observed obstructions. The simulation 
modeling 
required to make that happen might be a bit complex…..

Bob

> On Jan 7, 2017, at 3:07 PM, Gary E. Miller  wrote:
> 
> Yo Peter!
> 
> On Sat, 7 Jan 2017 12:54:45 -0500
> Peter Reilley  wrote:
> 
>> This is the survey from my Trimble NTBW50AA.   It looks like some 
>> bacteria floating around.
> 
> You can get those from any GPS using the program gpsprof from gpsd.
> 
> See attached for a 24 plot from a stationary GlobalSat MR-350P
> 
> I find these plots very useful when comparing GPS models.
> 
> RGDS
> GARY
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>   g...@rellim.com  Tel:+1 541 382 8588
> 
>   Veritas liberabit vos. -- Quid est veritas?
>"If you can’t measure it, you can’t improve it." - Lord Kelvin
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Re: [time-nuts] σ vs s in ADEV

[Bob Camp]

HI

> On Jan 5, 2017, at 6:33 AM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> On 01/05/2017 01:26 AM, Tom Van Baak wrote:
>> Hi Attila,
>> 
>> The plain ADEV calculation is essentially a measure of unexpected or
>> unwanted drift in frequency; which is the 1st difference of frequency
>> error; the 2nd difference of phase error; the 3rd difference in clock
>> time itself.
> 
> ADEV is thus sensitive to linear drift, which becomes a limiting factor for 
> higher tau.
> 

Which is *why* the standard verbal description of ADEV always includes the 
qualifier 
“drift corrected”. If drift is not removed from the data, ADEV is not doing 
what it should.
This gets overlooked when we take ADEV straight off of a cool piece of gear 
that is unable
to properly / automatically remove the drift.

Bob


> I can't see how clock time itself would integrate from phase. The time of a 
> clock is just an enumeration of phase. Phase is often presented in a wrapped 
> phase, but if you enumerate it is still just phase with larger numbers, ADEV 
> is still just 2nd difference away, not 3rd. It's actually the time of x being 
> used, not phase.
> 
>> When measuring the quality of a clock, the key idea is that initial
>> phase doesn't matter (you can always manually set the time), and even
>> initial frequency doesn't matter (you can often adjust the rate:
>> whether pendulum, quartz or atomic clock), and so a more honest
>> measure of intrinsic timekeeper stability is its ability to maintain
>> frequency; that is, statistically speaking, the lower the change in
>> frequency, tau to tau, the better. Change in frequency is frequency
>> drift.
> 
> Due to the second difference, phase offset and frequency offset does not 
> affect the ADEV. Similarly for frequency measurement which is the first 
> difference, phase offset does not affect the frequency estimation.
> 
>> If you have N phase samples, you get N-1 frequency samples and N-2
>> drift samples. The standard ADEV calculation is simply based on the
>> mean of those drift samples. (and you know Hadamard takes this one
>> step deeper).
>> 
>> If you look a the code at http://leapsecond.com/tools/adev_lib.c
>> you'll see I avoid the confusing issue of N-1, N, N+1 and simply
>> count the number of terms in the rms sum. Not only does that give the
>> correct result but IMHO it make it clear what is being averaged. The
>> code passes the official NBS ADEV sample suite, agrees with Bill's
>> Stable32, is used in John's TimeLab, and also Mark's Lady Heather.
> 
> The NIST 1000-point test-suite in NIST SP 1065 is recommended these days
> as a test sequence. That's what I used to test all my implementations.
> 
>> I've never quite understood the pedantic separation of "sample" and
>> "population" mean that statistic textbooks and academics love to
>> discuss. They clearly have never measured oscillators. In my
>> experience if you think there's an important difference between N and

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Re: [time-nuts] Line Voltage - USA

[Bob Camp]

Hi

> On Jan 4, 2017, at 3:42 AM, Hal Murray  wrote:
> 
>> Did the utility replace the damaged equipment?
> 
> A friend lived in a building when the city crew working on a transformer put 
> 440 on the line.  It blew out all the electronics in 12 condos - mostly TVs.  
> I think toasters and refrigerators were OK.  There wasn't any question that 
> the city was at fault.  I don't remember how much paperwork they had to go 
> through to get reimbursed.  It might get sticky for something like a time-nut 
> with a lot of used gear that may not be easy to replace at the original 
> price.  (Could be a good excuse to clean up and start over.)
> 
> How much trouble do hams have with their insurance companies?



In some cases quite a lot. They paid the claim and dropped us. The way
they did it, getting insurance again at a rational price ( < 5X what we had
been paying) was a major pain. We did find a rational company and have
been very happy with them for 40 years now. Each time the guys who 
dropped us call to get us to switch, I tell them the story ….

Bob


> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Line Voltage - USA

[Bob Camp]

HI


> On Jan 3, 2017, at 6:59 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> They sell a lot of 24 bit audio DAC’s into that sort of gear. Team them up
>> with some DSP and you get all sorts of interesting data. The “one number”
>> that counts is the fundamental ….
> 
> DAC?
> 


 Typo … sorry

Bob

> There is a big market for high resolution ADCs in that area - one in every 
> modern power meter.  (Maybe a pair so they can get voltage and current at the 
> same time.)
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Line Voltage - USA

[Bob Camp]

Hi

Measuring line voltage for “official” purposes straight up with a lab grade 
device that may
have a bandwidth of many KHz (or even 100’s of KHz) is generally not a good way 
to go. 
The line voltage is the value of the fundamental (50 or 60 Hz) sine wave. All 
the other nonsense
that accumulates is more likely load related than line related. If the power 
company brings
out the right stuff, it looks more like a spectrum analyzer inside than a 
normal voltmeter. They
sell a lot of 24 bit audio DAC’s into that sort of gear. Team them up with some 
DSP and you
get all sorts of interesting data. The “one number” that counts is the 
fundamental ….

Bob 


> On Jan 3, 2017, at 1:50 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 2 January 2017 at 05:15, Jeremy Nichols  wrote:
> 
>> Thank you for the detailed analysis, Bill. The voltage measurements I made
>> in my garage laboratory were duplicated by the utility with their meter,
>> which was connected at the service entrance.
> 
> 
> I have just been chatting to a friend who was a controller at two power
> stations in the UK - Darlington (coal) and Bradwell (nuclear). He tells me
> that the voltage is likely to be higher in the summer around 2-3 am in the
> morning. Now it might seem obvious that the load is smaller in summer than
> in the middle of winter, but this is NOT the reason the voltage rises more
> in summer. I must admit though, I could still not understand it, and he
> admits he could not explain it, but just tells me it is so. But a few
> things I did get, which are not all obvious - some are.
> 
> 1) The real power consumed by the users + losses must balance the power
> generated. That's pretty obvious.
> 
> 2) The reactive power (V*A) must also balance - perhaps less obvious.
> 
> 3) The voltage generated by a generator when it is not providing any load
> is controlled by the current in the field winding.
> 
> 4) Before connecting a generator to the grid it is necessary to ensure the
> voltage and phases are matched.
> 
> 5) Once the generator is on the grid, there's nothing the generator can do
> that has any practical effect on the voltage. Even with a nuclear power
> station, the output power it is a small fraction of the overall power being
> generated by the all the power stations, so one power station coming on/off
> line does not have any significant effect on the voltage of the grid.
> 
> 6) What the operator can do is
> 
> * Generator more power, by increasing the steam that drivers the generator.
> * Change the reactive power by changing the field current
> 
> 
> 7) As soon as the generator is connector, he would increase the steam to
> provide at least  5 MW at Bradwell (nuclear, 2 MW at Darlington (coal), as
> failing to do so risks the generator going unstable due to disturbances on
> the grid.  This could easily result in the generator becoming a motor,
> which is not good. So there's a minimum power a generator can practically
> provide - in his case 2 or 5 MW.
> 
> 8) If there were no uses on the grid, so nobody using any electricity, the
> capacitance of the cables would make the load capacitive.
> 
> 9) Users are generally inductive, so in practice the current lags the
> voltage, as the reactive power of users is greater than the the grid.
> 
> 10) The higher power usage in winter means that the power factor is further
> from 1.0.
> 
> I get the feeling that the voltage might go up more in summer as the
> generator are running closer to a point of instability, with small changes
> in load causes significantly more change in power factor than in the
> winter.
> 
> As I say, I never really seemed to get to the bottom of fully understanding
> this, but he assures me that voltages will be less stable at light load
> than at heavy load.
> 
> I guess if I do report a problem, I will get them to measure all 3 phases.
> That must increase the chances of at least one phase going outside
> specification. I am rugulary going over 250 V, but not 10% more which would
> be 253 V.
> 
> Dave
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Re: [time-nuts] Temperature (environmental) sensors

[Bob Camp]

Hi

There’s always the “cool factor” of higher resolution. Apparently it’s not 
enough
of a issue to make it a worthwhile market to serve.  

Based on what has been tossed around, it sounds like an Arduino with some 
bits plugged in is the low cost leader. 3D print up and enclosure and you have 
it all in a some large form factor.

Bob

> On Jan 3, 2017, at 12:54 PM, jimlux  wrote:
> 
> On 1/3/17 9:15 AM, Bob Camp wrote:
>> Hi
>> 
>> There is an ever increasing pool of good sensors to put into something like 
>> this.
>> (More so for temperature and pressure. Humidity still is a bit of an issue.)
>> There’s not a lot to interface between the sensor and a USB “chip”. It’s 
>> surprising
>> that there aren’t more cheap / high accuracy choices out there.
>> 
> 
> 
> the market probably isn't there for a cheap "pod" with an interface and high 
> accuracy..
> 
> The Lascar units (and similar $100-ish ones from others) meet most of the 
> existing need fairly well (e.g. monitoring the temperature of your freezer 
> for FDA regulatory compliance, monitoring the temp and humidity in your ESD 
> controlled space)..
> 
> The need for 0.1 degree C room temp measurement is, I think, fairly limited
> 
> 
> 
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