Re: [time-nuts] A Research Proposal

[Dave ZL3FJ]

I have here a pair of instruments that were part  of a system used  at one time 
 in a power station here in NZ  to control the time error in one  part of the 
national grid. It controlled the selected generators and provided a real time 
display of the time error between a reference standard and the 50 Hz mains 
frequency.  The system comprised an HP 5280A reversible counter  with two 
inputs, one from the  mains 50 Hz as generated and one from the reference 
standard. These two inputs were arranged to add  counts from one input and 
subtract counts from the other, such that the counter displayed zero while the 
generated 50 Hz was accurate. Offsets from 50Hz were displayed as positive or 
negative counts. The reference input was derived from an HP 105A quartz 
oscillator and the system included provision to manually  synch that to the 
national standard time standard on an as required basis. The output of the 
5280A counter drove an HP 6933B D/A converter, the bi-polar DC output of which 
was used (both magnitude and sign)  to control the governors on some of the 
hydro generators. Dual HP 5321B clocks were used to display TOD from both 
sources.
 The 6933B is complete but the 5280A counter has been partly disassembled.  The 
5321Bs never got this far-neither did the 105A- who knows, it might still be 
being used  as a reference!

DaveB, NZ

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Bill 
Hawkins
Sent: Monday, July 08, 2019 06:48
To: Bob via time-nuts
Subject: Re: [time-nuts] A Research Proposal

Group,

We've discussed this before, but maybe it needs to be said again.

Line frequency is not constant.   There is no master PLL.  Approximate 
frequency is maintained by a central power dispatching office in each of the 
four (?) regions tied together by their power distribution grid.  The 
dispatcher's goal is to create the same number of cycles of AC each day.  IIRC, 
power is bought and sold by the number of cycles generated.   As the daytime 
load increases, the generators slow down a bit.  Note that it is not possible 
for each generating station to control its frequency, as that would not be 
stable.  Instead, the dispatcher asks various plant operators to generate more 
or less steam (or water flow) in order to increase the frequency.  When the 
load drops at night, the generators speed up a bit, and steam has to be 
reduced. At the end of the day, so to speak, the number of cycles generated is 
very nearly equal to the number generated if the line frequency had been steady 
at 60 (or 50) cycles per second.  Synchronous clocks stay accurate although 
they may be off by a few seconds as dispatchers scramble to get enough steam to 
keep up.

So yes, you can get phase data within a region but you must compensate timing 
data as the frequency varies.

The regions are connected to each other for purposes of power sharing with DC 
transmission lines.  These use inverters to convert between AC and DC. The AC 
frequency is controlled by the grid that it is tied to.  Phase angle can be 
changed to change the amount and direction of the power transferred.

So no, you can't compare data from different regions, unless you want to know 
which way DC power is flowing.

I hope this was informative.

Bill Hawkins


On Thu, Jul 4, 2019, at 2:00 PM, Andy Backus wrote:
> Historically, and even today, the steady frequency of AC power has 
> been used for timekeeping.  So there may be interest here in the 
> following research proposal:
> 
> Within a given power distribution grid, several observers as widely 
> separated geographically as possible, time stamp the first two zero 
> crossings of the power line after each UTC second – over the course of
> 24 hours (86,400 pairs of data).
> 
> Popularly conceived, all the components of a power distribution grid 
> are phase locked – though, of course, power is taken in and out by 
> varying degrees of lead or lag.  Frequency is maintained by a constant 
> balancing act between load and generation.
> 
> Typical power distribution grids, however, are sized on a scale of 
> thousands of miles.  “Locking phase,” then, is problematic simply on 
> the basis of the limits of information transmission rate.  Even at c, 
> every 1000 miles takes 5 ms, which represents a third to a quarter of 
> the period of the AC power waveform.
> 
> Many interesting phenomena might result from that reality, which 
> suggests a certain constrained flexibility over large distances – 
> almost as if the system is like a large lake of viscous liquid.  When 
> there are local disturbances such as rapid load changes or sudden 
> generation adjustments, for example, it is quite possible harmonic 
> ripples could be propagated through the system.
> 
> Such effects could be observed by comparing phase data across 
> significant distances within a distribution grid.
> 
> Andy Backus
> Bellingham, WA
> USA
> 
> 
> From: tim

Re: [time-nuts] A Research Proposal

[Bill Hawkins]

Since the direction of power flow depends on the phase angle between the 
synchronous source and load, it seems to me that the difference between the 
average phase angle in one region and that in another (at the ends of a DC 
transmission line) will tell you which way power is flowing.  I didn't claim 
that the amount of power could be determined.  It can't.

Disclaimer - I'm a mechanical engineer who has made a career in the control of 
physical machines.  I've been interested in the power line stuff since a visit 
to the PenJerDel region distribution control center in the seventies.  Now that 
I'm 81, there's probably some holes in that knowledge.

Bill Hawkins

P.S.  I don't know who Bob is. That's the address pobox gave me when I said 
"Reply to List"

On Sun, Jul 7, 2019, at 5:00 PM, Hal Murray wrote:
> 
> > So no, you can't compare data from different regions, unless you want to 
> > know
> > which way DC power is flowing. 
> 
> How does knowing data about two regions tell me anything about how much power 
> is flowing and which direction?
> 
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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Re: [time-nuts] A Research Proposal

[Glen English VK1XX]

In Australia, we have a national grid. It's big.

National meaning all but a few isolated towns like Darwin, Perth. Perth 
might be connected via a 1800 km HVDC line in the future... which is a 
different story  DC interconnectors


So, I gather  someone  with their MASER in Adelaide could compare their 
MASER to the 50 Hz over some period, and provide the relative offset of 
the grid to others, so others  in australia also observing and averaging 
over some period , could get a useful frequency reference from their 
wall socket.


-which I gather is what people do , since i am new to this timing game.

That would have its limits depending on the ADEV of the mains . and the 
use of DC interconnectors.


-glen

On 8/07/2019 11:21 AM, Bob kb8tq wrote:

Hi

The whole “phase here vs phase there” thing was at the heart of the papers the
power guys started presenting back in the late 1980’s …. A




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[time-nuts] HP 5359A Time Synthesizer available

[Skip Withrow]

 Hello Time-Nuts,
I'm trying to lighten the load some and this HP instrument has risen
to the surface.  I acquired it with the intention of compensating the
1pps output of a GPS receiver for sawtooth correction.  The intention
was to take the serial output of the receiver and outputting a GPIB
command to the 5359A to move the 1pps appropriately.  I have never
gotten around to the programming part.

And it seems I already have tooo many projects in the queue.  So, I'm
offering it up to any time nut that is interested.

The unit appears to be functional. I have checked the front panel
controls and they appear to be working.  Unit has an internal
10811-60111 oscillator for the time base.

I'm offering it for $150 plus shipping.  Weight is about 30 pounds, it
is a 3U unit similar to the 5370.  Can be picked up in Denver if
desired.  If interested please contact me OFF LIST.

Thanks for the bandwidth,
Skip Withrow

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Re: [time-nuts] HP E1938A schematics.

[Glen English VK1XX]

Hi Rob

Thanks for the post. wow.  OK thanks for the notes.

No expense spared anywhere on the quality of those parts used.

mine are Rev Bs

 EEPROM. might need to read out that info while it is good.

Probably important parameters

what goes wrong with these babies ? or should I consult the list archives  ?

-glen


On 8/07/2019 3:50 AM, Rob040 . wrote:

Hi,

I've made some new schematics of the HP E1938 oscillator/controller module. I 
derived them from the HP schematics that I found on Brooks' site.
The aim was to have more clear versions for service/repair. They should reflect 
the situation as they left the factory, what isn't on the PCB isn't present in 
the drawings (not sure about the content of the oscillator 'puck'). It's the 
version with the 20P connector on the component side.




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Re: [time-nuts] A Research Proposal

[Bob kb8tq]

Hi

The whole “phase here vs phase there” thing was at the heart of the papers the 
power guys started presenting back in the late 1980’s …. At least back then the 
data
was between points a lot further spread out than both sides of a valley.

Bob

> On Jul 7, 2019, at 5:39 PM, jimlux  wrote:
> 
> On 7/7/19 11:48 AM, Bill Hawkins wrote:
>> Group,
>> We've discussed this before, but maybe it needs to be said again.
>> Line frequency is not constant.  
> 
> 
> I think the research is more about understanding the frequency and time 
> shifts across the network, referred to a more accurate and stable reference.  
> Not so much trying to use the grid as a time/frequency reference.
> 
> For instance, is the variation in phase across the San Fernando Valley 
> different in the afternoon when everyone turns on their air conditioner - 
> sure there's a "voltage at the user" change, but is there also a phase change.
> 
> 
> 
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Re: [time-nuts] A Research Proposal

[jimlux]

On 7/7/19 11:48 AM, Bill Hawkins wrote:

Group,

We've discussed this before, but maybe it needs to be said again.

Line frequency is not constant.  



I think the research is more about understanding the frequency and time 
shifts across the network, referred to a more accurate and stable 
reference.  Not so much trying to use the grid as a time/frequency 
reference.


For instance, is the variation in phase across the San Fernando Valley 
different in the afternoon when everyone turns on their air conditioner 
- sure there's a "voltage at the user" change, but is there also a phase 
change.




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Re: [time-nuts] A Research Proposal

[Hal Murray]

> So no, you can't compare data from different regions, unless you want to know
> which way DC power is flowing. 

How does knowing data about two regions tell me anything about how much power 
is flowing and which direction?



-- 
These are my opinions.  I hate spam.




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[time-nuts] Switching 1 pps signal

[Mark Sims]

When I first got my TAPR-TICC one of the first tests that I did with it was to 
put a coil of RG-58 in the freezer then measured the prop delay as it warmed 
up.  I posted a plot on the list.  I didn't have a temp sensor in the coil, 
though. 

https://www.febo.com/pipermail/time-nuts/2017-April/104923.html

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Re: [time-nuts] A Research Proposal

[Bill Hawkins]

Group,

We've discussed this before, but maybe it needs to be said again.

Line frequency is not constant.   There is no master PLL.  Approximate 
frequency is maintained by a central power dispatching office in each of the 
four (?) regions tied together by their power distribution grid.  The 
dispatcher's goal is to create the same number of cycles of AC each day.  IIRC, 
power is bought and sold by the number of cycles generated.   As the daytime 
load increases, the generators slow down a bit.  Note that it is not possible 
for each generating station to control its frequency, as that would not be 
stable.  Instead, the dispatcher asks various plant operators to generate more 
or less steam (or water flow) in order to increase the frequency.  When the 
load drops at night, the generators speed up a bit, and steam has to be 
reduced. At the end of the day, so to speak, the number of cycles generated is 
very nearly equal to the number generated if the line frequency had been steady 
at 60 (or 50) cycles per second.  Synchronous clocks stay accurate although 
they may be off by a few seconds as dispatchers scramble to get enough steam to 
keep up.

So yes, you can get phase data within a region but you must compensate timing 
data as the frequency varies.

The regions are connected to each other for purposes of power sharing with DC 
transmission lines.  These use inverters to convert between AC and DC. The AC 
frequency is controlled by the grid that it is tied to.  Phase angle can be 
changed to change the amount and direction of the power transferred.

So no, you can't compare data from different regions, unless you want to know 
which way DC power is flowing.

I hope this was informative.

Bill Hawkins


On Thu, Jul 4, 2019, at 2:00 PM, Andy Backus wrote:
> Historically, and even today, the steady frequency of AC power has been 
> used for timekeeping.  So there may be interest here in the following 
> research proposal:
> 
> Within a given power distribution grid, several observers as widely 
> separated geographically as possible, time stamp the first two zero 
> crossings of the power line after each UTC second – over the course of 
> 24 hours (86,400 pairs of data).
> 
> Popularly conceived, all the components of a power distribution grid 
> are phase locked – though, of course, power is taken in and out by 
> varying degrees of lead or lag.  Frequency is maintained by a constant 
> balancing act between load and generation.
> 
> Typical power distribution grids, however, are sized on a scale of 
> thousands of miles.  “Locking phase,” then, is problematic simply on 
> the basis of the limits of information transmission rate.  Even at c, 
> every 1000 miles takes 5 ms, which represents a third to a quarter of 
> the period of the AC power waveform.
> 
> Many interesting phenomena might result from that reality, which 
> suggests a certain constrained flexibility over large distances – 
> almost as if the system is like a large lake of viscous liquid.  When 
> there are local disturbances such as rapid load changes or sudden 
> generation adjustments, for example, it is quite possible harmonic 
> ripples could be propagated through the system.
> 
> Such effects could be observed by comparing phase data across 
> significant distances within a distribution grid.
> 
> Andy Backus
> Bellingham, WA
> USA
> 
> 
> From: time-nuts  on behalf of Thomas 
> D. Erb 
> Sent: Thursday, July 4, 2019 5:23 AM
> To: time-nuts@lists.febo.com
> Subject: Re: [time-nuts] 60 Hz frequency and phase measurement
> 
snip
> I had a recent tour of a power station - the operators had no idea the 
> output was synchronized to a time standard - they just synchronize with 
> the local grid.

> 
> Thomas D. Erb
> p:508-359-4396
> f:508-359-4482
> a:97 West Street, Medfield, MA 02052 USA
> e: t...@electrictime.com
> w:www.electrictime.com
> Tower & Street Clocks Since 1928
> 

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Re: [time-nuts] Advantages of GNSS ???

[Achim Gratz]

Leo Bodnar writes:
> Correction on all Ublox receivers including F9P is done at navigation
> rate which can be set as high as 20Hz.

If you are thinking of the sawtooth correction, then I think you'll find
that this is only available for the full second.  There is some mumbling
in the manual that the timing firmware would really like you to only
calculate one solution per second for best performance.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

SD adaptation for Waldorf Blofeld V1.15B11:
http://Synth.Stromeko.net/Downloads.html#WaldorfSDada

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Re: [time-nuts] Switching 1 pps signal

[Bob kb8tq]

Hi

As far as the coax goes, termination is a good idea. As far as the signal goes 
… maybe not so much ….

Using 5V logic as an example:

If you build up a driver that has a 50 ohm source impedance, you have a (so 
far) do-able project. The 
output delivered into a light load could be the same as the driving voltage. 
Simply put, a 5V driver will
deliver a 5V signal. 

If the driver is built just to drive a 50 ohm load, you can still get 5V into 
the load off of a 5V driver. The
output impedance will very much *not* be 50 ohms in this case. 

The textbook case is to have both ends of the cable properly terminated. You 
now have a 50 ohm driver
and a 50 ohm load. Your 5V signal at the driver end is a 2.5V signal at the 
load. If you are after 5V 
at the load, you need a 10V driver. 

Logic gets picky about levels. If it’s 5V logic, it may or may not be very 
happy with a 2.5V “logic high” 
signal. The edge rate will (probably) max out around 1.25V which again may or 
may not be what you
are after. 

The next issue is that with a 10V drive, an un-terminated device gets 10V. 
There is a lot of gear out 
there that is in the “damage” range at this sort of voltage. Indeed, you can 
get into these issues on 
gear that was new back in the 1970’s.  Indeed there is gear that 5V will nuke ….

So what to do …..

The most practical approach is to source terminate only. As mentioned in other 
posts, this may not
be ideal for isolation. 

Another practical solution is to simply treat these as logic signals and use 
gates to switch them. If
your sources are things like GPS modules, Cs standards, or GPSDO’s, that is 
usually an acceptable 
approach. If you are running a Hydrogen Maser …. maybe not. 

The “why” depends a bit on how much the “couple of picoseconds” wobble in the 
high speed gate 
bothers you. A lot of devices are noisy enough that their noise will be way 
more than that . Indeed 
logic families vary in terms of jitter so you need to be a bit careful about 
what you use for what. 

Bob

> On Jul 7, 2019, at 10:59 AM, Taka Kamiya via time-nuts 
>  wrote:
> 
> Being a Ham and experienced 10base-2, I'm rather careful with termination but 
> thanks for the reminder.  I've decided to use coax relay 18GHz that I have a 
> lot of, and purchased cheaply.  That way, there is no question.  
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> 
> 
>On Sunday, July 7, 2019, 4:01:32 AM EDT, Glen English VK1XX 
>  wrote:  
> 
> In that case, my suggestion is think of them all as transmission lines 
> in coax. terminate as needed.
> 
> Others here will also have points I have missed I am sure, or 
> alternative equally valid suggestions.
> 
> beign critical (maybe I am being over critical) :
> 
> watch out also for reflections from unterminated (open ) relay contacts, 
> the 2x pulse you might get back at the driver might cause harm or 
> trouble on the supply rail.
> 
> IE so source terminate ideally, even if it costs you a little swing or 
> at least a little series R like 10 ohms  source R to mop up reflections 
> back on the source... if its swinging 2V with source term = 10 ohms into 
> 51 ohms, that wont hurt too much.
> 
> rather than just totem pole strong CMOS driver , consider LVPECL style 
> driving, also.
> 
> IE it depends what drivers and receivers you choose simple would be 
> all 1.8V CMOS I guess, most stronger buffers will drive 50 ohms and 1.8V
> 
> if you plan on multiple drop, then you'll need to consider where you 
> place the termination...  which is why differential rocks over single 
> ended because the swing can drop before the trouble develops with double 
> termination.  of course if you AC couple into single ended setups that 
> can work but messy.
> 
> 
> glen
> 
> 
> On 7/07/2019 2:07 PM, Taka Kamiya via time-nuts wrote:
>> I should have mentioned this clearly earlier, but all converting and 
>> switching, then measuring happens in ONE 2U rack case.  Length of each cable 
>> is minimal.  I thought mention of TICC would make it sort of clear but it 
>> didn't.
>> I have LOTS of coax relays.  I'll use them.  It's a gross overkill but I've 
>> seen 80s HP equipment have overly generous parts selections, too.  It's hard 
>> to explain EXACTLY as the contraption isn't built yet.  That made it 
>> necessary to use generic terms.  I apologize for causing confusion.
>> 
>> ---
>> (Mr.) Taka Kamiya
>> KB4EMF / ex JF2DKG
>>   
>> 
>>   On Sunday, July 7, 2019, 12:00:52 AM EDT, Glen English VK1XX 
>>  wrote:
>>   
>>   Hal, Good point.
>> 
>> and I have never seen a spec for phase stability for Cat-7 cable !
>> 
>> for RG58, OR OTHER polyethylene, might be up to 150ppm /deg C. maybe as
>> good as 10 ppm/deg C for some LMR.
>> 
>> With 1000 feet of cable might be an issue for fine stuff. a few nano
>> seconds each way over temperature might not matter for his project...
>> 
>> I forget it is not a microwave  RF  VNA appl

Re: [time-nuts] Switching 1 pps signal

[jimlux]

On 7/6/19 8:34 PM, Glen English VK1XX wrote:

Hal, Good point.

and I have never seen a spec for phase stability for Cat-7 cable !

for RG58, OR OTHER polyethylene, might be up to 150ppm /deg C. maybe as 
good as 10 ppm/deg C for some LMR.


With 1000 feet of cable might be an issue for fine stuff. a few nano 
seconds each way over temperature might not matter for his project...


I forget it is not a microwave  RF  VNA application. Easy to resolve 
anyway with a difference balance term somewhere.


g


The propagation velocity variation is from:
1) change in the density of the dielectric with temperature, which 
changes the epsilon
2) change in the dimensions of the transmission line, which changes the 
"per unit" inductance and capacitance, changing the propagation constant 
(proportional to sqrt(LC))


If you need to deal with the propagation velocity variation, then what 
you do is look for the reflection coming back, time that relative to the 
sending, and use that to correct the timing of the far end.


Of course, an edge has all frequencies, and the propagation constant is 
not the same for all frequencies (some dispersion), so that brings in 
another set of problems.


People who do stuff like coherent combining of large microwave antennas 
for interferometry do stuff like run the coax/fiber in a temperature 
controlled conduit. (and even then, there's "post processing")






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Re: [time-nuts] Switching 1 pps signal

[Taka Kamiya via time-nuts]

Being a Ham and experienced 10base-2, I'm rather careful with termination but 
thanks for the reminder.  I've decided to use coax relay 18GHz that I have a 
lot of, and purchased cheaply.  That way, there is no question.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, July 7, 2019, 4:01:32 AM EDT, Glen English VK1XX 
 wrote:  
 
 In that case, my suggestion is think of them all as transmission lines 
in coax. terminate as needed.

Others here will also have points I have missed I am sure, or 
alternative equally valid suggestions.

beign critical (maybe I am being over critical) :

watch out also for reflections from unterminated (open ) relay contacts, 
the 2x pulse you might get back at the driver might cause harm or 
trouble on the supply rail.

IE so source terminate ideally, even if it costs you a little swing or 
at least a little series R like 10 ohms  source R to mop up reflections 
back on the source... if its swinging 2V with source term = 10 ohms into 
51 ohms, that wont hurt too much.

rather than just totem pole strong CMOS driver , consider LVPECL style 
driving, also.

IE it depends what drivers and receivers you choose simple would be 
all 1.8V CMOS I guess, most stronger buffers will drive 50 ohms and 1.8V

if you plan on multiple drop, then you'll need to consider where you 
place the termination...  which is why differential rocks over single 
ended because the swing can drop before the trouble develops with double 
termination.  of course if you AC couple into single ended setups that 
can work but messy.


glen


On 7/07/2019 2:07 PM, Taka Kamiya via time-nuts wrote:
> I should have mentioned this clearly earlier, but all converting and 
> switching, then measuring happens in ONE 2U rack case.  Length of each cable 
> is minimal.  I thought mention of TICC would make it sort of clear but it 
> didn't.
> I have LOTS of coax relays.  I'll use them.  It's a gross overkill but I've 
> seen 80s HP equipment have overly generous parts selections, too.  It's hard 
> to explain EXACTLY as the contraption isn't built yet.  That made it 
> necessary to use generic terms.  I apologize for causing confusion.
>
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>  
>
>      On Sunday, July 7, 2019, 12:00:52 AM EDT, Glen English VK1XX 
> wrote:
>  
>  Hal, Good point.
>
> and I have never seen a spec for phase stability for Cat-7 cable !
>
> for RG58, OR OTHER polyethylene, might be up to 150ppm /deg C. maybe as
> good as 10 ppm/deg C for some LMR.
>
> With 1000 feet of cable might be an issue for fine stuff. a few nano
> seconds each way over temperature might not matter for his project...
>
> I forget it is not a microwave  RF  VNA application. Easy to resolve
> anyway with a difference balance term somewhere.
>
> g
>



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Re: [time-nuts] Advantages of GNSS ???

[Bob kb8tq]

Hi

They go absolutely crazy updating nav….. but they only come up with the timing 
correction once a second.

From the latest version of the F9T Manual UBX-19005590 - R02  on page 43: 
The recommended configuration when using the UBX-TIM-TP message is to set both 
the measurement rate (CFG-RATE-MEAS) and the time pulse frequency (CFG-TP-*) to 
1Hz.

Since the rate of UBX-TIM-TP is bound to 1 Hz, more than one UBX-TIM-TP message 
can appear between two pulses if the time pulse frequency is set lower than 1 
Hz. In this case all UBX-TIM-TP messages in between a time pulse T1 and T2 
belong to T2 and the last UBX- TIM-TP before T2 reports the most accurate 
quantization error. In general, if the time pulse rate is not configured to 1 
Hz, there will not be a single UBX-TIM-TP message for each time pulse. 

Sorry if the quote comes through a bit garbled. Sometimes this cut and paste 
stuff does not quite do the trick. 
Indeed it’s not 100% clear what they are doing from the docs. They say this and 
that here and there. The 
bottom line is still that you can only trust the sawtooth offset data to be 
correct at the one second point. 

Bob

> On Jul 7, 2019, at 8:42 AM, Leo Bodnar  wrote:
> 
> Correction on all Ublox receivers including F9P is done at navigation rate 
> which can be set as high as 20Hz.
> Leo
> 
>> From: Bob kb8tq 
>> Frequency of any GNSS output on the F9P is limited by the accuracy of the 
>> time pulse. 
>> Correction is only done once a second.
> 
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Re: [time-nuts] Advantages of GNSS ???

[Leo Bodnar]

Correction on all Ublox receivers including F9P is done at navigation rate 
which can be set as high as 20Hz.
Leo

> From: Bob kb8tq 
> Frequency of any GNSS output on the F9P is limited by the accuracy of the 
> time pulse. 
> Correction is only done once a second.

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Re: [time-nuts] FEI 405B oscillators

[ewkehren via time-nuts]

Gerhard, does not sound right, Tom did an extensive evaluation, steps in 6.6 
E-15 at 15 MHz. Our best GPSDO.Am out of  town back Tuesday have extensive info 
on my PC need to get off listBertSent from my Galaxy Tab® A
 Original message From: Gerhard Hoffmann  Date: 
7/6/19  11:58 PM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: [time-nuts] FEI 405B 
oscillators Hi,I have one of these FEI405 oscillators from this list auction 4 
years ago.While it dives nicely down deep into E-13 land over some seconds, it 
only delivers -2.5 dBm output powerand has a lot of phase noise and spurs far 
out. That does not look healthy.Is there a real data sheet out there in the 
wild, or has someone even re-engineered this thing?If you google for it, you 
get links to Fender guitar bags, fertilizers and electron microscopes,but 
nothing on oscillators apart of the time nuts thread from 4 years ago.If the 
data sheet really says -2 dBm, then I could get rid of the spurii and life 
would be OK.Yes, I have found the Frequency Electronics web site, but it seems 
they deny 
parenthood.Gerhard___time-nuts 
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Re: [time-nuts] Switching 1 pps signal

[Anders Wallin]

Hi Taka,
I made an 1:8 multiplexer with TE HF3 relays. They are specified up to 3
GHz, but the 'tree'-design has log2(8) = 3 levels - i.e. the signal always
passes through three relays.
in practice I got around 1 GHz -3dB bandwidth, which I think is OK for 1PPS
http://www.anderswallin.net/2018/05/mux-in-a-box/
I should measure and document the 1PPS rise-time/shape before and after the
multpliexer..

If someone knows of a significantly better relay than the TE HF3 at similar
price then that would be an improvement..

Anders

On Sun, Jul 7, 2019 at 12:01 AM Taka Kamiya via time-nuts <
time-nuts@lists.febo.com> wrote:

> I am trying to come up with a viable design to encase TICC along with
> 10MHz -> 1 pps converter.  My plan is to share the input connector and
> switch in/out the converter.
>
> 1 pps, although technically a 1Hz signal, rise time and duration is
> awfully short on some sources.  I'm sure constituent signal will go way
> into RF range.  I am not capable of calculating this.  But, that means I
> really have to treat it as an RF signal, correct?  Otherwise, slower rise
> will cause error as it will cross the threshold later than initiation of
> the pulse.  Question is, how careful do I need to be?
> My plan is to use two 18GHz microwave relay per channel to bypass/place-in
> the converter.  I know this would be OK but am I over-doing this?  I also
> have a miniature relay in DIP size but I'm afraid it may not be
> sufficient.  There is not a frequency spec, and consistency may be an issue.
> Advise, please?
>
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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Re: [time-nuts] Multiple OCXO (topic changed from E1938A )

[Glen English VK1XX]

Hi  Bob, and Achim . thanks for the comments. I've change the subject 
line to fit more in line we the morphed discussion.


Good discussion, and like Bob said, there will be lots of common mode on 
the GPSs. The diurnal GPS derived clock errors due to the ionosphere are 
well described .   Bob thats a good point about picking and choosing, 
and long term effects.


My initial obs on two devices, tell me there IS  significant 
non-correlated noise between two of them, but this is on low cost GPS  
and also I have not yet established how much noise is purely my edge 
point sampling errors and nothing to do with the actual device, and the 
two in question have different views of the sky


Acbom, you have clearly thought about this. As for the IDELAYS etc, 
IDELAYS yes have been used for this sort of thing since the mid 90s.  
Enough of them and enough inputs and some known waveform to compensate 
against, and some differential means,  should be enough to mitigate the 
temperature/process effects. If rising and falling edges are worked, 
delay will affect both and compensate. While 1pps source might usually 
be only accurate on one edge, nothing an external ECL / GaAs flip flop 
won't fix to provide 1/2 pps.


One can also use PCB delay...150ps per inch... being careful of FR4 
weave , zig zags etc.although once the rise time of the signal gets 
amongst the delay we want, thats uncertainty.


 ***
Assuming we end up with a single, nice clean compensated and as good as 
possible timebase (from 1pps etc) (sounds like your territory, Bob), and
With multiple OCXO ( ALL being simultaneously inter-dependently 
disclipined ) , there may be the opportunity to try different parameters 
(or even algorithms) on the different OCXOs and pick the one with the 
minimum squared error (or something like that) . What might kill that is 
that the OCXOs vary quite alot even on the same model.


The goal of this is

a) to learn something- precision instrumentation is hard.

b) have a 1e-13 accurate long term (weeks on) frequency reference

c) have short term 1000 second stability <= 1e-12



glen




On 7/07/2019 6:56 PM, Achim Gratz wrote:

Glen English VK1XX writes:




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Re: [time-nuts] A Research Proposal

[Hal Murray]

> Within a given power distribution grid, several observers as widely separated
> geographically as possible, time stamp the first two zero crossings of the
> power line after each UTC second –over the course of 24 hours (86,400 pairs
> of data). 

Life is more complicated than that.  There is a race condition when a zero 
crossing happens close to the second tick.  Did it happen before or after?

You might be able to dance around that by taking 3 samples if the first one is 
closer than X ms to the second tick and sort it out with post processing.  I 
think your data stations will need to be located close enough together.

You probably also have an issue with 3 phase.  Are you measuring stations all 
on the same phase?  There is another factor of 2 from flipping the output leads 
of the transformer or plugging into the other side of the 110/220.

-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] E1938A source code/ firmware

[Achim Gratz]

Glen English VK1XX writes:
> My intention is to use the average of multiple stationary mode GPS
> 1PPS signals to drive a single OCXO, the idea to be a better 1pps
> estimate. I'll upsample the inputs to get the control sample rate up.

I'd expect a lot of correlation among multiple GPS receivers, especially
when they're fed from the same antenna and are otherwise sharing the
same environment.  Averaging will only deal with the non-correlated
errors in the signal.

> Eventually I want to explore the use multiple OCXOs, but not until I
> think of a good way to take an average of multiple OCXOs, or, even if
> that is a useful idea.

I think you'll have trouble isolating these well enough to not (at least
occasionally) injection lock on each other.

> FPGA based,  I'll  put the OCXO drive and the 1ppS to the FPGA
> differentially into maybe  8 FPGA inputs (that is each signal into 8
> different FPGA pin pairs) , and use IDELAY blocks to delay the 8
> different inputs to provide more edge resolution for each signal.

There are a few recent papers on that topic and the IDELAY blocks are
indeed used in some of these.  Getting them to track over voltage and
temperature is apparently a problem, so different methods of
implementing the TDC seem to be more useful depending on how far down
you want to push the resolution.

> The IDELAY blocks can be dynamic but I'll probably use then
> fixed. output of the FPGA can be sigma-delta converter, which can
> provide almost arbritary number of bits. LVDS output of the 1 bit FPGA
> converter signal will go to an outboard LVDS buffer with its own power
> supply so bumps on FPGA  VCCIO dont affect the output.

Getting the residual noise down on that signal will still be a
challenge, so you might want to (optionally) consider a proper DAC there
depending on how good an OCXO you intend to use.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Factory and User Sound Singles for Waldorf Blofeld:
http://Synth.Stromeko.net/Downloads.html#WaldorfSounds

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Re: [time-nuts] 60Khz received on Wide-band WebSDR

[Magnus Danielson]

Hi,

On 2019-07-06 20:39, Poul-Henning Kamp wrote:
> 
> In message 
> ,
>  "D. Resor" writes:
>
>>> From another list I was directed to this link for those who do not have a
>> shortwave radio.
>>
>> http://websdr.ewi.utwente.nl:8901/
>>
>> I entered the frequency of 60Khz and am curious to know if this the WWVB
>> transmission I am hearing or something else?
> No, that is the UK Rugby transmitter.
>
> For SDR transmitters all over the world, mainly John's KiwiSDR, visit 
> http://sdr.hu
>
The MSF is not transmitted from Rugby anymore, it's transmitted from
Anthorn.

Cheers,
Magnus



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Re: [time-nuts] 60Khz received on Wide-band WebSDR

[Magnus Danielson]

Hi,

On 2019-07-06 20:39, Poul-Henning Kamp wrote:
> 
> In message 
> ,
>  "D. Resor" writes:
>
>> >From another list I was directed to this link for those who do not have a
>> shortwave radio.
>>
>> http://websdr.ewi.utwente.nl:8901/
>>
>> I entered the frequency of 60Khz and am curious to know if this the WWVB
>> transmission I am hearing or something else?
> No, that is the UK Rugby transmitter.
>
> For SDR transmitters all over the world, mainly John's KiwiSDR, visit 
> http://sdr.hu
>
The MSF is not transmitted from Rugby anymore, it's transmitted from
Anthorn.

Cheers,
Magnus


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Re: [time-nuts] Switching 1 pps signal

[Glen English VK1XX]

In that case, my suggestion is think of them all as transmission lines 
in coax. terminate as needed.


Others here will also have points I have missed I am sure, or 
alternative equally valid suggestions.


beign critical (maybe I am being over critical) :

watch out also for reflections from unterminated (open ) relay contacts, 
the 2x pulse you might get back at the driver might cause harm or 
trouble on the supply rail.


IE so source terminate ideally, even if it costs you a little swing or 
at least a little series R like 10 ohms  source R to mop up reflections 
back on the source... if its swinging 2V with source term = 10 ohms into 
51 ohms, that wont hurt too much.


rather than just totem pole strong CMOS driver , consider LVPECL style 
driving, also.


IE it depends what drivers and receivers you choose simple would be 
all 1.8V CMOS I guess, most stronger buffers will drive 50 ohms and 1.8V


if you plan on multiple drop, then you'll need to consider where you 
place the termination...  which is why differential rocks over single 
ended because the swing can drop before the trouble develops with double 
termination.  of course if you AC couple into single ended setups that 
can work but messy.



glen


On 7/07/2019 2:07 PM, Taka Kamiya via time-nuts wrote:

I should have mentioned this clearly earlier, but all converting and switching, 
then measuring happens in ONE 2U rack case.  Length of each cable is minimal.  
I thought mention of TICC would make it sort of clear but it didn't.
I have LOTS of coax relays.  I'll use them.  It's a gross overkill but I've 
seen 80s HP equipment have overly generous parts selections, too.  It's hard to 
explain EXACTLY as the contraption isn't built yet.  That made it necessary to 
use generic terms.  I apologize for causing confusion.

---
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
  


 On Sunday, July 7, 2019, 12:00:52 AM EDT, Glen English VK1XX 
 wrote:
  
  Hal, Good point.


and I have never seen a spec for phase stability for Cat-7 cable !

for RG58, OR OTHER polyethylene, might be up to 150ppm /deg C. maybe as
good as 10 ppm/deg C for some LMR.

With 1000 feet of cable might be an issue for fine stuff. a few nano
seconds each way over temperature might not matter for his project...

I forget it is not a microwave  RF  VNA application. Easy to resolve
anyway with a difference balance term somewhere.

g





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