Re: [time-nuts] Weird Stuff WareHouse shutting down

[Hal Murray]

drkir...@kirkbymicrowave.co.uk said:
> I think people learn more with old test equipment.  I know someone who has a
> 1 GHz LeCroy scope,  as well as a high end Agilent, but can't seem to
> measure the simplest of signals, that I could easily measure with a 50 year
> old scope. 

With modern scopes, you just push the button.  1/2 :), but the one on my 
Rigol scope is labeled "Auto".


Many years ago, my boss used to use a scope when interviewing technicians: 
scramble the knobs, then watch how they sort things out.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Glenn Little WB4UIV]

The USB stuff has no front end and stability and calibration is highly 
questionable..
How can you discriminate between mixes within the USB device and the 
signal of interest?

I will take my 141T or my 8566 over USB every time.
Rather lug a little weight around and know what I am seeing on the 
display is what is really out there.
There is a reason that usable SAs have weight to them and USB devices do 
not.


Glenn


On 4/8/2018 6:58 PM, Andy ZL3AG via time-nuts wrote:

On 9/04/2018, at 3:52 AM, jimlux wrote:


Test equipment tends to be aged - Unless you have a particular need for a HP 
600 series microwave signal generator, there are probably better sources 
available much cheaper that use more modern components. In this day and age, I 
don't think people should suffer through 141T spectrum analyzers or even a 
8568- Spend your money an a nice USB unit instead.


Blasphemy!


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--
---
Glenn LittleARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

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Re: [time-nuts] ADEV dead time w/ HP 53131A & TimeLab

[Bob kb8tq]

Hi

The basic fact is that oscillators drift on *all* time scales. How much they 
drift 
depends on the type of oscillator. A free running VCO based on a PCB resonator
will drift differently than a bare crystal oscillator. An OCXO will have 
different drift
characteristics than a bare oscillator. 

A 53131 by its self is not capable of measuring the ADEV of a crystal 
oscillator over
short time periods. The counter’s ability scales by the gate time so eventually 
if the
gate time is long enough, it will catch up. That might be beyond 1,000 seconds 
for a
good OCXO. By that point, your dead time concerns are not as significant. 

There are a number of methods out there to get higher resolution than a bare 
counter
will provide. The NIST Time and Frequency archives have quite a bit buried in 
them. 
That includes information that digs into your dead time concerns. 

One alternative to the 53131 is a TimePod from Symmetricom. A somewhat less 
expensive approach is a DMTD setup. Both require a “better than” device to 
compare
your oscillator under test to. Unfortunately that’s a drawback to pretty much 
all ways
to do this. If your reference is more noisy than your DUT, you will just see 
the reference. 

Bob

> On Apr 8, 2018, at 9:29 PM, David Burnett  wrote:
> 
> Hi time-nuts,
> 
> I'm doing oscillator-related research for my PhD and found this list
> recently. It's been a great resource in trying to refine my freq
> measurement setup and in starting to understand what's really going on
> inside my lab equipment.
> 
> I've been trawling the archives and have a question about measuring ADEV
> accurately with the Agilent 53131A frequency counter I have on hand. From
> the comments on this list and elsewhere, and the fact that TimeLab will
> talk to my 53131A directly, I have the impression one can use the 53131A
> for period measurements with which to calculate ADEV. But from GPIB command
> sniffing it looks like there's a lot of dead time between measurements:
> -- In period or freq mode* measurements take an extra ~130ms longer than
> gate time to return (but this seems to produce the correct measurements for
> TimeLab);
> -- in time interval mode they take about ~20ms;
> -- in totalize mode they take about 5ms, in keeping with "200 measurements
> per second" advertised in the brochure, but of course this is a simple
> counter and one loses the resolution of a reciprocal counter or anything
> smarter added in.
> 
> Is it just generally assumed everyone is making period measurements on time
> scales long enough that any instrument dead time is ignorable? Or is
> TimeLab and everyone else silently applying the correction factor as
> described by the Barnes & Allan NIST paper (NIST technical note 1318)? Or
> is there a configuration mode I'm missing that prints measurements with
> more regularly? TimeLab's GPIB commands seem to be limited to "get current
> measurement" so I might not have the box set up right to start with.
> 
> My research concerns oscillator drift on time scales of ~1ms to ~10s, so
> I'm guessing the 53131A with its 5-130ms of dead time isn't suitable for
> what I'm trying to measure. But I'd still like to know how folks are
> getting around this dead time issue with the 53131A for their measurements
> in hopes it'll shed light on how I can do the same without needing to pick
> up more gear and the inevitable shipping delay that will entail. I suspect
> someone will recommend that I get a time-stamping/continuous measurement
> box, which is probably the best solution. But I'm hoping there's a way
> around that in the short term so I can make these measurements sooner.
> 
> 73,
> Dave
> 
> * Others on this list have warned about using this mode because the machine
> does a lot of averaging but it seems like TimeLab needs the box to be in
> this mode regardless. I'm still looking for the part in the manual where
> HP/Agilent/Keysight owns up to this and describe how it changes the
> measurement.
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Re: [time-nuts] Cheap jitter measurements

[Tisha Hayes]

" I appreciate that the clock-blessed may have doubts about the truth of his
sources. But the fact is, you need a larger sample size to better estimate
error. The man who is happy in his ignorance has not considered that
calibrated doubt can be more satisfying than unjustified certainty."

Just like being trapped in a speeding car with the in-laws; Time is
relative. And even if you are in a localized frame of reference it never
goes faster.

*Ms. Tisha Hayes*


On Sun, Apr 8, 2018 at 9:18 PM, Adrian Godwin  wrote:

> That may be an article of faith for those who haven't experienced the
> delights of time-nuttery, but to be fair, the man with n<2 clocks doesn't
> know what time it is either. Even if n=1, he only believes he knows what
> time it is.
>
> I appreciate that the clock-blessed may have doubts about the truth of his
> sources. But the fact is, you need a larger sample size to better estimate
> error. The man who is happy in his ignorance has not considered that
> calibrated doubt can be more satisfying than unjustified certainty.
>
>
> On Sun, Apr 8, 2018 at 11:01 PM, Dana Whitlow 
> wrote:
>
> > Pity the poor man who has (n>1) clocks, for he knows not what time it is.
> >
> > Dana
> >
> >
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> ___
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> mailman/listinfo/time-nuts
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[time-nuts] ADEV dead time w/ HP 53131A & TimeLab

[David Burnett]

Hi time-nuts,

I'm doing oscillator-related research for my PhD and found this list
recently. It's been a great resource in trying to refine my freq
measurement setup and in starting to understand what's really going on
inside my lab equipment.

I've been trawling the archives and have a question about measuring ADEV
accurately with the Agilent 53131A frequency counter I have on hand. From
the comments on this list and elsewhere, and the fact that TimeLab will
talk to my 53131A directly, I have the impression one can use the 53131A
for period measurements with which to calculate ADEV. But from GPIB command
sniffing it looks like there's a lot of dead time between measurements:
-- In period or freq mode* measurements take an extra ~130ms longer than
gate time to return (but this seems to produce the correct measurements for
TimeLab);
-- in time interval mode they take about ~20ms;
-- in totalize mode they take about 5ms, in keeping with "200 measurements
per second" advertised in the brochure, but of course this is a simple
counter and one loses the resolution of a reciprocal counter or anything
smarter added in.

Is it just generally assumed everyone is making period measurements on time
scales long enough that any instrument dead time is ignorable? Or is
TimeLab and everyone else silently applying the correction factor as
described by the Barnes & Allan NIST paper (NIST technical note 1318)? Or
is there a configuration mode I'm missing that prints measurements with
more regularly? TimeLab's GPIB commands seem to be limited to "get current
measurement" so I might not have the box set up right to start with.

My research concerns oscillator drift on time scales of ~1ms to ~10s, so
I'm guessing the 53131A with its 5-130ms of dead time isn't suitable for
what I'm trying to measure. But I'd still like to know how folks are
getting around this dead time issue with the 53131A for their measurements
in hopes it'll shed light on how I can do the same without needing to pick
up more gear and the inevitable shipping delay that will entail. I suspect
someone will recommend that I get a time-stamping/continuous measurement
box, which is probably the best solution. But I'm hoping there's a way
around that in the short term so I can make these measurements sooner.

73,
Dave

* Others on this list have warned about using this mode because the machine
does a lot of averaging but it seems like TimeLab needs the box to be in
this mode regardless. I'm still looking for the part in the manual where
HP/Agilent/Keysight owns up to this and describe how it changes the
measurement.
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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Dr. David Kirkby]

On 8 Apr 2018 16:56, "jimlux"  wrote:
>

> Test equipment tends to be aged - Unless you have a particular need for a
HP 600 series microwave signal generator, there are probably better sources
available much cheaper that use more modern components. In this day and
age, I don't think people should suffer through 141T spectrum analyzers or
even a 8568- Spend your money an a nice USB unit instead.

I think people learn more with old test equipment.  I know someone who has
a 1 GHz LeCroy scope,  as well as a high end Agilent, but can't seem to
measure the simplest of signals, that I could easily measure with a 50 year
old scope.

I heard about someone who could not use an analogue multimeter as it could
not measure negative voltages.

The above said,  I don't entirely disagree with you either.

Dave, G8WRB.
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Re: [time-nuts] Cheap jitter measurements

[Adrian Godwin]

That may be an article of faith for those who haven't experienced the
delights of time-nuttery, but to be fair, the man with n<2 clocks doesn't
know what time it is either. Even if n=1, he only believes he knows what
time it is.

I appreciate that the clock-blessed may have doubts about the truth of his
sources. But the fact is, you need a larger sample size to better estimate
error. The man who is happy in his ignorance has not considered that
calibrated doubt can be more satisfying than unjustified certainty.


On Sun, Apr 8, 2018 at 11:01 PM, Dana Whitlow  wrote:

> Pity the poor man who has (n>1) clocks, for he knows not what time it is.
>
> Dana
>
>
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] TS2100 OCXO Conversion: Command exploration

[Bruce Lane]

And, as of today, I still can't get it to lock. :-P

I think I'm going to have to conclude, reluctantly, that the full-size
OCXO's are simply not compatible with this unit. It strikes me as
possible there may be other hardware changes needed to run such. It's
just impossible to tell for certain without some kind of schematic.

So -- Reverse conversion, here we go. Looks like I'll just have to
settle for a square wave until I can find a couple of MTI 240's

Thanks to all who rendered assistance.


On 07-Apr-18 16:08, Esa Heikkinen wrote:

> Hi!
> 
> I have TS2100 which I modified from TCXO to OCXO. I have the 'offical'
> MTI OCXO, which I bought from someone on this board. I have also
> replaced the GPS unit to the HEOL Design model, which was required to
> get correct time at all. It's also much more accurate than the original
> Trimble.
> 
>> Now, with all this said: I'm still waiting for a 'Lock' indicator on
>> the front. It's tracking, and the D/A value certainly has changed from
>> what I had it at last night, but I'm still not getting a lock. Here are
>> my current numbers:
> 
> If I turn off the unit and the OCXO is totally cooled down then it might
> need even 2-3 hours before getting the LOCK indicator on again! So
> please be patient.
> 
> According to my measurements the LOCK indicator will turn on when the
> PPS has gone within 1  microsecond of UTC. But it's not fully locked
> even at this point! With HEOL Design GPS unit it will end up within 50
> nanoseconds of UTC, but that requires even more time.
> 
> If you have trouble with locking you should compare the PPS with
> oscilloscope with some other receiver (for example Thunderbolt) or maybe
> you could 'steal' the PPS from the internal GPS and compare it with
> output. You should see it trying to reach the correct PPS and if it
> passes it at startup, it should change the direction and finally settle
> near the PPS input. In case of trouble you could also try with different
> A/D values manually and see what they do.
> 
>> root timing utils tfp 0 -- returned 0x00f2
> 
> That cannot be correct: Value is too low, near zero volts perhaps and it
> might be clipped. Looks like it has drived itself to the lower limit
> without getting correct feedback. This is a clear sign that clock
> steering is not working at all.
> 
> From my unit:
> 1 ? tim
> 2 ? utils
> 3 ? tfp 0
> 0xb676
> 
>> root timing utils tfp 6 -- returned KM = 0.9994965
> 
> 4 ? tfp 6
> KM = 0.9994965
> 
>> root timing utils tfp 7 -- returned KO = 0.9994965
> 
> 5 ? tfp 7
> KO = 0.9994965
> 
>> root timing utils gain -- returned gain now:20 (There seems to be a
> 
> 6 ? gain
> gain now:-20
> 
>> root eng eeprom info -- returned 0024
> 
> Same here. Please note that to enable any eeprom writes you must close
> JP4 temporary.
> 
> By the way: you don't need to start every command with 'root'. It just
> resets the menu structure back start every time, which sounds
> impractical. You gan enter the menus, type '?' to see the available
> commands and go back to previous menu level with 'pop' command.
> 
>> Any thoughts on why I don't have a lock as yet?
> 
> According to A/D value it looks like clock steering is not working at
> all. You should use oscilloscope to find out if A/D values have any
> effect at all.
> 
> If you have rubidium or other kind of 10 MHz source put it to one trace
> of oscilloscope and TS2100 10 MHz output to another. Then try with
> different A/D values manually and see if it's even possible to get waves
> syncronized. If it's not possible with any A/D value then it will never
> lock, perhaps your OCXO is not compatible.
> 

-- 
---
Bruce Lane, ARS KC7GR
http://www.bluefeathertech.com
kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)
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Re: [time-nuts] Cheap jitter measurements

[Bob kb8tq]

Hi

Without the ability to put out a “known good” time pulse there is no quick way 
to 
check NTP. GPS modules suffer a similar issue. They put out a pulse and a 
“correction” (sawtooth error) to tell you what they just told you. Doing the 
same 
sort of thing with NTP may be possible. 

Indeed the process of correcting this sort of data is open to a bit of debate. 
It does 
give you a way to get around the “hey, all I can do is 300 ns” issue. With 
GPSDO’s
the correction is part of the standard firmware. It would be nice if one of the 
NTP 
guru’s popped up with an equivalent process. 

One *could* monitor various bits and pieces of the OS’s timing generation 
system. 
Somehow that does not seem quite as much fun as looking at the whole result all
at once. Indeed it might be the only way to get it all worked out.

Bob

> On Apr 8, 2018, at 6:14 PM, John Hawkinson  wrote:
> 
> Tom Van Baak  wrote on Sun,  8 Apr 2018
> at 12:36:52 -0700 in <55EB8D26CCDC4B1ABFBC53F95E4C0557@pc52>:
> 
>> My mental model of a black box computer running NTP
> ...
>> Imagine the black box has two BNC connectors; one accepts an input
>> pulse to be timed; one outputs a pulse at certain times.
> 
> Theory runs into reality. The problem is that NTP is easy to set up to do the 
> former, and hard to set up to do the latter. Where "easy" means "it's 
> commonly done" and "hard" means "I'm not aware that it's ever done" (not that 
> I'm so expert that I would necessarily know if it were).
> 
>> To me this better than relying on NTP to tell you how NTP is doing,
>> which as far as I can tell from live plots on the web, is all that
>> most people do. Instead use real, external, physical
>> measurement. The internal NTP stats are fine for tracking the
>> performance of the PLL, but don't confuse that with actual timing.
> 
> One of the things that NTP does is it reports on its status with respect to 
> other NTP peers. Yes, this is still "internal" to the "NTP universe," but 
> it's also external to the device you have in front of you.
> 
> For instance, my ntp server currently reports that it is offset between .6 
> and 2.1 millisecon
> ds from 7 ntp peers it is talking to, and there's at least some reason to 
> think these are not particularly correllated. That gives me reason to infer 
> that my server's clock is probably not off by more than a few milliseconds. 
> (This is not sub-ns timing, of course. It's intended to be illustrative. And 
> for a variety of reasons this particular server's network connection is a bit 
> unstable, so most NTP users can probably do a lot better.)
> 
> Yeah, that's not truly reliable, like I was comparing it to a truly external 
> reference, but it's also not as meaningless as staring at internal parameters.
> 
> Indeed, one way in practice that ntp people measure ntp is to wire up an 
> external reference to the "input BNC" of your black box, instruct the ntp 
> server to monitor that PPS input but not use it in the clock monkeying 
> algorithm, and then compare what NTP reports for the local clock with what it 
> reports for other NTP peers. 
> 
> --jh...@mit.edu
>  John Hawkinson
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Re: [time-nuts] Cheap jitter measurements

[Dana Whitlow]

Pity the poor man who has (n>1) clocks, for he knows not what time it is.

Dana


On Sun, Apr 8, 2018 at 4:29 PM, John Ackermann N8UR  wrote:

> I want to jump on Tom's post, and Bob's note at 1:14 on Saturday (that
> begins with "Just to be very clear..."  They both raise an important point
> about measurements.
>
> With both NTP and GPSDO measurements a lot of folks focus heavily on what
> the "black box" is reporting about itself.  But self-contained measurements
> are really unrelated to actual performance.
>
> As Bob mentioned, in a GPSDO you can look at tempco, humidco, voltageco,
> and all sorts of other things but the overall point of the system is to
> make those meaningless: the control loop(s) compensate for them.  If those
> internal error generators are reduced, it may make the system's work
> easier, but that improvement will have no effect on the quality of the
> output if the control loop is already properly compensating for it.
>
> And in NTP, the software reports all sorts of interesting measurements,
> but none of them really tell you how close the computer's clock is to a
> local reference.  As Tom said, the real test is how the time tick coming
> out of the box compares with the time tick going into it.
>
> The bottom line is that no self-contained measurement can tell you actual
> performance.  The *only* way to do that is to compare your box with an
> external reference whose error bounds are known.
>
> After all, this is why we're time-nuts -- every time you acquire a clock,
> you also need to acquire a better clock to test it with. :-)
>
> John
> 
>
> On 04/08/2018 03:36 PM, Tom Van Baak wrote:
>
>> What do you mean by "jitter" and what do you really want to do?
>
 I mean jitter as NTP defines jitter.  Whatever that is.

>>>
>>> I think you need to figure out what you want to do so you don't fool
>>> yourself.
>>>
>>> ntpd is a PLL.  There is a low pass filter in the control loop.  It will
>>> track the low frequency wander of the source.
>>>
>>
>> Gary, Hal, Leo,
>>
>> My mental model of a black box computer running NTP is that I should be
>> able to give it a pulse (e.g., via parallel, serial, GPIO) and it tells me
>> what time it was. Use a GPSDO / Rb / picDIV to generate precise pulses.
>> Compare the known time of the pulse with the time the box says it was.
>> Repeat many times, collect data, look at the statistics; just as we would
>> for any clock.
>>
>> Similarly, the box should be able to give me a pulse at a known time. In
>> this case it records the time it thinks the pulse went out, and your GPSDO
>> / Rb / TIC makes the actual measurement. Again, collect data and look at
>> the statistics; just as we would for any clock.
>>
>> Imagine the black box has two BNC connectors; one accepts an input pulse
>> to be timed; one outputs a pulse at certain times. This allows a complete
>> analysis of NTP operation. Should be true for both client or server. If you
>> get down to nanosecond levels make sure to use equal length cables.
>>
>> To me this better than relying on NTP to tell you how NTP is doing, which
>> as far as I can tell from live plots on the web, is all that most people
>> do. Instead use real, external, physical measurement. The internal NTP
>> stats are fine for tracking the performance of the PLL, but don't confuse
>> that with actual timing.
>>
>> So this is why I'm excited to hear Gary wants a Rb timebase and a sub-ns
>> counter. Someone will finally measure NTP for real, not rely on the
>> internal numbers of NTP measuring itself. Or at least I hope that's what
>> Gary is up to.
>>
>> /tvb
>>
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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Andy ZL3AG via time-nuts]

On 9/04/2018, at 3:52 AM, jimlux wrote:

> Test equipment tends to be aged - Unless you have a particular need for a HP 
> 600 series microwave signal generator, there are probably better sources 
> available much cheaper that use more modern components. In this day and age, 
> I don't think people should suffer through 141T spectrum analyzers or even a 
> 8568- Spend your money an a nice USB unit instead.
> 
Blasphemy!


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Re: [time-nuts] Cheap jitter measurements

[John Hawkinson]

Tom Van Baak  wrote on Sun,  8 Apr 2018
at 12:36:52 -0700 in <55EB8D26CCDC4B1ABFBC53F95E4C0557@pc52>:

> My mental model of a black box computer running NTP
...
> Imagine the black box has two BNC connectors; one accepts an input
> pulse to be timed; one outputs a pulse at certain times.

Theory runs into reality. The problem is that NTP is easy to set up to do the 
former, and hard to set up to do the latter. Where "easy" means "it's commonly 
done" and "hard" means "I'm not aware that it's ever done" (not that I'm so 
expert that I would necessarily know if it were).

> To me this better than relying on NTP to tell you how NTP is doing,
> which as far as I can tell from live plots on the web, is all that
> most people do. Instead use real, external, physical
> measurement. The internal NTP stats are fine for tracking the
> performance of the PLL, but don't confuse that with actual timing.

One of the things that NTP does is it reports on its status with respect to 
other NTP peers. Yes, this is still "internal" to the "NTP universe," but it's 
also external to the device you have in front of you.

For instance, my ntp server currently reports that it is offset between .6 and 
2.1 millisecon
ds from 7 ntp peers it is talking to, and there's at least some reason to think 
these are not particularly correllated. That gives me reason to infer that my 
server's clock is probably not off by more than a few milliseconds. (This is 
not sub-ns timing, of course. It's intended to be illustrative. And for a 
variety of reasons this particular server's network connection is a bit 
unstable, so most NTP users can probably do a lot better.)

Yeah, that's not truly reliable, like I was comparing it to a truly external 
reference, but it's also not as meaningless as staring at internal parameters.

Indeed, one way in practice that ntp people measure ntp is to wire up an 
external reference to the "input BNC" of your black box, instruct the ntp 
server to monitor that PPS input but not use it in the clock monkeying 
algorithm, and then compare what NTP reports for the local clock with what it 
reports for other NTP peers. 

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] Cheap jitter measurements

[Hal Murray]

kb...@n1k.org said:
> In both cases (pulse in and pulse out) the first step is to ask NTP “when
> was that?”. You still have a pretty big chunk of NTP in the  middle of the
> process …. If NTP only “knows” what is happening (or can control what is
> happening)  to +/- 300 ns. The guts of  your data will be limited to the
> same  300 ns.  

NTP itself doesn't actually do any timing measurements.  That is done by the 
OS.

I'm not familiar with Windows.  All my OS comments apply to Linux and *BSD.  
Windows is probably similar is most respects but may be missing details.

The system clock runs off the CPU crystal.  The kernel has a knob for fine 
tuning the clock speed.  There is another knob that says bump the clock speed 
a bit (500 PPM) long enough to adjust the time by X seconds.  ntpd uses both.

[Many years ago, most kernels used an interrupt from the battery backed clock 
(RTC or TOY) for the main timing and interpolated using the CPU clock.]


The kernel can capture a time stamp on a PPS pulse and on packet arrivals.  I 
don't know of anything similar for packet departure.

The kernel can support more than one PPS so you could feed a GPSDO in on one 
for NTP and use another for general timing measurements.  Those measurements 
are using the kernel clock as a reference.  You can turn ntpd off so the 
system time will have more long term drift but less short term wobble as ntpd 
corrects for errors.]


I don't know of a good way to get a pulse out at a specified time.  You can 
measure the time that user code sends a pulse out and setup a timer to go off 
every second.  I don't know how to adjust or specify the offset from 
timer-going-off to system clock ticking to another second.

The Linux kernel PPS code has an option to send a pulse out when one comes 
in.  I haven't played with it.  I think it could help with measuring the 
interrupt response delays.

tvb: If I send you some data, can you turn it into pretty graphs?





-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Cheap jitter measurements

[John Ackermann N8UR]

I want to jump on Tom's post, and Bob's note at 1:14 on Saturday (that 
begins with "Just to be very clear..."  They both raise an important 
point about measurements.


With both NTP and GPSDO measurements a lot of folks focus heavily on 
what the "black box" is reporting about itself.  But self-contained 
measurements are really unrelated to actual performance.


As Bob mentioned, in a GPSDO you can look at tempco, humidco, voltageco, 
and all sorts of other things but the overall point of the system is to 
make those meaningless: the control loop(s) compensate for them.  If 
those internal error generators are reduced, it may make the system's 
work easier, but that improvement will have no effect on the quality of 
the output if the control loop is already properly compensating for it.


And in NTP, the software reports all sorts of interesting measurements, 
but none of them really tell you how close the computer's clock is to a 
local reference.  As Tom said, the real test is how the time tick coming 
out of the box compares with the time tick going into it.


The bottom line is that no self-contained measurement can tell you 
actual performance.  The *only* way to do that is to compare your box 
with an external reference whose error bounds are known.


After all, this is why we're time-nuts -- every time you acquire a 
clock, you also need to acquire a better clock to test it with. :-)


John

On 04/08/2018 03:36 PM, Tom Van Baak wrote:

What do you mean by "jitter" and what do you really want to do?

I mean jitter as NTP defines jitter.  Whatever that is.


I think you need to figure out what you want to do so you don't fool yourself.

ntpd is a PLL.  There is a low pass filter in the control loop.  It will
track the low frequency wander of the source.


Gary, Hal, Leo,

My mental model of a black box computer running NTP is that I should be able to 
give it a pulse (e.g., via parallel, serial, GPIO) and it tells me what time it 
was. Use a GPSDO / Rb / picDIV to generate precise pulses. Compare the known 
time of the pulse with the time the box says it was. Repeat many times, collect 
data, look at the statistics; just as we would for any clock.

Similarly, the box should be able to give me a pulse at a known time. In this 
case it records the time it thinks the pulse went out, and your GPSDO / Rb / 
TIC makes the actual measurement. Again, collect data and look at the 
statistics; just as we would for any clock.

Imagine the black box has two BNC connectors; one accepts an input pulse to be 
timed; one outputs a pulse at certain times. This allows a complete analysis of 
NTP operation. Should be true for both client or server. If you get down to 
nanosecond levels make sure to use equal length cables.

To me this better than relying on NTP to tell you how NTP is doing, which as 
far as I can tell from live plots on the web, is all that most people do. 
Instead use real, external, physical measurement. The internal NTP stats are 
fine for tracking the performance of the PLL, but don't confuse that with 
actual timing.

So this is why I'm excited to hear Gary wants a Rb timebase and a sub-ns 
counter. Someone will finally measure NTP for real, not rely on the internal 
numbers of NTP measuring itself. Or at least I hope that's what Gary is up to.

/tvb

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Re: [time-nuts] Cheap jitter measurements

[Tom Van Baak]

>> Similarly, the box should be able to give me a pulse at a known time.
>
> how do you set up NTP to do that?

Don't know. That's not NTP's job. Any process that can query system time and 
get/set a GPIO bit will do. The question to be answered is how close to the 
real time (as in UTC(k), atomic clocks, GPS, etc.) is the fake time running 
inside the OS / CPU. The way you determine that is to send the fake time out, 
and/or to send real time in. A low-latency or zero-jitter GPIO pin would be 
required in either case.

> In both cases (pulse in and pulse out) the first step is to ask NTP “when was 
> that?”.
> You still have a pretty big chunk of NTP in the middle of the process …. If 
> NTP only
> “knows” what is happening (or can control what is happening)  to +/- 300 ns. 
> The guts of 
> your data will be limited to the same  300 ns. 

You don't need NTP for this experiment. That's kind of the idea. You run the PC 
/ SBC / R-Pi plain. Or you run it with NTP. Or different versions of NTP or 
different configs. Or you run it with a better xtal, or you replace the xtal 
with a GPSDO and DDS. So this isn't intended to be a hack on NTP per-se; it's 
more of a scientific testbed that you can drop NTP into. You'd get a nice set 
of phase and ADEV / TDEV / MTIE plots or something. I don't know.

I don't use NTP so take this all with a grain of salt. But from the looks of 
it, people playing (or developing) NTP fall into the same trap as some GPSDO 
developers: a focus on the performance of the PLL or other fancy internal 
colorful plots instead of real measurements of rising edges of electrons at the 
input and output.

This was easy back in the peek/poke parallel port days. Took a backseat in the 
serial and USB era. But now that many systems have GPIO ports it should be 
possible again. Anyway, Gary and Leo, et al. can report eventually what they 
find. This isn't really an NTP mailing list, but I would think some of the 
basic concepts of metrology should apply to OS timing as they do to h/w timing.

/tvb

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Re: [time-nuts] Weird Stuff Warehouse shutting down

[paul swed]

Really appreciate the video of Apex. I don't think words describe it very
well.
But everything is there and whats more interesting is if you are looking
for something they do have a pretty good idea of the location. Especially
if it has any value like new BNC connectors.
The time I went there I was dressed for business. Wrong attire. But I did
see the nooks and cranny's mentioned.
Never ripped my shirt and I did use the step ladders that get you to the
top rows.
But what seems to happen is your eyeballs simply get overloaded. Most gear
is on its side so that makes it harder to read.
Then the fact that its going to be tough to ship really puts a kink in the
digging.
No matter a really great video of the place.
Regards
Paul
WB8TSL

On Sun, Apr 8, 2018 at 11:37 AM, Azelio Boriani 
wrote:

> For those of us (like me) that can travel to the US less than once in
> a lifetime, there is an EEVblog #124 - A Tour of Apex Electronics:
>
> 
>
>
> On Sun, Apr 8, 2018 at 2:25 AM, Alexander Pummer  wrote:
> > other surplus:
> > https://www.google.com/search?client=firefox-b-1&tbm=lcl&ei=
> qGDJWrDzBuXm5gKB3bmQDw&q=electronic+surplus+bay+area+
> ca&oq=electronic+surplus+bay+area+ca&gs_l=psy-ab.12...
> 16142.25972.0.28698.14.12.2.0.0.0.228.1752.0j11j1.12.00.
> ..1c.1.64.psy-ab..0.0.00.qHdPqOyu4I8#rlfi=hd:;si:;mv:!
> 1m3!1d406993.57669817575!2d-122.07998499435485!3d37.
> 551234775823595!3m2!1i636!2i386!4f13.1
> >
> > 73
> >
> > KJ6UHN
> >
> > Alex
> >
> >
> > On 4/7/2018 4:03 PM, paul swed wrote:
> >>
> >> Like most of you I also visited these places and have dragged back and
> >> shipped lots of "Weird stuff". Even smaller parts through airport
> >> security.
> >> The oddest thing was 3/4" cable TV hardline connectors and there was no
> >> issue at all.
> >> It always made it fun to go on a business trip to the area and always
> slip
> >> a bit of time into visit the places.
> >> There may still be two left at this point. Electronic Surplus Sales or
> ESS
> >> and do not recall the name of the other. But do know its location be
> >> heart.
> >> I can say that in the 70s they really had an effect on my overall
> career.
> >> Piles of computer stuff and much else. Buy it by the pound. Think it was
> >> Mikes surplus by the Oakland airport. Long gone and one up in Berkley.
> >>
> >> There is one crazy place down in northern LA. Some what hard to get to
> but
> >> my god the stuff. Overwhelming. They dicker also. Nothing like a tough
> >> bargain was there 3 years ago.
> >>
> >>
> >> On Sat, Apr 7, 2018 at 10:36 AM, Bob kb8tq  wrote:
> >>
> >>> Hi
> >>>
> >>> Over the years, this has been the fate of a *lot* of surplus / goodie
> >>> outfits. They have
> >>> a “deal” on some property and that runs out. Sometimes it’s a sale with
> >>> the neighborhood
> >>> improving. Other times it’s the roof needing repairs and nobody sees
> the
> >>> need to do them
> >>> until it is way to late ….
> >>>
> >>> Bob
> >>>
>  On Apr 6, 2018, at 11:24 PM, Bruce Lane 
> >>>
> >>> wrote:
> 
>  Fellow techies,
> 
> I'm sorry to report we're losing another surplus place. Weird
>  Stuff
>  Warehouse, in Sunnyvale, CA, is closing its doors as of Monday,
>  9-Apr-18.
> 
> It seems we have Google to blame. Here's Weird Stuff's final
>  newsletter, verbatim.
> 
>  -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
>  April 6, 2018
> 
>  To Weirdstuff Customers,
> 
>  Sadly, after 32 years in business, Weirdstuff Warehouse will be
> closing
>  its doors as of April 9, 2018. If you have been following the real
>  estate news for Sunnyvale you know that Google purchased a large
> amount
>  of real estate in the area including the building we have been leasing
>  for the past 22 years. We have been asked to vacate the building as
> soon
>  as possible, and in order to accomplish that task we are selling our
>  inventory and many of our assets to Outback Equipment of Morgan Hill.
>  The transfer of inventory and assets will take place on April 9, 2018;
>  at that time Weirdstuff Warehouse will cease to do business.
> 
>  Even though Weirdstuff is closing we will retain ownership of the
>  Corporation, trademark, and domain names. We hope to handle these
>  entities and wind down the corporation before year end.
> 
>  Many of you have been loyal customers for many years, and we have
>  enjoyed working with you. We thank you for your loyalty and business.
> 
>  For more information, check out our website after Monday, April 9,
> 2018.
> 
>  WeirdStuff Warehouse
>  384 W. Caribbean Dr.
>  Sunnyvale, CA 94089
>  (408) 743-5650
>  --
> 
> Heh... So much for Google's favorite "Don't Be Evil" motto
> 
>  ---
>  Bruce Lane, ARS KC7GR
>  http://www.bluefeathertech.com
>  kyrrin (at) bluefeathertech dot com
>  "Quando Om

Re: [time-nuts] Help improving impedance measurement by having a better clock

[Bob kb8tq]

Hi

I believe we are talking about material impedances here rather than electrical 
impedance. One of the 
weird things about this is that frequency (as in frequency accuracy) *can* be a 
contributor to the resultant
error. Thus my original question about just what the concern actually is…..

Bob

> On Apr 8, 2018, at 4:52 PM, Brooke Clarke  wrote:
> 
> Hi Daniel:
> 
> If you're concerned with accuracy of impedance measurements you might want to 
> spent a lot of time studying "The Impedance Measurement Handbook", it's the 
> bible for this.  The way the measurement is made has a huge impact on the 
> accuracy.  For example using a vector network analyzer to measure an 
> impedance that's not near 50 Ohms causes poor results.
> http://prc68.com/I/Z.shtml#KeyDocs
> For frequencies low enough to use 4 Terminal Pair, that's the way to go.
> http://www.prc68.com/I/HP4274_4275_LCR.shtml#MeasMtd
> 
> -- 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> 
>  Original Message 
>> I´m a long time time-nuts lurker (I posted here just a dozen times). I make
>> a few impedance measurement systems for material analysis (i´m a single man
>> shop doing custom hardware for clients). Usually they´re based around a
>> STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
>> measure them back, a few calculations later we have modulus / phase. I
>> always used internal ADCs and DACs (12 bits each).
>> 
>> I now want to use external ADCs and DACs with more bits to push the limits,
>> but i´m afraid that the poor performance of the STM32 PLL that drives the
>> clock will get in the way, so I plan to drive the "load" of both DAC and
>> ADCs from an external signal derived from a TCXO using a clock divider.
>> 
>> To get some sense of how much things are improving (or not) I need to
>> somehow measure these clocks and get a meaningfull measurement about how
>> good (or bad) they are.
>> 
>> The tools I have are a Hameg HM8123 with a 10MHz OCXO I shoehorned inside
>> and a Picotest U6200A with original OCXO. I can log period information from
>> both using serial/USB port. I can make a histogram of the data. I don´t
>> have any better idea about what to do and would like to hear from you :)
>> 
>> Daniel
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>> 
> 
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Re: [time-nuts] Help improving impedance measurement by having a better clock

[Brooke Clarke]

Hi Daniel:

If you're concerned with accuracy of impedance measurements you might want to spent a lot of time studying "The 
Impedance Measurement Handbook", it's the bible for this.  The way the measurement is made has a huge impact on the 
accuracy.  For example using a vector network analyzer to measure an impedance that's not near 50 Ohms causes poor results.

http://prc68.com/I/Z.shtml#KeyDocs
For frequencies low enough to use 4 Terminal Pair, that's the way to go.
http://www.prc68.com/I/HP4274_4275_LCR.shtml#MeasMtd

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 

I´m a long time time-nuts lurker (I posted here just a dozen times). I make
a few impedance measurement systems for material analysis (i´m a single man
shop doing custom hardware for clients). Usually they´re based around a
STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
measure them back, a few calculations later we have modulus / phase. I
always used internal ADCs and DACs (12 bits each).

I now want to use external ADCs and DACs with more bits to push the limits,
but i´m afraid that the poor performance of the STM32 PLL that drives the
clock will get in the way, so I plan to drive the "load" of both DAC and
ADCs from an external signal derived from a TCXO using a clock divider.

To get some sense of how much things are improving (or not) I need to
somehow measure these clocks and get a meaningfull measurement about how
good (or bad) they are.

The tools I have are a Hameg HM8123 with a 10MHz OCXO I shoehorned inside
and a Picotest U6200A with original OCXO. I can log period information from
both using serial/USB port. I can make a histogram of the data. I don´t
have any better idea about what to do and would like to hear from you :)

Daniel
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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Tim Shoppa]

C&H was SUPERB for test equipment in the 1990's when the aviation industry
in Southern California was downsizing.

IMHO not nearly so interesting today. Unless you're into pneumatics in
which case they are a delight.

Tim N3QE

On Sun, Apr 8, 2018 at 10:36 AM, paul swed  wrote:

> Thanks
> It has to have been Apex that I visited. The back areas were a mix of open
> sky and sort of sheds.
> The air was typically pretty dry so the stuff held up well. There were
> things I would have liked to have grabbed.
> Could easily see a day digging around.
> Inside its stacked to the 20 ft ceilings and they have ladders like you see
> in home depot to get to the top.
> There was a genrad admittance bridge on the top shelf. In good condition
> and in the nice wood box.
> I did not go to C&H as I simply ran out of time. Pretty good?
> Regards
> Paul
> WB8TSL
>
> On Sun, Apr 8, 2018 at 12:18 AM, Jeff Woolsey  wrote:
>
> > Geez.  The Agilent IEEE-1588 units I mentioned a month or two ago were
> > the last things I bought there.
> >
> >
> > > There is one crazy place down in northern LA. Some what hard to get to
> > but
> > > my god the stuff. Overwhelming. They dicker also. Nothing like a tough
> > > bargain was there 3 years ago.
> >
> > I happen to have returned from a family spring break in LA/SD just
> > today.  Yesterday I visted C&H surplus in Duarte and picked up a couple
> > items, one was way-underpriced.  This morning I was at APEX Electronics
> > in Sun Valley.  Overwhelming is right.  Being where they are in LA they
> > have a fair amount of prop business.   Imagine the backroom at
> > WeirdStuff. Now imagine ther same thing, only open to the sky, out
> > back.  I inquired about a couple items near the front, but didn't have
> > room in the car (or my wallet) for them.  The Yelp reviews are accurate.
> >
> > --
> > Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
> > Nature abhors straight antennas, clean lenses, and empty storage
> > "Delete! Delete! OK!" -Dr. Bronner on disk space management
> > Card-sorting, Joel.  -Crow on solitaire
> >
> > ___
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> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
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Re: [time-nuts] Cheap jitter measurements

[Bob kb8tq]

Hi

Ok, I’ll bite ….

> On Apr 8, 2018, at 3:36 PM, Tom Van Baak  wrote:
> 
 What do you mean by "jitter" and what do you really want to do?
>>> I mean jitter as NTP defines jitter.  Whatever that is.
>> 
>> I think you need to figure out what you want to do so you don't fool 
>> yourself.
>> 
>> ntpd is a PLL.  There is a low pass filter in the control loop.  It will 
>> track the low frequency wander of the source.
> 
> Gary, Hal, Leo,
> 
> My mental model of a black box computer running NTP is that I should be able 
> to give it a pulse (e.g., via parallel, serial, GPIO) and it tells me what 
> time it was. Use a GPSDO / Rb / picDIV to generate precise pulses. Compare 
> the known time of the pulse with the time the box says it was. Repeat many 
> times, collect data, look at the statistics; just as we would for any clock.
> 
> Similarly, the box should be able to give me a pulse at a known time.

how do you set up NTP to do that?

> In this case it records the time it thinks the pulse went out, and your GPSDO 
> / Rb / TIC makes the actual measurement. Again, collect data and look at the 
> statistics; just as we would for any clock.
> 
> Imagine the black box has two BNC connectors; one accepts an input pulse to 
> be timed; one outputs a pulse at certain times. This allows a complete 
> analysis of NTP operation. Should be true for both client or server. If you 
> get down to nanosecond levels make sure to use equal length cables.
> 
> To me this better than relying on NTP to tell you how NTP is doing, which as 
> far as I can tell from live plots on the web, is all that most people do. 
> Instead use real, external, physical measurement. The internal NTP stats are 
> fine for tracking the performance of the PLL, but don't confuse that with 
> actual timing.
> 
> So this is why I'm excited to hear Gary wants a Rb timebase and a sub-ns 
> counter. Someone will finally measure NTP for real, not rely on the internal 
> numbers of NTP measuring itself. Or at least I hope that's what Gary is up to.

In both cases (pulse in and pulse out) the first step is to ask NTP “when was 
that?”. You still have a pretty big chunk of NTP in the 
middle of the process …. If NTP only “knows” what is happening (or can control 
what is happening)  to +/- 300 ns. The guts of 
your data will be limited to the same  300 ns. 

Bob

> 
> /tvb
> 
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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Jeff Woolsey]

> Thanks
> It has to have been Apex that I visited. The back areas were a mix of open
> sky and sort of sheds.
> The air was typically pretty dry so the stuff held up well.
I did see some populated circuit boards absolutely caked with dirt (was
probably dust at first). Maybe not just outside, either.
> There were
> things I would have liked to have grabbed.
> Could easily see a day digging around.
> Inside its stacked to the 20 ft ceilings and they have ladders like
> you see
> in home depot to get to the top.
I didn't see any ladders, but I didn't look everywhere (too dangerous)
and I wasn't dressed for it.  I told the guy I wasn't tall enough to
shop there (could not read model numbers of test equipment 15 feet up).

I inquired about a Tek 465B ($50) and Tek 1910 ($100).  Those weren't
irresistible bargains, and I'm already trying to fix a similar scope.
Everything is as-is where-is.  Didn't ask about a Tek T932, either.

It reminded me a bit of AxMan Surplus in Minneapolis (where I didn't buy
a 465M for $75, either).

>
> I did not go to C&H as I simply ran out of time. Pretty good?
I'd say it's an appetizer for the Silicon Valley stores.  (APEX is in a
league of its own.)  I picked up a Fluke 1900A multi-counter for $20
because of the engraved tag on it "GIFT FROM / JOHN FLUKE / MARCH 1986".
There's one left. Alas, they're only 6 digits, but have very sharp LEDs
for kHz, MHz, and Overflow.  A SHARP EL-5120 with LCD faults overpriced
at $5.  And an ailing GC-1000H clock.  Other stuff I took pictures of
include a Fluke 1953A, an HP 8006B? Pulse Generator, an EDC Programmable
DC Voltage Standard, and an external dbx dBm  meter.   There's also a
Tek 7704A with 7A26, 7A15A, 7D11, 7D12/M2 sitting on a 203 scopemobile
(and an empty one with just plugins (5B31, 7B80, 7A12, 7A19)) outside
the front door (much like Halted/HSC did at their previous location) for
$50 (just the 7704A).  I didn't have room in the car for it.

C&H days/hours are limited; I lucked out.

> Regards
> Paul
> WB8TSL

-- 
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire

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Re: [time-nuts] Cheap jitter measurements

[Tom Van Baak]

>>> What do you mean by "jitter" and what do you really want to do?
>> I mean jitter as NTP defines jitter.  Whatever that is.
> 
> I think you need to figure out what you want to do so you don't fool yourself.
> 
> ntpd is a PLL.  There is a low pass filter in the control loop.  It will 
> track the low frequency wander of the source.

Gary, Hal, Leo,

My mental model of a black box computer running NTP is that I should be able to 
give it a pulse (e.g., via parallel, serial, GPIO) and it tells me what time it 
was. Use a GPSDO / Rb / picDIV to generate precise pulses. Compare the known 
time of the pulse with the time the box says it was. Repeat many times, collect 
data, look at the statistics; just as we would for any clock.

Similarly, the box should be able to give me a pulse at a known time. In this 
case it records the time it thinks the pulse went out, and your GPSDO / Rb / 
TIC makes the actual measurement. Again, collect data and look at the 
statistics; just as we would for any clock.

Imagine the black box has two BNC connectors; one accepts an input pulse to be 
timed; one outputs a pulse at certain times. This allows a complete analysis of 
NTP operation. Should be true for both client or server. If you get down to 
nanosecond levels make sure to use equal length cables.

To me this better than relying on NTP to tell you how NTP is doing, which as 
far as I can tell from live plots on the web, is all that most people do. 
Instead use real, external, physical measurement. The internal NTP stats are 
fine for tracking the performance of the PLL, but don't confuse that with 
actual timing.

So this is why I'm excited to hear Gary wants a Rb timebase and a sub-ns 
counter. Someone will finally measure NTP for real, not rely on the internal 
numbers of NTP measuring itself. Or at least I hope that's what Gary is up to.

/tvb

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Re: [time-nuts] NEO-7 GPS default 1pps width?

[Leo Bodnar]

Yes, that's exactly how Ublox default PPS setting works.
Pulse is positive - rising edge is "the time."
Leo

On 8 Apr 2018, at 17:00, time-nuts-requ...@febo.com wrote:

> The manual says pulseLenRatio is zero and pulseLenRatioLock is 100,000 (us)
> flags-lockedOtherSet is 1, so I think that means "only generate 100ms 
> pulses when locked"
> 
> Does that align with anyone else's experience?

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Re: [time-nuts] NEO-7 GPS default 1pps width?

[Mike Cook]

I have 6M and 8M and they are both 100ms 1PPS signals. Interpolate.

> Le 8 avr. 2018 à 15:51, jimlux  a écrit :
> 
> I've got some NEO-7Ms here, and without an oscilloscope handy - what's the 
> factory default 1pps pulse width?
> 
> The manual says pulseLenRatio is zero and pulseLenRatioLock is 100,000 (us)
> flags-lockedOtherSet is 1, so I think that means "only generate 100ms pulses 
> when locked"
> 
> 
> Does that align with anyone else's experience?
> 
> Tnx
> Jim
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Don’t worry about how powerful the machines are. Worry about who the machines 
are giving  power to.

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Re: [time-nuts] Weird Stuff WareHouse shutting down

[jimlux]

On 4/8/18 7:36 AM, paul swed wrote:

Thanks
It has to have been Apex that I visited. The back areas were a mix of open
sky and sort of sheds.


Don't want to be there in an earthquake.  After the Northridge quake, 
they had to rearrange their outdoor maze to improve safety somewhat.




The air was typically pretty dry so the stuff held up well. There were
things I would have liked to have grabbed.
Could easily see a day digging around.


Indeed - the only problem I have with Apex is that if what you're 
looking at is junk, but would look good on a set, they can make more 
money renting it to a production than selling it - and it's priced 
accordingly.  Anything with a rack full of blinky-lights panels has 
likely been rewired to be "blinky lights".


They have (or used to, haven't been there in about 5-6 years) an 
excellent selection of multi pin circular connectors at reasonable 
prices - very handy if you've got some surplus gear with no cables.


Test equipment tends to be aged - Unless you have a particular need for 
a HP 600 series microwave signal generator, there are probably better 
sources available much cheaper that use more modern components. In this 
day and age, I don't think people should suffer through 141T spectrum 
analyzers or even a 8568- Spend your money an a nice USB unit instead.





Inside its stacked to the 20 ft ceilings and they have ladders like you see
in home depot to get to the top.
There was a genrad admittance bridge on the top shelf. In good condition
and in the nice wood box.
I did not go to C&H as I simply ran out of time. Pretty good?
Regards
Paul
WB8TSL

On Sun, Apr 8, 2018 at 12:18 AM, Jeff Woolsey  wrote:


Geez.  The Agilent IEEE-1588 units I mentioned a month or two ago were
the last things I bought there.



There is one crazy place down in northern LA. Some what hard to get to

but

my god the stuff. Overwhelming. They dicker also. Nothing like a tough
bargain was there 3 years ago.


I happen to have returned from a family spring break in LA/SD just
today.  Yesterday I visted C&H surplus in Duarte and picked up a couple
items, one was way-underpriced.  This morning I was at APEX Electronics
in Sun Valley.  Overwhelming is right.  Being where they are in LA they
have a fair amount of prop business.   Imagine the backroom at
WeirdStuff. Now imagine ther same thing, only open to the sky, out
back.  I inquired about a couple items near the front, but didn't have
room in the car (or my wallet) for them.  The Yelp reviews are accurate.

--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire

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Re: [time-nuts] Weird Stuff Warehouse shutting down

[Azelio Boriani]

For those of us (like me) that can travel to the US less than once in
a lifetime, there is an EEVblog #124 - A Tour of Apex Electronics:




On Sun, Apr 8, 2018 at 2:25 AM, Alexander Pummer  wrote:
> other surplus:
> https://www.google.com/search?client=firefox-b-1&tbm=lcl&ei=qGDJWrDzBuXm5gKB3bmQDw&q=electronic+surplus+bay+area+ca&oq=electronic+surplus+bay+area+ca&gs_l=psy-ab.12...16142.25972.0.28698.14.12.2.0.0.0.228.1752.0j11j1.12.00...1c.1.64.psy-ab..0.0.00.qHdPqOyu4I8#rlfi=hd:;si:;mv:!1m3!1d406993.57669817575!2d-122.07998499435485!3d37.551234775823595!3m2!1i636!2i386!4f13.1
>
> 73
>
> KJ6UHN
>
> Alex
>
>
> On 4/7/2018 4:03 PM, paul swed wrote:
>>
>> Like most of you I also visited these places and have dragged back and
>> shipped lots of "Weird stuff". Even smaller parts through airport
>> security.
>> The oddest thing was 3/4" cable TV hardline connectors and there was no
>> issue at all.
>> It always made it fun to go on a business trip to the area and always slip
>> a bit of time into visit the places.
>> There may still be two left at this point. Electronic Surplus Sales or ESS
>> and do not recall the name of the other. But do know its location be
>> heart.
>> I can say that in the 70s they really had an effect on my overall career.
>> Piles of computer stuff and much else. Buy it by the pound. Think it was
>> Mikes surplus by the Oakland airport. Long gone and one up in Berkley.
>>
>> There is one crazy place down in northern LA. Some what hard to get to but
>> my god the stuff. Overwhelming. They dicker also. Nothing like a tough
>> bargain was there 3 years ago.
>>
>>
>> On Sat, Apr 7, 2018 at 10:36 AM, Bob kb8tq  wrote:
>>
>>> Hi
>>>
>>> Over the years, this has been the fate of a *lot* of surplus / goodie
>>> outfits. They have
>>> a “deal” on some property and that runs out. Sometimes it’s a sale with
>>> the neighborhood
>>> improving. Other times it’s the roof needing repairs and nobody sees the
>>> need to do them
>>> until it is way to late ….
>>>
>>> Bob
>>>
 On Apr 6, 2018, at 11:24 PM, Bruce Lane 
>>>
>>> wrote:

 Fellow techies,

I'm sorry to report we're losing another surplus place. Weird
 Stuff
 Warehouse, in Sunnyvale, CA, is closing its doors as of Monday,
 9-Apr-18.

It seems we have Google to blame. Here's Weird Stuff's final
 newsletter, verbatim.

 -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

 April 6, 2018

 To Weirdstuff Customers,

 Sadly, after 32 years in business, Weirdstuff Warehouse will be closing
 its doors as of April 9, 2018. If you have been following the real
 estate news for Sunnyvale you know that Google purchased a large amount
 of real estate in the area including the building we have been leasing
 for the past 22 years. We have been asked to vacate the building as soon
 as possible, and in order to accomplish that task we are selling our
 inventory and many of our assets to Outback Equipment of Morgan Hill.
 The transfer of inventory and assets will take place on April 9, 2018;
 at that time Weirdstuff Warehouse will cease to do business.

 Even though Weirdstuff is closing we will retain ownership of the
 Corporation, trademark, and domain names. We hope to handle these
 entities and wind down the corporation before year end.

 Many of you have been loyal customers for many years, and we have
 enjoyed working with you. We thank you for your loyalty and business.

 For more information, check out our website after Monday, April 9, 2018.

 WeirdStuff Warehouse
 384 W. Caribbean Dr.
 Sunnyvale, CA 94089
 (408) 743-5650
 --

Heh... So much for Google's favorite "Don't Be Evil" motto

 ---
 Bruce Lane, ARS KC7GR
 http://www.bluefeathertech.com
 kyrrin (at) bluefeathertech dot com
 "Quando Omni Flunkus Moritati" (Red Green)
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
>>>
>>> mailman/listinfo/time-nuts

 and follow the instructions there.
>>>
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
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>>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
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>>
>
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_

Re: [time-nuts] Meinberg (Rode & Schwartz), ED170MP GPS Receiver

[Azelio Boriani]

I think you can use the GPSMON32 with the ED170

I have an ED167MP, it works only with its downconverter antenna and
the rear panel has 2 serial ports and a network connection (a
Lantronix serial_port/telnet adapter, a simple serial port over
ethernet).

On Sun, Apr 8, 2018 at 1:23 PM, Martin Burnicki
 wrote:
> Time wrote:
>> Does anyone have any information for the Meinberg (Rode & Schwartz), ED170MP
>> GPS Receiver?
>
> If you send email to techsupp...@meinberg.de then I'm sure my colleagues
> of the support group can help. It would be good if you specify a little
> bit more detailed which information you're interested in.
>
> Martin
> (working @Meinberg)
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Re: [time-nuts] Weird Stuff WareHouse shutting down

[paul swed]

Thanks
It has to have been Apex that I visited. The back areas were a mix of open
sky and sort of sheds.
The air was typically pretty dry so the stuff held up well. There were
things I would have liked to have grabbed.
Could easily see a day digging around.
Inside its stacked to the 20 ft ceilings and they have ladders like you see
in home depot to get to the top.
There was a genrad admittance bridge on the top shelf. In good condition
and in the nice wood box.
I did not go to C&H as I simply ran out of time. Pretty good?
Regards
Paul
WB8TSL

On Sun, Apr 8, 2018 at 12:18 AM, Jeff Woolsey  wrote:

> Geez.  The Agilent IEEE-1588 units I mentioned a month or two ago were
> the last things I bought there.
>
>
> > There is one crazy place down in northern LA. Some what hard to get to
> but
> > my god the stuff. Overwhelming. They dicker also. Nothing like a tough
> > bargain was there 3 years ago.
>
> I happen to have returned from a family spring break in LA/SD just
> today.  Yesterday I visted C&H surplus in Duarte and picked up a couple
> items, one was way-underpriced.  This morning I was at APEX Electronics
> in Sun Valley.  Overwhelming is right.  Being where they are in LA they
> have a fair amount of prop business.   Imagine the backroom at
> WeirdStuff. Now imagine ther same thing, only open to the sky, out
> back.  I inquired about a couple items near the front, but didn't have
> room in the car (or my wallet) for them.  The Yelp reviews are accurate.
>
> --
> Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
> Nature abhors straight antennas, clean lenses, and empty storage
> "Delete! Delete! OK!" -Dr. Bronner on disk space management
> Card-sorting, Joel.  -Crow on solitaire
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] Weird Stuff Warehouse shutting down

[Alexander Pummer]

other surplus: 
https://www.google.com/search?client=firefox-b-1&tbm=lcl&ei=qGDJWrDzBuXm5gKB3bmQDw&q=electronic+surplus+bay+area+ca&oq=electronic+surplus+bay+area+ca&gs_l=psy-ab.12...16142.25972.0.28698.14.12.2.0.0.0.228.1752.0j11j1.12.00...1c.1.64.psy-ab..0.0.00.qHdPqOyu4I8#rlfi=hd:;si:;mv:!1m3!1d406993.57669817575!2d-122.07998499435485!3d37.551234775823595!3m2!1i636!2i386!4f13.1


73

KJ6UHN

Alex


On 4/7/2018 4:03 PM, paul swed wrote:

Like most of you I also visited these places and have dragged back and
shipped lots of "Weird stuff". Even smaller parts through airport security.
The oddest thing was 3/4" cable TV hardline connectors and there was no
issue at all.
It always made it fun to go on a business trip to the area and always slip
a bit of time into visit the places.
There may still be two left at this point. Electronic Surplus Sales or ESS
and do not recall the name of the other. But do know its location be heart.
I can say that in the 70s they really had an effect on my overall career.
Piles of computer stuff and much else. Buy it by the pound. Think it was
Mikes surplus by the Oakland airport. Long gone and one up in Berkley.

There is one crazy place down in northern LA. Some what hard to get to but
my god the stuff. Overwhelming. They dicker also. Nothing like a tough
bargain was there 3 years ago.


On Sat, Apr 7, 2018 at 10:36 AM, Bob kb8tq  wrote:


Hi

Over the years, this has been the fate of a *lot* of surplus / goodie
outfits. They have
a “deal” on some property and that runs out. Sometimes it’s a sale with
the neighborhood
improving. Other times it’s the roof needing repairs and nobody sees the
need to do them
until it is way to late ….

Bob


On Apr 6, 2018, at 11:24 PM, Bruce Lane 

wrote:

Fellow techies,

   I'm sorry to report we're losing another surplus place. Weird Stuff
Warehouse, in Sunnyvale, CA, is closing its doors as of Monday, 9-Apr-18.

   It seems we have Google to blame. Here's Weird Stuff's final
newsletter, verbatim.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

April 6, 2018

To Weirdstuff Customers,

Sadly, after 32 years in business, Weirdstuff Warehouse will be closing
its doors as of April 9, 2018. If you have been following the real
estate news for Sunnyvale you know that Google purchased a large amount
of real estate in the area including the building we have been leasing
for the past 22 years. We have been asked to vacate the building as soon
as possible, and in order to accomplish that task we are selling our
inventory and many of our assets to Outback Equipment of Morgan Hill.
The transfer of inventory and assets will take place on April 9, 2018;
at that time Weirdstuff Warehouse will cease to do business.

Even though Weirdstuff is closing we will retain ownership of the
Corporation, trademark, and domain names. We hope to handle these
entities and wind down the corporation before year end.

Many of you have been loyal customers for many years, and we have
enjoyed working with you. We thank you for your loyalty and business.

For more information, check out our website after Monday, April 9, 2018.

WeirdStuff Warehouse
384 W. Caribbean Dr.
Sunnyvale, CA 94089
(408) 743-5650
--

   Heh... So much for Google's favorite "Don't Be Evil" motto

---
Bruce Lane, ARS KC7GR
http://www.bluefeathertech.com
kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)
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Re: [time-nuts] Tbolt temperature sensitivity.

[Bob kb8tq]

Hi

Back a while, I ran a fleet of TBolt’s and other GPSDO’s for quite a while. 
They all ran into HP counters to monitor the PPS outputs. I never saw
any of them hit or slip at the 100 ns level. Indeed different GPSDO 
firmware does the time / frequency tradeoff differently.  I’ve also run them
against various Cs standards. The results there were pretty much the same. 

None of the environments I was running in were very crazy. They all held a 
couple degrees C and the cycles were in the one hour-ish range. 

Bob

> On Apr 8, 2018, at 8:30 AM, John Green  wrote:
> 
> I don't use what LH says about temperature. I compare the 10 MHz output to
> something else. With two Tbolts sitting about 2 feet apart on my bench,
> both fed from the same antenna, both with factory settings, when the heat
> kicks on, I see a change in the difference between the two. Comparing a
> Tbolt to another, different GPSDO, the effect is even greater. Next step is
> to compare the Tbolt to a rubidium source that has been adjusted to match
> the Tbolt as closely as possible at a stable temperature. I suppose you
> could say the the Tbolt stays *locked* to GPS since the difference never
> gets to 100 nS, meaning they are always within 1 Hz. What I usually see
> when comparing the Tbolt to another, different model GPSDO is that the time
> difference between the two 10 MHz signals slips at a fairly constant rate,
> going from zero past 100 nS, and then through zero, over and over. I also
> tried comparing the 1 PPS and the time jumped around quite a bit. Since I
> plan to actually use 10 MHz instead of 1 PPS, I decided to quit looking at
> 1 PPS.
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[time-nuts] Tbolt temperature sensitivity.

[John Green]

I don't use what LH says about temperature. I compare the 10 MHz output to
something else. With two Tbolts sitting about 2 feet apart on my bench,
both fed from the same antenna, both with factory settings, when the heat
kicks on, I see a change in the difference between the two. Comparing a
Tbolt to another, different GPSDO, the effect is even greater. Next step is
to compare the Tbolt to a rubidium source that has been adjusted to match
the Tbolt as closely as possible at a stable temperature. I suppose you
could say the the Tbolt stays *locked* to GPS since the difference never
gets to 100 nS, meaning they are always within 1 Hz. What I usually see
when comparing the Tbolt to another, different model GPSDO is that the time
difference between the two 10 MHz signals slips at a fairly constant rate,
going from zero past 100 nS, and then through zero, over and over. I also
tried comparing the 1 PPS and the time jumped around quite a bit. Since I
plan to actually use 10 MHz instead of 1 PPS, I decided to quit looking at
1 PPS.
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[time-nuts] NEO-7 GPS default 1pps width?

[jimlux]

I've got some NEO-7Ms here, and without an oscilloscope handy - what's 
the factory default 1pps pulse width?


The manual says pulseLenRatio is zero and pulseLenRatioLock is 100,000 (us)
flags-lockedOtherSet is 1, so I think that means "only generate 100ms 
pulses when locked"



Does that align with anyone else's experience?

Tnx
Jim
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Re: [time-nuts] Meinberg (Rode & Schwartz), ED170MP GPS Receiver

[Martin Burnicki]

Time wrote:
> Does anyone have any information for the Meinberg (Rode & Schwartz), ED170MP
> GPS Receiver?

If you send email to techsupp...@meinberg.de then I'm sure my colleagues
of the support group can help. It would be good if you specify a little
bit more detailed which information you're interested in.

Martin
(working @Meinberg)
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Re: [time-nuts] Help improving impedance measurement by having a better clock

[Attila Kinali]

On Sat, 7 Apr 2018 22:54:42 -0300
Daniel Mendes  wrote:

> I´m a long time time-nuts lurker (I posted here just a dozen times). I make
> a few impedance measurement systems for material analysis (i´m a single man
> shop doing custom hardware for clients). Usually they´re based around a
> STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
> measure them back, a few calculations later we have modulus / phase. I
> always used internal ADCs and DACs (12 bits each).

The STM32's are known for their poorly performing ADCs and DACs,
even using an external one with the same bit width will increase
your performance. That said, what is your actual sample rate?
I would guess, if you use the timer unit to generate the pulses,
your jitter would be less than 10ps rms, probably even less than 1ps rms.
10ps rms limits your resolution to something like 14-15bit @500kHz,
1ps rms should be around 18bits, if I'm not mistaken. 

To measure the performance, I would just build the device and feed it
with an appropriate sine wave. Then analyze the SNR and spurs of the
sampled signal.

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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