Re: [time-nuts] Thermal effects on cables

I should have mentioned this in the original post - the measurements were not taken on the same cable length. Beware, and consult paper. Ole On Fri, Jan 13, 2017 at 7:52 AM, Ole Petter Ronningen wrote: > Hi, all > > The question of phase shifts in cables pops up every

[time-nuts] Thermal effects on cables

Hi, all The question of phase shifts in cables pops up every now and then on this list - I stumbled across a good table of measured phase shifts with temperature in different cable types in this paper: http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_PresentationWSchaefer.pdf

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

Hi > On Jan 12, 2017, at 4:06 PM, Bob Stewart wrote: > > Hi Bob, > OK, like Bugs Bunny, I'll venture out on the limb, cut the limb, and see > whether I fall or the tree falls: > Wouldn't it take 1801 samples to get 18 seconds at 100S tau? Maybe I didn't > state that

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

Hi Tom, I seem to remember a discussion of overlapping vs contiguous ADEV from some time ago.  So, I did a websearch, and this showed up from your site.  NB this is a link to a pdf file. leapsecond.com/hsn2006/pendulum-tides-ch2.pdf Bob From: Tom Van Baak To:

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

Bob, The minimal C code for (back-to-back or overlapping) ADEV is: stride = overlap ? 1 : tau; for (sum = n = i = 0; (i + 2*tau) < count; i += stride, n += 1) sum += pow(phase[i + 2*tau] - 2 * phase[i + tau] + phase[i], 2); return sqrt(sum / 2 / n) / tau; See adev_lib.c

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

The pesudo code for the Adev is quite easy to interpret. For a frequency record of N samples For each tau=M samples Reshape(N/M,M) Mean Diff Rms End On Thu, Jan 12, 2017 at 4:11 PM Bob Stewart wrote: > Hi Bob, > > OK, like Bugs Bunny, I'll venture out on the

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

Hi Bob, OK, like Bugs Bunny, I'll venture out on the limb, cut the limb, and see whether I fall or the tree falls: Wouldn't it take 1801 samples to get 18 seconds at 100S tau?  Maybe I didn't state that properly, but I think you get my meaning.  Also, I've never actually taken the time to look

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

Hi Keep in mind that when you do 1800 samples at 1 second, that data will only meet the 100 sample requirement out to tau = 18 seconds. Past that you are in the “under 100 samples region”. Bob > On Jan 12, 2017, at 2:32 PM, Bob Stewart wrote: > > Hi Bob, > OK, thanks for

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

Hi Bob, OK, thanks for explaining.  When you and others use highly technical terms like "small number of samples" it's not always clear to me what you mean.  =)  Ten samples?  That's not enough for anything.  Normally I run at least 1800 samples; at least if I plan to share them with someone.

Re: [time-nuts] Datum 9520-1000

Gary - The Datum 9520 series are Time Code Displays (discontinued). They have been appearing via government and military surplus via obsolescence sales. In addition to the 6-digit time display of the 9520 series, this specific model (-1000) includes the 3-digit Day of Year (DoY). I believe

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

Hi It varies from 5370 to 5370. You see a lot of plots that run out to 10 samples or less. Anything below 100 samples is risky in some senses. Bob > On Jan 12, 2017, at 12:25 PM, Bob Stewart wrote: > > Hi Bob, > OK, what's a small number of data points? Attached is a

[time-nuts] Service info for HP/Symmetricom 58502A 10MHz distribution amp?

Hi, I've got an HP/Symmetricom 58502A 10MHz frequency reference distribution amplifier. It has two 10MHz signal inputs and it auto-switches between inputs if one of them goes down. The 58502A had been working fine for the couple of years that I've had it, but recently it failed in a

[time-nuts] Datum 9520-1000

I am looking for documentation for a Datum 9520-1000 time code display. Thanks Gary ___ 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.

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

Hi There is a big difference between RMS and single shot. Single shot, the 5370 is a very different beast. That’s not a big deal when you have a few thousand readings and it all averages down. Unfortunately we all love to do runs with a very small number of points and then draw conclusions

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

Hi Bob, Normally I see somewhere between 2E-11 and 4E-11 at 1S tau on my 5370A, as in the blue trace on the attached plot.  Am I misunderstanding your meaning?  Granted, I am clocking the 5370A with a GPSDO, but I believe I see about the same thing with the HP10811.  This test was 1PPS vs 1PPS

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

Hi There are a number of ways to improve the resolution (and accuracy) of your data without spending big piles of cash. They have been discussed here on the list many times over the last few years. What I’m suggesting is that you dig into that ahead of taking data. You will dive into it

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

On 12 January 2017 at 02:31, Bob Camp wrote: > Hi > Hi Bob > > The most basic issue you are going to run into is that your counter is not > high enough > resolution / accuracy to give you meaningful data for time intervals under > a few hundred > seconds. Is that true if I'm