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 <b...@evoria.net> wrote: > > Hi Bob, > OK, what's a small number of data points? Attached is a screencap of > captures for 25, 50, 75, 100, and 150 seconds. Yeah, at 25 seconds, the 1S > tau is up at 4.56E-11, but it falls pretty quickly. I will mention that this > particular 5370 is much better than my other one. So, maybe this one is an > exceptional example? > > Just for grins, I also included a screencap of the phase points. > > Bob ----------------------------------------------------------------- > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > From: Bob Camp <kb...@n1k.org> > To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency > measurement <time-nuts@febo.com> > Sent: Thursday, January 12, 2017 11:04 AM > Subject: Re: [time-nuts] General questions about making measurements with > time interval counter. > > Hi > > There is a big difference between RMS and single shot. Single shot, the 5370 > is a very different beast. > That’s not a big deal when you have a few thousand readings and it all > averages down. Unfortunately > we all love to do runs with a very small number of points and then draw > conclusions from them. As the > sample size goes down, you no longer have a 2 to 4 x 10^-11 beast, it’s more > like 5X that. > > Bob > > >> On Jan 12, 2017, at 11:31 AM, Bob Stewart <b...@evoria.net> wrote: >> >> Hi Bob, >> Normally I see somewhere between 2E-11 and 4E-11 at 1S tau on my 5370A, as >> in the blue trace on the attached plot. Am I misunderstanding your meaning? >> Granted, I am clocking the 5370A with a GPSDO, but I believe I see about >> the same thing with the HP10811. This test was 1PPS vs 1PPS on two >> different units. >> The plot also has a test run by Tom, in orange, using his H Maser and a >> Timepod to show how poor the 5370 is compared to the Timepod below about 60S >> tau. These are essentially apples vs apples tests. >> >> Bob >> >> >> >> >> From: Bob Camp <kb...@n1k.org> >> To: Discussion of precise time and frequency measurement >> <time-nuts@febo.com> >> Sent: Thursday, January 12, 2017 8:27 AM >> Subject: Re: [time-nuts] General questions about making measurements with >> time interval counter. >> >> Hi >> >> There are a number of ways to improve the resolution (and accuracy) of your >> data without spending >> big piles of cash. They have been discussed here on the list many times over >> the last few years. >> What I’m suggesting is that you dig into that ahead of taking data. You will >> dive into it eventually as you >> look more and more at devices that are locked to some sort of stable >> reference internally. >> >> Ideally you would like a device with a floor 5X to 10X better than what you >> are measuring. For ADEV style >> data, the 5370 is a 1x10^-10 sort of device single shot (so 1x10^-9 is the >> limit at 10:1). With a lot of averaging >> (which is not something you do with ADEV) you can get about 5X better than >> that as a floor. In either case, it is getting in the way of any >> readings that are much below 1x10^-9 at one second. A low cost XO can hit >> that level of performance. >> >> Bob >> >> >> <ADEV.png>_______________________________________________ >> 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. > > > <ADEVs.png><Phase.png>_______________________________________________ > 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 To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
