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 <[email protected]> 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 <[email protected]> > To: Discussion of precise time and frequency measurement <[email protected]> > 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 -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
