> In my opinion ADEV does hide changes in Frequency and we see it when > we compare ADEV plots with at the same time frequency measurements.
On purpose ADEV reduces hundreds, even hundreds of thousands of measurements to a single number. If this is what you mean by "hide" then ok. In my opinion, ADEV does not hide changes in frequency; it statistically summarizes them in a standard way. In general one should always look at phase residual or relative frequency strip charts before using ADEV. Another trick is using Stable32's DAVAR or TimeLab's multi-trace feature, both of which will expose variations in ADEV across a large data set. Or use histograms, etc. However, as you seem to imply, if you are seeing unexpected differences between frequency measurements and time (phase) measurements or between freq / time and ADEV statistics, then your measurement system(s) are broken. With only a single DUT, if different "at the same time" measurement systems report different results, then that's a smoking gun to find which measurement system(s) is failing you. > The URQ shows frequency specs 2E-12 most likely ADEV. See Table II on Page 9 of the manual [1]. /tvb [1] http://mil-spec.tpub.com/MIL-T/MIL-T-28816/MIL-T-2881600009.htm -------- Original message -------- From: Tom Van Baak <[email protected]> Date: 7/25/17 11:37 AM (GMT-05:00) To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] OCXO inside the FEI AN/URQ-23 Bert, In the early days of time-nuts the URQ-10, and especially the URQ-23, were highly sought after because of their reported stability. By now they are quite rare. Do you have one? If it's important I can dig one out from the closet and run tests for you. > "Question if it is frequency or ADEV". I'm not sure what you mean. There is no such thing as "frequency" vs. "ADEV". /tvb ----- Original Message ----- From: "Bert Kehren via time-nuts" <[email protected]> To: <[email protected]> Sent: Tuesday, July 25, 2017 7:48 AM Subject: [time-nuts] OCXO inside the FEI AN/URQ-23 > Has any one run tests of the OCXO inside the AN/URQ-23. Data in the manual > looks promising. Question if it is frequency or ADEV > Bert Kehren _______________________________________________ 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.
