Hi Jeremy, > the 5360A "Computing Pig" > I've never figured out the difference.
See the top of page 11 of http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1971-11.pdf where it says: "Fractional frequency deviation is the term used to describe the frequency instabilities of a source in the time domain. It has been shown [4] [5] that a meaningful quantitative measure of fractional frequency deviation is given by the Allan variance:" ... 4. D. W. Allan, 'Statistics of Atomic Frequency Stan dards,' IEEE Proceedings, Vol. 54, No. 2, 1966. 5. NBS Technical Note 394, 'Characterization of Fre quency Stability.' So that's the same as the definition given, for example, here: http://www.wriley.com/paper2ht.htm#Allan_Variance There is one source of confusion: ADEV (Allan deviation) is the square root of AVAR (Allan variance). We almost always calculate and plot AVAR. The other confusion is Allan (it's not Allen). ---- The 5360A is still a favorite of us old-tyme collectors. Lots of information on the old thread (you're in it): "HP 5360A History?" https://www.febo.com/pipermail/time-nuts/2016-April/097227.html The 5360A source code to the ADEV program is here: http://leapsecond.com/hpj/v22n4/v22n4p10.jpg /tvb ----- Original Message ----- From: "Jeremy Nichols" <jn6...@gmail.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Monday, January 09, 2017 2:09 PM Subject: Re: [time-nuts] σ vs s in ADEV In the late 1960s, Hewlett-Packard engineers worked up a program to have the 5360A "Computing Pig" (so-called from its weight, 55 pounds without plug-ins) compute a "fractional frequency standard deviation." It appears to be similar to the Allen Deviation; I've never figured out the difference and would appreciate hearing from someone with stronger math skills who can explain the two. Jeremy _______________________________________________ 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.
