[time-nuts] Modified Total Deviation measurement
Dick Moore
richiem at hughes.net
Mon Jan 18 05:59:10 UTC 2010
Hi Magnus -- Any possibility that there is some math package subroutine error of some kind? In yours or theirs?
Best,
Dick Moore
>
> Message: 3
> Date: Mon, 18 Jan 2010 03:29:49 +0100
> From: Magnus Danielson <magnus at rubidium.dyndns.org>
> Subject: [time-nuts] Modified Total Deviation calculation
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Message-ID: <4B53C79D.5000403 at rubidium.dyndns.org>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Dear fellow time-nuts,
>
> In my effort to implement the suite of ADEV and friends, I have been
> implementing various forms of them along with the 1000 frequency sample
> test sequence out of NIST SP1065:
> http://tf.nist.gov/timefreq/general/pdf/2220.pdf
>
> However, I seem to be unable to perfectly match the numbers for the MTotDev.
>
> My numbers so far:
>
> m = 1 m = 10 m = 100
> Max 0.9957452943 0.7003371204 0.5489367785
> Min 0.0013717599 0.2545924150 0.4533354120
> Avg 0.4897744629 0.4897744629 0.4897744629
> Sdev 0.2884663647 0.0929635201 0.0320665644
> NAdev 0.2922318781 0.0996573606 0.0389780433
> OSAdev 0.2922318781 0.0915995342 0.0324134303
> OAdev 0.2922318781 0.0915995342 0.0324134303
> MAdev 0.2922318781 0.0617237638 0.0217092091
> Tdev 0.1687201535 0.3563623166 1.2533817739
> Hdev 0.2943883291 0.1052754194 0.0391086056
> OHdev 0.2943883291 0.0958108317 0.0323763825
> MHdev 0.2942275231 0.0621023549 0.0213087110
> TOTdev 0.2922318781 0.0913474326 0.0340653025
> MTOTdev 0.2303857898 0.0555288598 0.0195467513
>
> The MTOTdev numbers according to page 118 (of PDF, page number 108
> according to the printed pagenumbers) should be
>
> Modified Total Dev 2.418528e-01 6.499161e-02 2.287774e-02
>
> Do anyone happend to have an implementation (in source) of MTOTdev at
> hand giving the NIST SP1065 numbers?
>
> Please note that W. Riley has about the same document in his Handbook,
> and it reflects the same number. I would also suspect that a STABLE32
> run would give those numbers.
>
> I have been using both SP1065 and the original article as reference:
> http://tf.nist.gov/general/pdf/1369.pdf
>
> I've put care into ensuring that I implement it as close to these as
> possible, but with no luck in fixing the numbers.
>
> I use the averaging of the two half-ranges of the 3*m block tecnique
> rather than the minimum square estimator as recommended. The formulation
> given may seem strange, but it is the 3/2*m sample average of the
>
> f(i)=(x[n+3/2*m+i)-x[n+i])/ (3/2*m)
>
> frequency estimation where i varies from 0 to 3/2*m-1.
>
> I have already verified my test-sequence and the numbers produced by the
> other algorithms have been able to match after removing various bugs. An
> independent implementation may be a good clue.
>
> An alternative may be that the published numbers is incorrect for some
> reason, but I don't have sufficient proof for that.
>
> I have however made two different implementation variants that crunch
> out the same numbers.
>
> Cheers,
> Magnus
More information about the time-nuts
mailing list