[time-nuts] 53230A weirdness

[Ole Petter Ronningen]

Hi Magnus

No, I believe this is a separate issue. The data for that paper was
collected gap free, and was not affected by this particular issue.

It may be related somehow - as presented in that paper, data collected in
CONT mode shows a slope of tau^-1/2 on ADEV.

Data collected gap free in RCON-mode (i.e. not by repeated calls to READ)
shows the expected slope of Tau^-1.

The issue I point out here is that if data is collected using repeated
calls to "READ", even data collected in RCON-mode shows a slope of
tau^-1/2, in addition to a frequency bias. The magnitude of the frequency
bias is gate time dependent.

Ole

On Fri, Nov 24, 2017 at 2:45 PM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> Ole,
>
> Is this part of the behavior that the Norwegian NMI was presenting at a
> poster session at EFTF 2016 in York?
>
> I remember they borrowed your 53230A for that work.
>
> Cheers,
> Magnus
>
>
> On 11/23/2017 09:05 PM, Ole Petter Ronningen wrote:
>
>> Hi, all
>>
>> I've done some experiments on my 53230A, and I've come across an issue I
>> think could be worth knowing about.
>>
>> I have not tested this on other 53230A's - if anyone has a 53230A and some
>> spare time, I'd be grateful if someone could try to replicate.
>>
>> In a nutshell, the first frequency measurement following an INIT is
>> biased.
>> The magnitude of the bias is dependant on measurement mode (CONT/RCON),
>> and
>> gate time.
>>
>> It is worth noting that every READ implicitly calls INIT - so any software
>> collecting a time series using repeated calls to READ to fetch single
>> readings will give biased results. Not for the first sample in the series,
>> but all of them.
>>
>> As an example, the last time series I collected this way using RCON and
>> 0.1s gatetime gave an average frequency error of -5.2e-10.
>>
>> A writeup is here: http://www.efos3.com/HPAK53230A-1.html
>>
>> Best regards,
>> Ole
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>