Although, as I read the paper again, it is possible that the frequency bias in the 10 second CONT-mode measurements could come from this effect.
That particular series (and only that) was collected using TimeLab. I supplied them with a custom compiled driver that does not use repeated calls to READ - and therefore does not exhibit this particular bias. I always assumed that this driver was used to collect that series, but the paper does not state this explicitly so I might be wrong. The bias I am pointing to is gate time dependant, the bias getting smaller with longer gate times. It is possible it will be at the E-15 level at 10 second gatetime, like in the paper. Ole On Fri, Nov 24, 2017 at 2:45 PM, Magnus Danielson < mag...@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@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@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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.