[time-nuts] 53230A TIC and TimeLab

Magnus Danielson magnus at rubidium.dyndns.org
Thu Oct 4 07:39:05 EDT 2018


Hej Ole!

On 10/4/18 11:21 AM, Ole Petter Ronningen wrote:
> On Thu, Oct 4, 2018 at 11:00 AM Magnus Danielson <magnus at rubidium.dyndns.org>
> wrote:
> 
>> Regardless, the 53230A does a filtered frequency estimation, which is
>> great for achieving high precision frequency measures quickly, but not
>> good for ADEV measures, as it introduces a bias due to the lower
>> bandwidth of the filtering as compared to the sampling interval.
>> Dead-time gaps biases also comes in.
>>
> 
> True - but be aware that the *first sample* returned from the instrument,
> when fetched using "READ", will also be biased in an absolute sense - the
> frequency reported will systematically be too high or too low (the
> magnitude and direction of the error depending primarily on gate time, from
> what I've seen).

Who-oh! OK. This means that one should intentionally let a number of
samples pass before trusting it.

It would be interesting to get some better qualifications of this.

> So even when using this mode to only look at high resolution "absolute
> frequency measurements", it is easy to get bitten if the data is collected
> using a computer.

Obviously. Good to know. Many thanks!

It is interesting to learn that we still need to handle the temperament
of instruments.

Cheers,
Magnus



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