[time-nuts] Best counter setting for ADEV?

[Magnus Danielson]

On 10/02/2012 07:19 PM, Mark Spencer wrote:
> On a somewhat related note over the weekend I spent a few hours characterizing the performance of two of my HP5370B's for making ADEV measurements by feeding the stop and start inputs with identical 10 Mhz signals from a HP5087a distribution amp.   Not surprisingly they perform somewhat differently.    More surprisingly the results vary depending on the oscillators used for the clock source for the HP5370B's.  (I was under the impression the built in 10811's were more than adequate enough for this application.)

Did you disable the wide-band 5 MHz comb-generator of the 5370s?

I did it to mine.

Cheers,
Magnus

> I've also found that when trying to characterize the performance of an oscillator (in this case a disciplined PRS10 Rb unit) making two simultaneous measurements using different references and overlaying the results can provide some additional confidence as to their accuracy.  (I suppose if I had an H maser I probably wouldn't need to use both an OCXO and GPSDO at the same time to have confidence in the measurements (: )
>
> Looking at the phase differences in this case gives me a reasonable degree of confidence that the OCXO has not significantly drifted during the first 20,000 seconds or so and that the HP5370B's are providing valid data.
>
>
> --- On Tue, 10/2/12, time-nuts-request at febo.com<time-nuts-request at febo.com>  wrote:
>
>>
>> Message: 1
>> Date: Tue, 02 Oct 2012 13:29:11 +0200
>> From: Timeok<timeok at timeok.it>
>> To:<time-nuts at febo.com>
>> Subject: Re: [time-nuts] Best counter setting for ADEV?
>> Message-ID:<8b1628eaf26d33f1dd95b380fbed86ea at www.timeok.it>
>> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>>
>> test using HP53123A:
>> The pink line is the noise floor using the TI mode
>> The blue line is the noise floor using the Frequency mode
>> (gate 2 sec)
>> The other two line are the same oscillator, an HP105B tested
>> with both
>> the modes.
>> As you can see the range between 1 and 200 sec is "totally
>> compromised" by the system noise floor using the TI method.
>> The approximation using the freq mode can be anyway usefull
>> to make a
>> comparatinon between two source.
>> I suppose to have right measurements, without any
>> restriction we have
>> to use the Timepod or other high level instruments than this
>> kind of
>> counters.
>>
>> Luciano
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