[time-nuts] Question about effect of sample interval on ADEV

Tom Van Baak tvb at LeapSecond.com
Tue Jul 9 00:30:50 UTC 2013


FYI: I tend to record all serial (RS232/GPIB/USB/LAN) data from counters, analyzers, receivers, environmental sensors with a precision MJD prefix. This allows both tight correlation among different instruments in the lab and also allows ADEV-like tools to estimate, and then gradually refine to high levels of precision, the actual data rate, during data collection. Yes, it adds a few extra bytes, but it can be valuable information sometimes and storage is cheaper than it was a decade ago.

/tvb

----- Original Message ----- 
From: "John Miles" <john at miles.io>
To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
Sent: Monday, July 08, 2013 2:17 PM
Subject: Re: [time-nuts] Question about effect of sample interval on ADEV


> No prob!  It's a complicated business.
> 
> -- john, KE5FX
> Miles Design LLC
> 
> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Robert Darby
>> Sent: Monday, July 08, 2013 5:48 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Question about effect of sample interval on ADEV
>> 
>> John,
>> 
>> After a night's sleep and a rereading of  your post I finally realized
>> what I was doing wrong.  I did not understand the the role of the
>> sampling interval setting and the display rate setting on the 5370.
>> When I follow the process below the results are totally consistent.
>> 
>> Sorry to taken your time and thanks all for your help.  Now to find the
>> original issue.....
>> 
>> Bob Darby
>> 
>> On 7/7/2013 8:57 PM, John Miles wrote:
>> > So the only difference between the test setups is the setting of the
>> > Display Rate control on the 5370, correct? You're allowing TimeLab to
>> > estimate the sample rate automatically, and giving it enough time to
>> > converge on a stable reading before hitting 'Start Measurement'?
>> > You're correct in that changing the real-world sample rate should
>> > yield results that are identical (or at least very similar) to
>> > resampling the phase data after the fact. In frequency mode, dead time
>> > between readings would make that an iffy proposition, but for data
>> > taken in TI mode the outcomes should be close. -- john, KE5FX Miles
>> > Design LLC
>> 





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