[time-nuts] Basic question re adev measurements

Mark Spencer mspencer12345 at yahoo.ca
Mon Mar 26 21:07:30 UTC 2012


Greetings,  I was reviewing some older adev plots of mine and noticed that there may be a correlation between lower adev numbers and lower frequency off set between the reference source and the device under test.   It's my understanding that the adev calculations remove constant frequency off sets but I'm wondering in practice this degrades the the measurements. 

It occurs to me that if I am comparing two 10 MHz signals with a TIC that the available dynamic range of each measurements will be 100 ns.   Would a constant frequency off set effectively reduce the precision of the measurements by eating up some of this dynamic range ?

To put this in perspective frequency offsets of say one or two parts per trillion seem to result in better adev readings than off sets of say ten or more parts per trillion.  

Sorry if I have missed something obvious here.

Thanks in advance
Mark Spencer

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