[time-nuts] Oscilloscope-based measurements of frequency stability

Ralph Devoe rgdevoe at gmail.com
Mon Oct 1 18:05:05 EDT 2018


    This is just what I was trying to do with my paper on "sine-wave
fitting", which can be found at  arXiv:1711.07911  .  Look at the relative
phase of two frequency sources using a scope and then plot it versus time.
With a digital scope (Digilent Analog Discovery) , there's no reason to
take a screen shot, all you have to do is write the ADC outputs to files.
     The paper was written for a peer-reviewed journal, so I had to write
it in a tedious style, but it's basically the same as what is suggested
here. I used a least-square fitting routine to calculate the phase
difference in the paper, but eyeballing the phases also works.
      I've been measuring the drift and aging of a pair of HP 5065a's
versus a 5071a for the last ten months and have over 200 GB of data on
disk. I'm a lousy programmer but the Python analysis routine is short (
about 100 lines) and works fine.

Ralph


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