[time-nuts] How to measure Allan Deviation?

Tom Van Baak tvb at leapsecond.com
Tue Oct 24 02:27:22 EDT 2006

> Tom
> In comparing 2 oscillators do you mean
> 1) Connecting one oscillator to the FREQ STD input at the rear of the 
> 5370A, selecting the external timebase and connecting the other 
> oscillator to the Front panel FREQ/PERIOD input and then selecting 
> frequency measurement which in effect gives the frequency ratio of the 2 
> oscillators?
> OR
> 2) Connecting the 2 oscillators to the LO and RF ports of a mixer, 
> lowpass filtering the mixer output and measuring the beat frequency?

Sorry, I should have been clearer. No, neither 1) nor 2).

Just keep it simple. Didier wants a text file of periodic
phase differences as input to any ADEV tool so set the
TIC to measure phase (or average phase). That's all.

DUT1 goes into START and DUT2 goes into STOP.

This works perfectly for kHz or 1PPS signals. It also
works pretty well for relatively short runs of 5/10 MHz
CW signals.


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