[time-nuts] time-nuts Digest, Vol 43, Issue 35

Martyn Smith martyn at ptsyst.com
Thu Feb 14 12:36:02 EST 2008


Pete,

That's my point.

Tom has plotted Allan Variance.  I have plotted frequency accuracy.

I get similar Allan Variance results to Tom.  But if I just measure the
accuracy, e.g peak to peak frequency variations, rubidium's out- perform
OXCO's even when both are disciplined to GPS.

I hope I'm not being stupid here.

I measure frequency accuracy using my Stanford SR620 in time AB mode and
calculate the frequency error.  My accuracy floor noise is 2E-11/sec.

When measuring an OXCO based unit I often get frequency errors of plus/minus
5 milli hertz.  Rubidium units (mine and Symettricom) never has errors > 1
milli hertz.

Best Regards

Martyn






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