[time-nuts] 10MHz Rubidium reference source for frequency counter
Charles Steinmetz
csteinmetz at yandex.com
Sun Nov 2 20:19:02 UTC 2014
Karen wrote:
>Mode has been switch from Frequency to TI - result is much better
>now. It was the main improvement in my measurement.
Your plot shows all traces starting at ~1e-9 at 0.1 second and
dropping almost ruler-straight at 10x per decade.
Any real crystal oscillator will flatten out somewhere between 1
second and 100 seconds, typically first to ~square root of 10 per
decade, then to 0 per decade, and generally will be on the way back
up before 1000 seconds and before getting to 1e-13. (For examples,
see <http://leapsecond.com/pages/z3801a-osc/>.)
Also, the fact that there is so little difference between the test
oscillators is too unusual to be a coincidence.
It does not appear that you are actually measuring the ADEV of the
oscillators you are testing -- you seem to be measuring your test setup.
Best regards,
Charles
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