[time-nuts] How To Measure Long Term Phase Stability Of An Oscillator

Magnus Danielson magnus at rubidium.dyndns.org
Sun Sep 22 11:47:07 UTC 2013


On 09/22/2013 01:30 PM, W3KL wrote:
> How does one make a measurement of the phase stability of an oscillator over
> a time period much larger than the oscillator period?  For example, I have
> an oscillator with a frequency of 4 MHz and I want to measure the phase
> drift of the RF between a given point in time and then a time 4 seconds
> later.  I want to make a measurement that has a precision of 0.1 degree or
> better.
You want to measure a drift of 4/(4E6*3600) = 278 ps. You systematic
frequency error can be at maximum 1.39E-10 relative, For your noise side
look at TDEV at tau of 4 s, multiply that number by at least three and
it should when added with peak frequency error be below 278 ps.

Cheers,
Magnus



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