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

Bob Camp lists at rtty.us
Sun Sep 22 07:56:52 EDT 2013


Hi

I think he needs 16X better than that (0.1 degrees in 4 seconds) so it's 1/(4*4e6*3600).

That's right around 2x10^-11, so you would need a system that's good to maybe 2x10^-12 to do the trick. The easy approach is to build several of the same oscillator and compare them to each other. The assumption would be that the drift will be random over the 4 second period. 

Bob

On Sep 22, 2013, at 7:47 AM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> 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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