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

[Bob Camp]

Hi

In this case it would need to be a really good oscillator at or very near 4 MHz. That's not a real common frequency. Yes you could double 10 MHz and then divide by 5, but that  has it's own issues…..

Bob

On Sep 22, 2013, at 6:15 PM, Chris Albertson <albertson.chris at gmail.com> wrote:

> On Sun, Sep 22, 2013 at 4:30 AM, W3KL <w3kl at w3kl.com> 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.
> 
> The simplest way to first to get a very much better oscillator than
> the one you need to test.  You need a "refference".   Then you "add
> them" and if there is any deference at all you will get a beat
> frequency
> 
> If the two are "close" the beat will be very slow, slow enough you can
> measure the period with a wrst watch.   Put the two on a daul channel
> scope nd watch.
> 
> More sofesticaed method is to use a transformer to add the two signals
> then feed the sun into a computer's audio input or otherwise record
> the beat frequency.   You can do an FFT on the recording.
> 
> I sure others will have even better methods but my point is that
> simple technique can work, provided you have a really god reference
> oscillator.
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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