[time-nuts] Cheap stable frequency sources

Hal Murray hmurray at megapathdsl.net
Thu Sep 23 04:27:53 UTC 2010

> You’d probably want to inhibit the circuit during the two periods between
> dawn and dusk to avoid what I believe is called the diurineal (sp) shift.
> In that small amount of time the Rb oscillator shouldn’t drift out of spec. 


I think it's more complicated than that.  The problem is that the ionosphere 
layer changes height from day to night.  While it's changing, there is a 
slight Doppler shift.  If all you want is frequency, both day and night are 

The catch is that there will be a phase/time shift between day and night.  So 
if you mask out a few hours around sunrise and sunset, you will be modulating 
your oscillator with a square wave with a frequency of 1 cycle per day.

If you can coast for 24 hours, it might work to only unmask during the night 
or during the day.  (whichever works better at your location)

Good info here:

These are my opinions, not necessarily my employer's.  I hate spam.

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