[time-nuts] GPSDO control system

davidh dhooke at gmail.com
Sun Mar 23 23:48:25 EDT 2014

Hi Charles,

How do you lock your OCXO to the PRS10?



> I've lost track now of who it was, but someone asked if there was a
> better strategy than a GPS disciplined quartz oscillator or a GPS
> disciplined rubidium.  My best standard uses an SRS PRS10 rubidium
> disciplined by GPS PPS at tau = VERY long (> ~12 hours), using the
> PRS10's internal PPS locking.  The rubidium, in turn, disciplines my
> best OCXO at tau >300 seconds.  So, for tau less than ~300 seconds the
> stability is determined by the OCXO; for tau greater than ~300 seconds
> and less than ~12 hours, the stability is determined by the rubidium;
> and for tau > ~12 hours, the stability is determined by GPS.  I have
> found that this works very well.
> Note that the PRS10's digital PPS PLL has a bewildering array of
> adjustable parameters.  One can easily get lost exploring different
> combinations.  My advice is to keep it as simple as possible.
> Best regards,
> Charles

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