[time-nuts] GPSDO question

Bob Stewart bob at evoria.net
Sun Jul 26 00:27:16 EDT 2015


Speaking with Tom recently impressed on me just how much I don't know about what's "normal" for a GPSDO.  The options on the LEA-6T are formidable and have consequences for my GPSDO.  The question I'm struggling with now is what's normal during the survey process?  The only example of a commercial GPSDO I have is the KS-24361.  I believe it leaves the oscillator output available and both the FLL and PLL are functioning.  I've set the bit in the LEA-6T so that it doesn't emit the PPS when the time isn't valid.  So, with the other restraints I've put on it (TDOP, TAcc, etc), there's no PPS during survey.  That means there's no FLL or PLL, and the DAC is frozen, so I might as well shut off the oscillator output.  On the one hand, a survey implies the OCXO has just been turned on and all the nastiness of early retrace.  And the first several hours of these 34310-T OCXOs are horrible.  OTOH, there's the KS which, by default anyway, ignores all that and does the best it can, and does it right quickly.  I suppose it wouldn't be all that hard to add still more controls to allow it to work or not work as the user desires.  Any input on the state of the art would be appreciated.

Bob - AE6RV




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