[time-nuts] LTE-Lite module
csteinmetz at yandex.com
Sun Oct 19 14:39:50 UTC 2014
> >zeroes). That would need to be done by changing the PLL parameters
> >internal to the LTE-Lite, which are inaccessible. Without such
> >reprogramming, the LTE-Light can never get the best out of an OCXO.
>It certainly can and it's not even hard:
>Configure the LTE to emit a suitable frequency relative to the
>OCXO and use an analog PLL to steer the OCXO's EFC.
Any worthwhile OCXO will need a loop with a time constant on the
order of hundreds of seconds (a corner frequency on the order of uHz)
to get the most out of it as a GPSDO. As has been discussed on the
list many times, there is simply no practicable way to design an
analog loop with such a long time constant. So the person designing
the PLL must be able to design and build an all-digital PLL, or
settle for a loop that crosses over to the GPS several decades too
early (which is certainly not getting the most out of the OCXO).
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