[time-nuts] LTE-Lite module

Charles Steinmetz csteinmetz at yandex.com
Sun Oct 19 10:39:50 EDT 2014


Poul-Henning wrote:

> >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).

Best regards,

Charles






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