[time-nuts] need recomendation for a portable 10mhz reference oscilator

SAIDJACK at aol.com SAIDJACK at aol.com
Wed Dec 12 03:06:54 UTC 2007


 
In a message dated 12/11/2007 13:14:14 Pacific Standard Time,  
bruce.griffiths at xtra.co.nz writes:

>Why  not lock it to a GPS timing receiver output when its at home, and
>allow  the controller to learn the aging and tempco characteristics etc
>of the  oscillator being disciplined and use this information to correct
>for  temperature variations etc at the remote site?

>The model used can  be as complex as required to achieve the desired
>performance and a PC  can be used to derive optimum correction
>coefficients, the micro only  has to perform the simpler task of applying
>these  corrections.

>Bruce




Hi Bruce,
 
the problem with that is that OCXO retrace can really suck.
 
Some common OCXO's have parts in E-09 and even worse retrace.
 
Doing about 10 minutes of Auto Survey on an M12+ receiver and OCXO warmup,  
followed by about 20 minutes of active GPS locking will get you much better  
performance than the OCXO retrace can achieve itself.
 
It would be interesting to see if OCXO retrace is very repeatable, if yes  it 
could be compensated for of course.
 
Or leave the power on at all times after calibration.
 
bye,
Said



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