[time-nuts] Centering ocxo
hmurray at megapathdsl.net
Wed Oct 3 00:54:41 EDT 2012
docdailey at gmail.com said:
> I am ok for awhile but how do you center the efc of an ocxo? I understand
> there is something (screw) to adjust the ocxo so it is approximately on freq
> with 2.5v efc.
> Specific oscillator datum-1111c. I have he datasheet but doesn't say "coarse
> frequency adjust this screw" or some such.
There may not be a coarse adjustment. If the tuning range is big enough to
cover the aging over your design life, you don't need one.
There is a tradeoff between adjustment range and the number of bits you need
in a DAC to get a required accuracy.
Suppose I have an adjustment range of 1 Hz (peak to peak) on a 10 MHz
oscillator. That's 1 part is 10^7. If I have a 10 bit DAC, I can adjust to
1 part is 10^10. A 20 bit DAC can get to 1 part is 10^13.
But if the tuning range is 10 Hz, the same 20 bit DAC setup only gets you to
1 part is 10^12.
These are my opinions. I hate spam.
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