[time-nuts] OCXO Voltage Input? (Bob Camp)

Hal Murray hmurray at megapathdsl.net
Fri Sep 5 16:10:13 EDT 2014

dan at irtelemetrics.com said:
> If I had 10Mhz or some other high frequency on the EFC line, would a typical
> OCXO respond to that? 

Some VCXOs actually specify their bandwidth.  High audio is sometimes useful. 
 I haven't seen anything beyond that, but I'm just listening to discussions 
like this one.  There could well be applications that use a higher frequency.

One application is correcting for mechanical vibrations.  This is interesting 
in radar used on helicopters.  (They do Doppler filtering to remove clutter.  
The lower speed of objects that can get through the filter depends on the 
clock stability.)

PCs often FM modulate their clocks.  It's a hack to get past the FCC EMI 
requirements.  It spreads a spike in the frequency domain into a blob with a 
lower peak.  I think 30 KHz is typical.  The PCI specs were tweaked to allow 
this so they probably say something about the legal frequency limit.

PCs probably don't use expensive OCXOs, but that technology might get used in 
other applications.

How do FM modulators work?

These are my opinions.  I hate spam.

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