[ntp:questions] ref clock for network POP locations

Jeff W. Boote boote at internet2.edu
Tue Sep 26 19:56:09 UTC 2006

I have some network locations where I have no way to access GPS or CDMA. But, I 
would still like to have a very accurate time source. (I would like 
sub-microsecond accuracy from NTPD if I can get it.) These locations are in 
telco-hotels, so they are typically very well shielded making any broadcast 
technology unworkable. (We are not using sonet - so getting time from there is 
also not an option.)

I was thinking that it might be possible to get an oscillator to provide a PPS 
signal, and then use a very well connected (possibly even a dedicated network 
link with no router/switch) network peer as the preferred peer. Is this a 
reasonable solution? Can anyone suggest anything better?

The PPS would need to be calibrated... Is the normal ntp calibration reasonable 
for this? I would guess it depends on the oscillator...

If this is a reasonable solution, does anyone have recommendations for 
oscillators? Most of the ones I have seen want a reference source of their own. 
This of course does not work in my case...


P.S. I will happily add information to the wiki on this after figuring out how 
to do it. (If?)

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