[time-nuts] Common sky pps errors for any GPSDOs?

Matt Ettus boyscout at gmail.com
Mon Jan 5 14:31:18 EST 2009

I am working with someone who needs to have time synchronized
reception of signals in various locations which are separated by less
than 100 km.  This is a situation similar to VLBI, but since the
distances are shorter, the center frequencies are lower, and the
integration times are much shorter, we probably don't need a Hydrogen
Maser, and the application can't afford one.

The real question is whether we can get away with a GPS disciplined
OCXO or whether we would need to use a Rubidium.  Does anyone have any
data on the relative frequency and/or phase errors of the 10 MHz
reference out, and relative PPS time errors of any commonly available
GPSDOs?  Absolute error to UTC and true 10 MHz don't really matter, as
long as both devices have the same error.  Just data comparing 2 units
with antennas right next to each other would probably be fine.

The other concern, of course, is that even if both units were very
close, they will be exposed to slightly different environmental
conditions (different A/C settings, different cycling times, etc.).

Are there any good papers discussing this subject?  Any data out there?

Said -- have you measured this sort of thing on the Fury?


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