[time-nuts] Accurate 1 pps signals
Martyn Smith
martyn at ptsyst.com
Tue Aug 18 19:29:29 UTC 2009
Hello,
I am trying to achieve accuracy with two frequency standards disciplined to
GPS.
I am trying to get their 1 pps outputs close to each other as possible.
The idea being you put each unit in a different part of the world and the 1
pps outputs are sycronised.
So far I have two units (GPS10RBN) on their own antennas. The antennas are
seeing slightly different parts of the sky. The antennas have different
length cables but I have equalised the delays by entering a GPS delay into
one of the GPS receivers inside the GPS10RBN.
I plot the rising edge of the 1 pp signals (derived directly from the
rubidium) using my SR620 in time interval mode. The sample time is 1
second?
My results are that they are within plus/minus 8.5 ns. This is over a 24
hour period. I'm sure they will still this close, I just haven't had enough
time to make longer measurements.
This is a peak to peak measurment with no sampling.
Does anyone know a way of getting better results? My target is actually 10
ns, so I am meeting that, but just wondered what anyone else has achieved.
Regards
Martyn
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