[time-nuts] Absolute phase

Arthur Dent golgarfrincham at gmail.com
Fri Nov 17 17:15:38 EST 2017

I have 2 antennas mounted on opposite ends of a roof and both of them feed
commercial GPS DA/splitters and I can have as many as 10 receivers running
at one time for testing. I have also used one of the high frequency type F
TV passive splitters with one D.C. feed through and added 200-300 ohm
resistors from the other outputs to ground. All this has seemed to work
just fine but one of the older receivers apparently radiated its L.O. out
the antenna coax and would interfere with a couple of other receivers I
connected to the same DA.

Connecting one 10 Mhz references to the external trigger on my scope and
feeding 2 other GPS receivers to the input channels (all from the same
antenna DA), I can watch the slow drift at 2 ns/div with respect to the
trigger and sometimes one receiver drift one way as the other receiver
drifts in the opposite direction and sometimes they drift the same way.  The
drift is generally less than 2 ns but it is there and I assume it depends
on what the internal ‘housekeeping’ of the receiver is doing and what birds
they are using. So bottom line, they aren’t ‘locked’ to each other but are
generally close.


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