[time-nuts] Comparing PPS from 2 GPS units

Hal Murray hmurray at megapathdsl.net
Thu Dec 13 09:57:34 UTC 2012

Suppose I want to compare the PPS outputs of 2 GPS units.  The problem is 
that I don't know which one will happen first.

If I feed them into the start/stop inputs of a typical timer/freq box, I 
don't know which is which.  If I get them wrong, the answer will be 
0.999999xx seconds rather than the -0.000000xx that I want.

Is there a simple solution for this?

My straw man is to use the antenna cable delay setting to offset one of the 
PPS pulses a long way.

Plan B would be a physical delay unit.  But they are probably temperature 
sensitive, and I'm not setup to keep anything at a constant temperature.

Do any of the counter/timer boxes have a mode for this?  If so, is there a 
buzzword I've overlooked?

These are my opinions.  I hate spam.

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