John,
Your description of the 1 PPS signal (small amplitude and bipolar) sounds
like you are either looking at to wrong pin or there is a broken wire
somewhere. I see this sort of signal when probing with a scope and happen
to be looking at an adjacent wire that is not connected to anything. The
capacitance between the wires will cause you to see a signal that looks
like what you described. The 1 PPS signal is typically a pulse just a few
microseconds in duration but should not be bipolar.
A bad scope probe will also cause the pulse to look bad.

Jim Hannon



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