[time-nuts] TimeLab

Hal Murray hmurray at megapathdsl.net
Mon Oct 10 00:16:45 EDT 2016


tvb at LeapSecond.com said:
> No, not narrow pulses. Do not use the trailing edge of a 1PPS. This is more
> about 1 Hz from a stable frequency standard, not 1PPS from a noisy GPS
> receiver. 

I think we are discussing two different things.

Your setup would work if the pulse-under-test is drifting.  Mine won't.

I was trying to inquire about the stability of the pulse width.  If your 
reference pulse is known to be stable and is wide enough, you can use the 
trailing edge to stop a TIC and the normal/leading edge of your 
to-be-measured pulse to start the TIC.  That's just a hack to displace an 
edge far enough so that there is no sign reversal on the time between two 
pulses when one of them wanders around.  It doesn't require any extra gear.

Your suggestion requires a wide pulse and some software.  None of my GPSDOs 
have a wide pulse.  I assume one of your PIC options would do what is needed 
if run from the 10 MHz which my GPSDOs do put out.  (Do you have a 15 MHz 
option?)



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