[time-nuts] GPS receiver time message offsets to 1PPS

Hal Murray hmurray at megapathdsl.net
Tue Jul 26 07:51:27 UTC 2016


holrum at hotmail.com said:
> I originally thought the SCPI receivers would be right on time due to
> my original measurements of their message jitter,  but when I started
> measureing the actual message arrival times... surprise, surprise, surprise! 
> I think the issue is due to the fact that they use Motorola receivers and
> those ramp the time the message comes out (1 msec per second). 

One of us is confused.  Do you have a scope?

I have 2 different programs.  Both agree that the arrival time is stable.

Attached is a histogram.  There is no PPS on the system collecting the data 
so there is 200 micro-sec peak-peak of noise on the reference clock.  But 
most of that is due to daily temperature swings and I don't have enough data 
to cover that yet.

If you don't find anything, I'll clean up a program so you can run it on your 
hardware.

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