Additional pps-gpio

Gary E. Miller gem at
Tue Jan 30 22:51:49 UTC 2018

Yo Achim!

> I just added a u-blox 6 GPS mouse, and split the SkyTraq PPS to go
> into GPIO 4 and GPIO 18.  So three PPS on one RasPi.  I'll post
> results later today, first I finish to compiling the new kernel with
> the new multiple PPS patch.

I'm comparing SkyTraq PPS to the u-blox 6 USB PPS.  The offset between
the two varies slowly over a few minutes between 1 milli second and 0.2
millisecond.  The SkyTraq jitter is around 0.5 micro seconds, the USB
jitter around 3 micro seconds.

The USB jitter/offset is still a touch better than the time from
nearby RasPi, with serial GPS, over ethernet.

Those numbers from 'chronyc sources', double checked by eyeballing

More to come.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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