Additional pps-gpio

[Gary E. Miller]

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
ppstest.

More to come.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  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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