Rasp Pi at +/- 1 us from GPS

Gary E. Miller gem at rellim.com
Fri Dec 1 02:53:22 UTC 2017

Yo MLewis!

On Sun, 26 Nov 2017 14:33:26 -0500
MLewis via devel <devel at ntpsec.org> wrote:

> I thought people working on having a Rasp Pi as a Time Server 
> would/should be aware of pps-client.

Sorry for a late reply, somehow I got unsubbed from devel@

What is the advantage of pps-client?

> My Rasp Pi 3 is running software (pps-client) that uses GPS PPS and 
> seems to be meeting the goal of maintaining system time to +/- 1 us.

Easy. gpsd and NTPsec can get you close with no special effort.  Tobreak
1 uS I have to temeprature stabilize the RasPi and GPS.

> - pps-client -v displays the "status printout", showing that in
> around ten minutes it was reporting jitter as single digit us.
> avgCorrection is typically 0.00000, -0.016667 or -0.033333,
> occasionally 0.016667 or 0.033333 us.

The granularity of the RasPi kernel clock is just under 0.200 uS.  So I
assume that is off the isntalled RTC?

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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