Subject: Re: ntp and pps
To: None <>
From: Yubyub bird <>
List: current-users
Date: 05/12/2000 18:55:33
Jonathan Stone said on 2000-05-12:

> In message <>Wolfgang Rupprecht writes
> >I'm concerned that most of the advantage of using a GPS with a few
> >10's of nS of noise on it PPS line will be lost if the kernel proceeds
> >to timestamp things with only 1uS of resolution.
> It still helps. Dave Mills has nearly a decade of experience with Suns
> using microsecond-resolution clocks. Unfortunatley the MI timekeeping
> in NetBSD still uses microseconds.  I've suggested changes to that,
> but there was a lack of consensus about formats and inkernel APIs:
> other people focusing on different uses of timing proposed rather
> different APIs.

Dave Mills has done an excellent job in terms of syncronization...

     remote           local      st poll reach  delay   offset    disp
*GPS_NMEA(0)        0   64  377 0.00000  0.000044 0.00095    1   64  377 0.02582 -0.000985 0.00119

And this is without hardpps()... it works pretty darn well, and I'm
expecting that once we get over this hurdle, it will improve a small bit,
too.  This is using one of Dave Schwartz's GPSClock 200's (no affiliation
at all with him, but it's a very nice low cost unit for NTP purposes).

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