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Re: [gpsd-dev] Direct GPS support in ntpd makes me nervous


From: Gary E. Miller
Subject: Re: [gpsd-dev] Direct GPS support in ntpd makes me nervous
Date: Tue, 22 Oct 2013 10:46:43 -0700

Yo Eric!

On Tue, 22 Oct 2013 11:14:21 -0400
"Eric S. Raymond" <address@hidden> wrote:

> > Type 20 is Generic NMEA, but there are others (Jupiter, Oncore,
> > Palisade, etc.).
> 
> Heads up, Harlan. You need to hear this.
> 
> Learning that there is direct GPS support in ntpd makes me nervous.
> I recommend you take a good hard look at *removing* it.

I think this is a tad harsh. ntpd assumes the daemon is network
connected and so has a number of other sources to get data like the
current century and the leap seconds.  It also has no need for position,
velocity, error estimates, sky view, etc.  All ntpd really needs is the
top of the second from the PPS.  Then it takes that data from the
multiple sources, applies voting rules and comes up with a best guess.

If it misses some GPS time thing then the voting will ignore the GPS
data until later it seems valid.

So if time is all you want, ntpd is the way to go.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588

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