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Re: [gpsd-dev] Clarifications needed for the time-service HOWTO


From: Eric S. Raymond
Subject: Re: [gpsd-dev] Clarifications needed for the time-service HOWTO
Date: Tue, 22 Oct 2013 20:51:23 -0400
User-agent: Mutt/1.5.21 (2010-09-15)

Greg Troxel <address@hidden>:
> >      Ordinary client computers are normally configured to get time from one
> >      or more Stratum 2 (or less commonly Stratum 3) servers. With GPSD and
> >      a suitable GPS, you can easily condition your clock to higher
> >      accuracy than typical Stratum 2; with a little effort you can do
> >      better than public Stratum 1 servers.
> 
> This sounds overblown.  Some public S1s are very good, and some aren't.

I think we cover that now.

> Another point which should be addressed is:
> 
>   ntpd has builtin support for reading some GPS timing receivers.  How
>   should one decide to use ntpd's support vs gpsd?  Does it matter?
> 
> And I'm not sure of the answer (my XL-DC machine just uses ntpd).

I'd say this: Drivers for individual, specific device types with known
sentence inventories and known cycle-start sentences are relatively
easy to get right. You know what's coming!  So if you have, like, a
Trimble Navigation Palisade (Type 29) Motorola OnCore (Type 30) or
Rockwell Jupiter GPS (Type 31) the native ntpd support is probably OK.

OTOH, I would *not* want to rely on any code but GPSD's for handling
generic unknown NMEA (Type 20).
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

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