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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: |
Thu, 24 Oct 2013 08:14:10 -0400 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Gary E. Miller <address@hidden>:
> > > > What sorts of jitter are produced by different parts of the
> > > > delivery chain? What do typical magnitudes look like?
> > >
> > > The jitter from NMEA on a local GPS can be a few hundred mSec. Run
> > > a traceroute to a server and you see how bad you network can be.
> > > Cable modems could be up to 500 mSec (and they are wildly
> > > asymetric). The jitter from a local GPS s defined by the USB
> > > transfer, around 1 mSec for USB 1.1 The jitter from interrupt
> > > processing can be 100uSec and sometimes much worse on a loaded
> > > system.
> >
> > I'm not sure how to use those figure for the HOWTO. Can you
> > recommend a specific way to merge them?
>
> Maybe we just need a table of typical error sources and magnitudes? No
> need to get into the specifics.
That sounds like an excellent idea. Please make one.
--
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
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- Re: [gpsd-dev] Direct GPS support in ntpd makes me nervous, (continued)
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Eric S. Raymond, 2013/10/22
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Gary E. Miller, 2013/10/21
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Hal Murray, 2013/10/22
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Eric S. Raymond, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Gary E. Miller, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Dave Platt, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Gary E. Miller, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO,
Eric S. Raymond <=
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Hal Murray, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Eric S. Raymond, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Gary E. Miller, 2013/10/23
- Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Beat Bolli, 2013/10/23
Re: [gpsd-dev] Clarifications needed for the time-service HOWTO, Miroslav Lichvar, 2013/10/23