Re: Reference clocks questions - NTP

This is a discussion on Re: Reference clocks questions - NTP ; Jonathan Buzzard a écrit : > On Fri, 23 Jun 2006 07:12:29 -0700, Julien wrote: > > [SNIP] > > > > 2/ can you advise me some middle-range clocks (several hundred euros > > max.) working on Linux, as ...

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Thread: Re: Reference clocks questions

  1. Re: Reference clocks questions


    Jonathan Buzzard a écrit :

    > On Fri, 23 Jun 2006 07:12:29 -0700, Julien wrote:
    >
    > [SNIP]
    > >
    > > 2/ can you advise me some middle-range clocks (several hundred euros
    > > max.) working on Linux, as well as pros and cons regarding the
    > > technology (GPS, radio...) ?
    > >

    >
    > You don't say where you are in the world. However the NNTP posting IP
    > address suggests France, and you mention Euros.


    You're right, I'm in France, but the servers might be everywhere in the
    world, that's why I can't use a radio receiver as a "general" solution,
    and I'm rather looking at GPS receivers.


  2. Re: Reference clocks questions

    Julien wrote:
    []
    > You're right, I'm in France, but the servers might be everywhere in
    > the world, that's why I can't use a radio receiver as a "general"
    > solution, and I'm rather looking at GPS receivers.


    A simple GPS system is described here:

    http://www.david-taylor.myby.co.uk/n...SD-GPS-PPS.htm

    It might give you some ideas....

    David



  3. Re: Reference clocks questions

    Julien wrote:

    > Jonathan Buzzard a écrit :
    >
    >
    >>On Fri, 23 Jun 2006 07:12:29 -0700, Julien wrote:
    >>
    >>[SNIP]
    >>
    >>>2/ can you advise me some middle-range clocks (several hundred euros
    >>>max.) working on Linux, as well as pros and cons regarding the
    >>>technology (GPS, radio...) ?
    >>>

    >>
    >>You don't say where you are in the world. However the NNTP posting IP
    >>address suggests France, and you mention Euros.

    >
    >
    > You're right, I'm in France, but the servers might be everywhere in the
    > world, that's why I can't use a radio receiver as a "general" solution,
    > and I'm rather looking at GPS receivers.
    >


    The Garmin GPS18LVC is available for something like $85 US. An Oncore
    M12 timing receiver with evaluation circuit board, is available from
    http://www.synergy-gps.com/ for around $200 US. The Oncore used to be
    made by Motorola; they discontinued it and it is now made by another
    manufacturer. I have an Oncore and have found that it works very well.
    More expensive receivers are available with metal cases, switches,
    blinking lights etc. They may be worth the extra cost; the evaluation
    board I bought doesn't even have holes that would permit it to be
    mounted in a box.

    Just be certain that the receivers you buy are designed for timing
    service rather than navigation and have a Pulse per Second (PPS) output.

  4. Re: Reference clocks questions

    Richard B. Gilbert a écrit :
    >
    > The Garmin GPS18LVC is available for something like $85 US. An Oncore
    > M12 timing receiver with evaluation circuit board, is available from
    > http://www.synergy-gps.com/ for around $200 US. The Oncore used to be
    > made by Motorola; they discontinued it and it is now made by another
    > manufacturer. I have an Oncore and have found that it works very well.
    > More expensive receivers are available with metal cases, switches,
    > blinking lights etc. They may be worth the extra cost; the evaluation
    > board I bought doesn't even have holes that would permit it to be
    > mounted in a box.
    >
    > Just be certain that the receivers you buy are designed for timing
    > service rather than navigation and have a Pulse per Second (PPS) output.


    According to http://time.qnan.org/, the Garmin GPS18LVC looks fine to
    me, however I have a few concerns:

    1/ I don't want to use my soldering iron. Anyone knows a reseller that
    provide something similar to the RS-232 interface at
    http://time.qnan.org/ ?

    2/ My servers are shipped with RHEL3, which come with a 2.4
    pre-compiled Linux kernel and ntpd. I want to avoid any patching and
    compilation. What do I need to do to make ntpd read the PPS and the GPS
    time? Would the serial module (providing /dev/ttys*) and gpsd suffice?

    Thanks a lot for your help.


  5. Re: Reference clocks questions

    Julien wrote:
    > Jonathan Buzzard a écrit :
    >
    >> On Fri, 23 Jun 2006 07:12:29 -0700, Julien wrote:
    >>
    >> [SNIP]
    >>> 2/ can you advise me some middle-range clocks (several hundred euros
    >>> max.) working on Linux, as well as pros and cons regarding the
    >>> technology (GPS, radio...) ?
    >>>

    >> You don't say where you are in the world. However the NNTP posting IP
    >> address suggests France, and you mention Euros.

    >
    > You're right, I'm in France, but the servers might be everywhere in the
    > world, that's why I can't use a radio receiver as a "general" solution,
    > and I'm rather looking at GPS receivers.
    >

    In that case the Garmin GPS18LVC (note the suffix, it's important!) is
    almost certainly your best bet:

    It works everywhere you can see the sky, it costs less than $100 plus
    about an hour with a soldering iron, using USB for power (I've posted
    about this previously), and the accuracy is in the single us range.

    Terje

    --
    -
    "almost all programming can be viewed as an exercise in caching"

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