Offset in ms vs Frequency in PPM - NTP

This is a discussion on Offset in ms vs Frequency in PPM - NTP ; Hi, I would like to know if there is any relation between variations of the offset in millisecond and variations of the frequency in PPM in loopstats file ? Edouard _______________________________________________ questions mailing list questions@lists.ntp.isc.org https://lists.ntp.isc.org/mailman/listinfo/questions...

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Thread: Offset in ms vs Frequency in PPM

  1. Offset in ms vs Frequency in PPM

    Hi,

    I would like to know if there is any relation between variations of
    the offset in millisecond and variations of the frequency in PPM in
    loopstats file ?

    Edouard
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    questions@lists.ntp.isc.org
    https://lists.ntp.isc.org/mailman/listinfo/questions


  2. Re: Offset in ms vs Frequency in PPM

    edouard funke wrote:
    > Hi,
    >
    > I would like to know if there is any relation between variations of
    > the offset in millisecond and variations of the frequency in PPM in
    > loopstats file ?
    >
    > Edouard


    Yes. Offset is the difference between the OS software clock and the
    time sources. ntpd changes the frequency of that software clock to
    correct that offset, and that frequency is recorded as the PPM value in
    the loopstats file.

    The next time you drive on a highway, try to stay exactly six car
    lengths behind the car in front of you, and do it for five minutes. You
    will have a better idea of what ntpd is trying to do and how it does it.
    Think of your speed as the frequency (PPM). The distance between the
    two cars is the offset. The distance between the two cars will change
    from one second to the next second, and that change is the jitter.

    The two fields after frequency (PPM) in the loopstats file are quite
    handy, too. It is good to have low values for RMS jitter and Allan
    deviation, and ntpd has to be running for a while to achieve those values.

    Michael






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