Standalone PC Clock Sync - NTP

This is a discussion on Standalone PC Clock Sync - NTP ; I have a PC running Windows that gets disconnected from the network for up to an hour. I am using NTP to sync the clock while it is connected but when disconnected the clock drifts quite a bit. Does anyone ...

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Thread: Standalone PC Clock Sync

  1. Standalone PC Clock Sync

    I have a PC running Windows that gets disconnected from the network for
    up to an hour. I am using NTP to sync the clock while it is connected
    but when disconnected the clock drifts quite a bit. Does anyone have
    any suggestions for how I can maintain the timing in this scenario?



    Also, I have been looking for a PCI card that would give me better clock
    accuracy than the standard Windows clock. Sub-millisecond accuracy
    using NTP is the objective.





    Thanks,



    David Russell

  2. Re: Standalone PC Clock Sync

    In article ,
    David.Russell@dowjones.com (Russell, David) wrote:

    > I have a PC running Windows that gets disconnected from the network for
    > up to an hour. I am using NTP to sync the clock while it is connected
    > but when disconnected the clock drifts quite a bit. Does anyone have


    Once stabilised, ntpd should not drift significantly in one hour, assuming
    you haven't meddled with maxpoll, which, unfortunately, many people do.
    It will typically be polling every 20 minutes and an hour drop out won't
    even cause it to declare the sever down.

    Either you haven't told us the whole story, e.g. it may be a lap top that
    goes into a different power management state for that less than an hour,
    or you need to find out why you are not reaching a poll interval of
    1024 seconds when you are connected.

    PS your subject is confusing as the most common question from Windows
    users is about running with no real servers, which might also be considered
    standalone.

  3. Re: Standalone PC Clock Sync

    Russell, David wrote:
    > I have a PC running Windows that gets disconnected from the network for
    > up to an hour. I am using NTP to sync the clock while it is connected
    > but when disconnected the clock drifts quite a bit. Does anyone have
    > any suggestions for how I can maintain the timing in this scenario?
    >
    >
    >
    > Also, I have been looking for a PCI card that would give me better clock
    > accuracy than the standard Windows clock. Sub-millisecond accuracy
    > using NTP is the objective.
    >
    >
    >
    >
    >
    > Thanks,
    >
    >
    >
    > David Russell


    You can purchase a PCI card from either Meinberg Funkurhren or
    Symmetricomm. Expect to pay $1100 US and up, especially up! These are
    equipped with a precision crystal oscillator, optionally an Oven
    Controlled Crystal Oscillator (OCXO). They can be equipped with an
    optional GPS receiver. The Symmetricomm products are the BC635PCI
    and the BC637PCI (with built in GPS). I don't recall what Meinberg
    calls their product.

    With GPS input, these products can give you sub-microsecond accuracy.
    Even without the GPS input they can keep time as accurately as you can
    set the clock. They are overkill for most people.

    An inexpensive GPS receiver such as the Garmin GPS18LVC ca. $100 US can
    do much the same for you if you can site an antenna with an unobstructed
    view of the sky. The principal difference is the "holdover" capability
    of Symmetricom and Meinberg products; though they are not, in
    themselves, primary standards they are extremely good clocks and will
    exhibit extremely low drift.


  4. Re: Standalone PC Clock Sync

    Russell, David wrote:
    > I have a PC running Windows that gets disconnected from the network for
    > up to an hour. I am using NTP to sync the clock while it is connected
    > but when disconnected the clock drifts quite a bit. Does anyone have
    > any suggestions for how I can maintain the timing in this scenario?
    >
    > Also, I have been looking for a PCI card that would give me better clock
    > accuracy than the standard Windows clock. Sub-millisecond accuracy
    > using NTP is the objective.


    Let's start with the basics. What version of NTP are you running and
    what operating system? What's in the drift file and are there any errors
    in the application event log?

    Danny

  5. Re: Standalone PC Clock Sync

    The PC is running XP and the Greyware Domain Time II NTP client.

    I'll track down the drift file info. Do you think that it should be
    possible to maintain the clock accuracy while the PC is unable to
    receive any NTP packets?


    David

    -----Original Message-----
    From: Danny Mayer [mailto:mayer@ntp.isc.org]
    Sent: Sunday, November 04, 2007 8:24 PM
    To: Russell, David
    Cc: questions@lists.ntp.org
    Subject: Re: Standalone PC Clock Sync

    Russell, David wrote:
    > I have a PC running Windows that gets disconnected from the network

    for
    > up to an hour. I am using NTP to sync the clock while it is connected
    > but when disconnected the clock drifts quite a bit. Does anyone have
    > any suggestions for how I can maintain the timing in this scenario?
    >
    > Also, I have been looking for a PCI card that would give me better

    clock
    > accuracy than the standard Windows clock. Sub-millisecond accuracy
    > using NTP is the objective.


    Let's start with the basics. What version of NTP are you running and
    what operating system? What's in the drift file and are there any errors
    in the application event log?

    Danny

  6. Re: Standalone PC Clock Sync

    Russell, David wrote:
    > The PC is running XP and the Greyware Domain Time II NTP client.
    >


    I've never heard of it. I managed to track this down. I can't tell a
    great deal from what they say since they are short on real technical
    details. Some of their charts are incorrect since not only does NTP run
    on Windows servers of all flavors, it runs as a service. Not only that
    the reference implementation is free and Meinberg has done an excellent
    job of packaging it. They also provide a free monitoring utility.

    There are some things that the installer does not do, like install
    itself on remote systems, though it's possible to script that. It also
    does not run on win9x machines. It's not worth the effort.

    > I'll track down the drift file info. Do you think that it should be
    > possible to maintain the clock accuracy while the PC is unable to
    > receive any NTP packets?
    >


    Don't bother looking for a drift file. I thought you were running the
    reference implementation of NTP.

    My guess is that it is using SNTP rather than NTP so it's not really
    disciplining the clock. The reference implementation of NTP not only
    ensures that the time is correct but it also disciplines the frequency
    of the clock ticks so that the clock stays accurate even when the client
    is not connected to any servers.

    You are unlikely to have problems with the clock drifting with the
    reference implementation of NTP.

    Danny
    >
    > David


  7. Re: Standalone PC Clock Sync

    To allay suspicions that this newsgroup might be biased pro-Meinberg,
    I'll just add that PCI cards are also available from Hopf: http://ww.hopf.com/.

    Paul


  8. Re: Standalone PC Clock Sync

    Paul.Croome@softwareag.com wrote:
    > To allay suspicions that this newsgroup might be biased pro-Meinberg,
    > I'll just add that PCI cards are also available from Hopf: http://ww.hopf.com/.
    >
    > Paul


    We try not to be biased about it. There are indeed many vendors who sell
    refclock modules and are much cheaper than Meinberg. It depends on your
    requirements what you should get and starting from no requirements
    anything will do. BTW I assume that the URL you meant
    http://www.hopf.com/ since you were missing a w!

    Danny

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