Time ticks on a PC, and making them accurate

From: Anthony G. Atkielski (anthony@atkielski.com)
Date: Sat Nov 19 2011 - 10:29:19 UTC

  • Next message: Russell Eberst: "2011NOV18-19.OBS"

    Hello all,
    My attention was drawn to this list by Jay Respler. I wrote the tiny
    WWV32 program that plays time ticks on the PC. I have some additional
    details about this program, plus some information on how to get your
    PC time accurate (if this has not been previously covered).
    The WWV32 program is inspired by WWV's broadcasts, and plays silence
    interrupted by beeps each second. A longer beep marks every ninth
    second, and a special pattern of beeps marks each minute. Assuming you
    already know the time, the beeps can help you keep track of the
    passing minutes and seconds.
    Another program available on the same page, which I just put out there
    in beta version, is WWV3. This program plays audio tones that are
    identical to those of the real WWV broadcasts. If you want
    authenticity, this program is useful. However, since the WWV tones are
    continuous tones with ticks interrupting them, and with fewer markers
    for the minute, you might find this program more annoying than WWV32,
    depending on your preferences. I hope to add audio announcements of
    the time at some point, once I can find or make good voice recordings
    (my voice is ill-suited to this).
    Another thing that might be useful is optimizing your PC for accurate
    time. If you are running Windows XP or a later version of Windows, the
    system already synchronizes your PC over the Internet with central
    time servers, using a protocol called NTP. NTP is a very accurate way
    to synchronize time of day across all the computers in a network, and
    has been in use for ages on servers to keep all machines within
    milliseconds or even microseconds of each other.
    The Windows XP built-in NTP function version is capable of this
    accuracy, too, but by default, Windows only synchronizes the time once
    a week. And most PC clocks are off by many seconds a day, so a
    once-a-week synchronization makes the PC useless for time checks that
    have to have sub-second accuracy. Fortunately, there's a parameter you
    can change in your PC that will vastly improve this.  Here's a
    Microsoft page that describes the parameters:
    For purposes of accuracy, you really only need to change the
    SpecialPollInterval parameter mentioned on the page above. By default,
    this parameter, which controls how often the PC synchronizes, is set
    to one week. However, you can set it to, say, one hour, in order to
    get your PC to stay accurate to within a fraction of a second. A value
    of 3600 (one hour, in seconds) can work well. With this parameter
    changed, your computer should be more than accurate enough to produce
    ticks that are accurate to within a small fraction of a second.
    There are also other parameters you can change, such as the servers
    from which your PC gets the time, but those aren't as important as
    changing SpecialPollInterval.
    You need a continuous Internet connection to make this change (like
    ADSL, cable, etc.). If you still use dial-up to reach the Internet,
    this won't help.
    You can double-click on the time in the taskbar of your machine and
    select the Internet Time tab to see the last time your machine
    synchronized, and the next scheduled synchronization. You can also
    change the time server if you wish (the NIST and some other
    organizations have free time servers you can access).
    With this optimization carried out, you don't need any special
    software to maintain extremely accurate time of day on your PC.
    Seesat-l mailing list

    This archive was generated by hypermail 2b29 : Sat Nov 19 2011 - 10:30:26 UTC