r6 - 2007-05-05 - 16:35:24 - SteveKosteckeYou are here: NTP >  Support Web > ConfiguringNTP > ConfiguringRefclocks > ConfiguringTrueTimeRefclocks
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REFACTOR See ConfiguringTrueTimeRefclocksDev for discussion of this topic.

6.1.17. Configuring TrueTime Refclocks

The TrueTime refclock driver was meant to support a variety of legacy TrueTime hardware. In addition this driver can be used as a generic "Sysplex" driver. Sysplex timecode is in the format of ddd:hh:mm:ssQ which is used in a lot of non-TrueTime hardware too.

  • 468-DC Goes Receiver (GOES doesn't transmit time anymore, though some people have a special antenna that receives GPS and converts it)
  • Omega (Supposedly no longer existant either)
  • Various GPS & IRIG receivers (XL-DC, NTS-xxx)
  • Others hardware should be supported if it auto-outputs a recognized timecode format.

The driver expects the serial port to be at 9600bps regardless of what hardware you are using, this shouldn't be a problem though. If for some reason your hardware doesn't do 9600 you can edit the refclock and recompile.

The driver attempts to step through the various supported hardware sending commands to the receiver until one happens to be recognized and it returns data that it can check for (or starts sending time).

If you are having trouble with this driver or using a non-TrueTime piece of equipment: The easiest thing to do is connect to the device (using hypterterm or minicom or whatever) and send the appropriate command for it to start sending time once a second. Then start up NTP and see if the driver works (which it should).

The most popular timecode that people will want to use this driver for is as follows:


Q is the quality indicator (usually a space to indicate everything is okay). If the quality code is a #,>,? then it will assume the device is not in sync. Depending on your hardware it could send other indicators so this could be an issue if your device looses lock often. Usually the # and ? are common for most devices I have seen though.

Related Topics: TrueTimeRefclockUsers

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