FreeBSD 6.2 with Spectracom 9283 GPS units? - NTP

This is a discussion on FreeBSD 6.2 with Spectracom 9283 GPS units? - NTP ; I need to syncronize several FreeBSD boxes off a Spectracom NetClock 9283 unit. For reasons that I can't elaborate here, I can only use the RS485 and PPS signals off the 9283, not their built-in NTP servers. So far, it ...

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Thread: FreeBSD 6.2 with Spectracom 9283 GPS units?

  1. FreeBSD 6.2 with Spectracom 9283 GPS units?

    I need to syncronize several FreeBSD boxes off a Spectracom NetClock
    9283 unit. For reasons that I can't elaborate here, I can only use the
    RS485 and PPS signals off the 9283, not their built-in NTP servers.

    So far, it looks like my best bet is to run STP and 50Ohm coax wiring
    from the Spectracom to the FreeBSD boxes, get RS485-RS232 converters,
    and using some leftover BNC T connectors from the days of thinlan
    connect the PPS signal that's coming down the coax to the signal ground
    and DCD pins of the RS232 connector.

    Questions:

    1. Has anyone on the list actually interfaced a 9283 to a unix box this
    way? ANything I should watch out for?

    2. Does there already exist a box that will do all this, so I don't have
    to put it together myself?

    Thanks,

    /ji

  2. Re: FreeBSD 6.2 with Spectracom 9283 GPS units?

    John,

    We have been running several Spectracom GPS and WWVB receivers here over
    the last 20 years. So far as I know, these and later receivers use the
    same suite of serial timecode formats supported by the WWVB driver. We
    use the PPS signal on the DCD line for Solaris machines and the parallel
    port for the FreeBSD machines with excellent results. The PPS signal
    from the Spectracom receivers is TTL level on BNC connectors, which are
    definitely not legacy type. The beauty of the parallel port is that it
    requires no level converter.

    If you daisy chain the PPS signal to a number of machines separated by
    more than a few feet, you should terminate the last machine with a
    resister matched to the coax impedance - 50 or 75 ohms.

    Dave

    John Ioannidis wrote:
    > I need to syncronize several FreeBSD boxes off a Spectracom NetClock
    > 9283 unit. For reasons that I can't elaborate here, I can only use the
    > RS485 and PPS signals off the 9283, not their built-in NTP servers.
    >
    > So far, it looks like my best bet is to run STP and 50Ohm coax wiring
    > from the Spectracom to the FreeBSD boxes, get RS485-RS232 converters,
    > and using some leftover BNC T connectors from the days of thinlan
    > connect the PPS signal that's coming down the coax to the signal ground
    > and DCD pins of the RS232 connector.
    >
    > Questions:
    >
    > 1. Has anyone on the list actually interfaced a 9283 to a unix box this
    > way? ANything I should watch out for?
    >
    > 2. Does there already exist a box that will do all this, so I don't have
    > to put it together myself?
    >
    > Thanks,
    >
    > /ji


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