[time-nuts] Getting NTP/Linux to work with GPS-DO?

Stanley Reynolds stanley_reynolds at yahoo.com
Mon Oct 20 20:35:20 UTC 2008


The two things that come to mind are is the pulse wide enough and is it the correct polarity. Polarity wrong would only add delay but the pulse width would cause the PC to not see it.

Check these links:

http://www.tapr.org/kits_fatpps.html

http://www.wraith.sf.ca.us/ntp/#gps-receiver


 


----- Original Message ----
From: Bruce Taylor <bruce.tayloriv at gmail.com>
To: time-nuts at febo.com
Sent: Monday, October 20, 2008 3:09:07 PM
Subject: [time-nuts] Getting NTP/Linux to work with GPS-DO?

Folks,

  Has anyone gotten a Jackson Labs 'Fury' gps-do to work as a time/pps
source for Linux?

  Our lab is looking to use both the stable 10MHz clock for various
LOs on a radio-telescope, and also get reasonably tight timing for a
software correllator to use in discriminating pulsar signals.

  Our Linux guy has lost most of his hair out trying to get the NTP
daemon to receive the PPS signal and thus get NTP to see the GPS-DO as
a stratum 0 source.

  Our configuration is: vanilla Linux from kernel.org (version 2.6.23)
running on an intel platform.  We've applied the LinuxPPS kernel
patch, and we're feeding the serial port with the Fury in NMEA mode.
We made the required internal mod on the Fury to feed the PPS signal
out on the serial port, and can see it blinking using a scope.

  Apologies if my description is vague, as I'm just getting into the
fun and joy of kernel hacking :-)

  Many thanks for any advice,

  - Bruce Taylor

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