[time-nuts] NTP and Oncore UT+

Bob Stewart bob at evoria.net
Sat Apr 19 20:58:52 UTC 2014

I've done as much as I can do with my little Adafruit, so I guess it's time to move to a timing receiver.  I already have a UT+, so I might as well make use of it.  My thought was to use the NTP refclock driver and probably take the sawtooth from SHMEM with a simple "C" program to pass to my GPSDO.  The reference pages indicate that a PPS interface is "required".  Do I need to wire up the PPS just to get access to the sawtooth value, or can I just hook up serial access to the UT+ and use NTP as an interface to the UT+?  I have no experience with setting up a refclock driver, so any help would be appreciated.  Using NTP certainly looks a lot easier than figuring out why this UT+ doesn't always like to talk on the serial port and writing custom code to do the bits I want.  The PPS from the UT+ will, of course, be connected to my GPSDO board.

From the manual:
"The driver requires a standard PPS interface for the 
pulse-per-second output from the receiver. The serial data stream alone 
does not provide precision time stamps (0-50msec variance, according to 
the manual), whereas the PPS output is precise down to 50 nsec (1 sigma) for the VP/UT models and 25 nsec for the M12 Timing. If you do not have the PPS signal available, then you should probably be using the NMEA 
driver rather than the Oncore driver."

Bob - AE6RV

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