r3 - 2004-09-12 - 05:58:00 - HarlanStennYou are here: NTP >  Support Web > ConfiguringNTP > ConfiguringRefclocks > ConfiguringMotorolaOncoreRefclocks
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" graphics="on"}% REFACTOR See ConfiguringMotorolaOncoreRefclocksDev for discussion of this topic.

6.1.11. Configuring Motorola ONCORE Refclocks

I try to summarize the necessary steps to set up an M12+T for precision timing using:

  1. Set Position-Hold position, either:
    • Manually: If the Antenna position is known the user can specify the coordinates by the @@As command.
    • Using Autosurvey: The mode 3 in @@Gd command will automatically average 10,000 position fixes and then force the receiver into Postion-Hold. This operation can take some hours. To check if the receiver is in Position-Hold mode, the bit 4 ("AutoSurvey Mode" of the @@Ha or @@Hb command has to be set 00, during averaging has value 01).
  2. Set Cable delay with command @@Az: In our case the a cable of 5 meters means a delay of 25ns. After sending this command we guess the time included in the @@Hb answer is time automatic corrected of cable delay.
  3. Set the Timing Parameters by the commands:
    • @@Gf: This message is used to set the T-RAIM alarm limit (between 300 and 1,000,000ns).
    • @@Ge: This message is used to turn the T-RAIM function on.
    • @@Hn: The @@Hn T-RAIM Status Message to get status strings that alert to any alarm conditions.

Richard Gilbert says:

Assuming that your version of NTP was built with the ONCORE refclock driver, you should be able to connect your Motorola Oncore GT+ to a serial port and configure it as directed by the documentation for that version! I've only configured an Oncore on ntpd 4.2.0 which requires two links:

  • /dev/oncore.pps.0
  • /dev/oncore.serial.0

pointing to your serial port.

Next you need /etc/ntp.oncore0 which is configuration file that looks something like this:

# /etc/ntp.oncore0
# Reference Clock configuration for Motorola Oncore M12
# Five Choices for MODE
#    (0) ONCORE is preinitialized, don't do anything to change it.
#          nb, DON'T set 0D mode, DON'T set Delay, position...
#    (1) NO RESET, Read Position, delays from data file, lock it in, go to 0D mode.
#    (2) NO RESET, Read Delays from data file, do SITE SURVEY to get position,
#                  lock this in, go to 0D mode.
#    (3) HARD RESET, Read Position, delays from data file, lock it in, go to 0D mode.
#    (4) HARD RESET, Read Delays from data file, do SITE SURVEY to get position,
#     NB. If a POSITION is specified in the config file with mode=(2,4) 
#         then this position is set as the INITIAL position of the ONCORE.
#         This can reduce the time to first fix.
LAT 39 45.3753          # Positive is North.
LONG -75 04.27187       # Negative is West
HTGPS 18.28 M           # Height in meters.
SHMEM  /var/log/ntpstats/ONCORE.0
TRAIM YES               # May need this if antenna position is suboptimal.

Finally, you need to add a server statement in /etc/ntp.conf:

# Reference Clock (Motorola Oncore M12)
server prefer

All this stuff is, AFAIK, version specific. What I have shown here is working on a Sun Ultra 10 running Solaris 8.

Your mileage may vary.


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