[ntp:questions] Re: Using NTP with Trimble Acutime Synchronization Kit

Bjorn Gabrielsson bg at lysator.liu.se
Mon Dec 5 16:33:04 UTC 2005

"John Kennedy" <john.kennedyjr1 at us.army.mil> writes:

> Unfortunately, this is in an environment where we cannot add any other
> PC's.

> All of the machines are only connected via a COM port to a single
> Trimble Accutime source.

The prefered mode for refclock_palisade is using the event marker
input ("Time Trigger" in Trimblespeak). Here the computer toggle a pin
and get the exact time of the "toggle" back from the Acutime GPS.

The eventmarker mode will only work for one computer connected to one

The way most GPS get precition time to a computer is via the PPS
pulse. But I am not sure if the palisade driver has a mode for using
the PPS pulse. The comment "PPS output are not currently used by the
Palisade NTP reference clock driver." on 


suggests you are out of luck with the current code.

The machines do not have ethernet connections to each other?

Another alternative might be to try to run your serial port in
NMEA-mode and attach the PPS pulse on pin 1 (DCD).

Hmmm... are you connecting the serial output from Trimbles "little
convertion box" to multiple computers? Thats RS-232, and technicaly
only a point to point interface, not a bus interface with one sender
and many listeners. Or do the COM ports on the XPs run

> I cannot add any other devices to the environment due to
> Configuration Lockdown.  

Maybe you could give us an idea what time accuracy you need. You have
a good GPS, but your configuration and OS choice might not be

I do not use XP for much. From what I have read on this list there are
not many refclock drivers ported to the MS OSes. Is there an NMEA
driver for NTP on XP? 

You could always try to put pressure on Trimble to support the driver
they wrote many years ago (and add a mode that suits your



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