[ntp:questions] Re: problems with pps and meinberg gps 167

Martin Burnicki martin.burnicki at gmx.de
Mon Nov 24 10:20:18 UTC 2003


Nec wrote:

> Hi,
> i use a Meinberg GSP 167 with PPS but the PPS-Signal is not reachable
> although the status-bit PPSTIME is set.
> I built a ttl-to-rs232 gage converter (the function of it is correct ->
> inverst a +5V to -8.5V and -5V to +8.5V for rs232) and start the
> synchronisation and all the time this output is in ntp.log:
> 21 Nov 18:38:07 ntpd[493]: time reset +0.196016 s

The PPS signal provided by the GPS167 has a length of 0.2 s which is close
to 0.196 s in the log file, so it seems that your PPS input just handles 
the wrong slope of the PPS signal. 

You can invert the signal level by soldering, to feed the other GPS167's PPS
output with inverted level to your level converter. Alternatively,  you can
change the slope to be evaluated by the PPS input from "assert" (default)
to "clear" in ntp.conf by adding:

#pps device
fudge flag2 1

Additionally, you change the line

server mode 7 prefer


server mode 135 prefer

where 135 = 7 + 128.

128 stands for a flag bit which is OR'ed to the normal mode value to let the
parse driver enable PPS support for that device.

Hope this helps. By the way, you can also send support request email to
Meinberg if you need help with our devices.

Best regards,



Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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