[ntp:questions] Help - Using a generic Trimble GPS with TSIP output?

R Jenkins not at pub.lished
Mon Apr 24 13:04:07 UTC 2006


Hi,

I'm trying to set up a local refclock using a Trimble 'Lassen SQ' GPS.
This is a navigation unit, not one of the Trimble timing devices.

The only refclock that appears to support this is the Parse one set for mode 
10. This is originally for a Trimble SV6 & as far as I can see the protocol 
should be the same as the Lassen SQ.

I've built NTP 4.2.0a with parse & tsip configured. It's on an Athlon 64 
machine running Centos 4.3-x86_64

Using ntpq -c peers all I get on the 'generic' line is a row of zeros. I 
have three other servers configured (one local & two internet) and NTP is 
otherwise working OK.

I've turned on debugging in the parse refclock.
Initially I was getting some invalid time code errors, with the data 0xff in 
place of some bytes but otherwise the data format looked OK. Setting the GPS 
for no parity cleared these errors.

I still get the occasional poll timeout error.

>From this, it appears that the GPS is sending tiem packets when polled (or 
it would not have been logging the parity errors), but for some reason the 
parse code is not able to decode them correctly??

Does anyone have any suggestions on how to get this working, or is there 
another refclock that will work with a basic TSIP GPS?
If it's relevent, I have compiled the kernel with PPS support: Kernel 
2.6.16.9 patched with ppskit-lite for 2.6.15 & the rejects edited in by 
hand.

So far I don't have any reference to PPS in ntp.conf, so I'm hoping this is 
not part of the problem.


ps. Is it possible to configure the standard source to build for /usr/sbin? 
I'm using /usr/bin for now but would like to get it in sbin as per the 
original redhat / centos files & can't find the appropriate config option.

Thanks for any help,

Robert.






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