[gpsd-users] gpsd as time source Ubuntu 12.04

[Steve Bourland]

First off, I hope this doesn't count as clutter for most of the readers, I 
am posting this primarily to document my efforts so I can find them in the 
future when I run into problems, but hope others find it useful.

I have been running a Garmin 18 LVC connect to an Ubuntu 10.04 system as 
my NTP time source for over two years with wonderful results.  I then 
began migrating to Ubuntu 12.04 without thinking too much about it.  I 
finally became aware of tremendous jitter (constantly bouncing from ~1 to 
over 30) from my NTP master and discovered that gpsd was not providing the 
PPS signal to ntpd.  Investigating the issues, I found indications that 
chronyd might be a better tool for my master server, so I installed it and 
set it up to use both shared memory and a socket for communications with 
gpsd.  (side note, online it was indicated that the socket might provide 
better resolution, but I would think shared memory was better, does anyone 
have any thoughts on this?).  I noticed that under Ubuntu 12.04, the 
default installation of chronyd has S83 links in the rcN.d directories, 
while gpsd has S26 links.  During debugging gpsd would complain about not 
having the socket available if started before chronyd, so I manually moved 
the chronyd links to S21 (this did not solve the lack of PPS on reboot, so 
I can't say it is necessary).  What finally did get the PPS working 
automatically on reboot was what I consider a very crude hack of adding 
the following to /etc/rc.local:

service gpsd stop
stty -F /dev/<Garmin serial port> 4800
service gpsd start

I came to this solution after reading about a similar problem in this 
post:
http://lists.nongnu.org/archive/html/gpsd-users/2012-04/msg00063.html

I hope this is helpful for anyone else be trying to use their GPS as a 
master time source under Ubuntu 12.04.