refclock 28 gone wacky on me

Mike bellyacres at
Fri Jun 10 18:25:05 UTC 2016

On 06/09/2016 11:38 PM, Gary E. Miller wrote:
> Yo Mike!
> On Thu, 9 Jun 2016 22:25:54 -0400
> Mike <bellyacres at> wrote:
>> What I fail to understand is why this just seems to have
>> appeared out of thin air.  It's not like I just hooked this up
>> yesterday.  I have toyed with this thing for probably three years off
>> and on, never had anything like the offset I'm seeing.  Of course
>> there is no saved data from times when it was running well.
> My guess is it depends on the initial conditions.  Jiggle the system
> clock 1/2 second forward and back, restart gpsd a few times and
> you may see it come and go.
> You said you had used the HOWTO, I assume you updated gpsd from git.
> Maybe it is recently broken in git.
> Let me ponder this a while, and see if I can come up with a patch.  I'll
> need to study the code taking into account this new, and unexpected,
> data.
I'll experiment with that later and see what I can see.  Yes, gpsd is a 
very recent git pull,  Sat. (4/6/16) if memory serves.

Right now I finally got it hooked to a Windows machine, used the POS 
software that is reportedly for this specific module.  I found a setting 
that sets the NMEA messages to be sent at the top of the second.  This 
gets me back closer to what I seen in the past.

*    .PPS.            0 l   15   16  377    0.000 0.088   0.008
-    .GPS.            0 l   14   16  377    0.000 116.808   

I know they will both settle in better, experience tells me leave it be 
for at least a few hours.  Ultimately I can now log statistics and fine 
tune the fudge factor on NMEA to be much better.



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