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Re: [gpsd-dev] Meaning of negative PPS offset?

From: Gary E. Miller
Subject: Re: [gpsd-dev] Meaning of negative PPS offset?
Date: Tue, 26 Aug 2014 20:18:49 -0700

Yo Eric!

On Tue, 26 Aug 2014 23:04:41 -0400
"Eric S. Raymond" <address@hidden> wrote:

> Gary E. Miller <address@hidden>:
> > >  Basically this ignores PPS until the clock is
> > > close, which sort of makes sense.
> > 
> > Which is what we used to do.  The 3.11 PPS patches, which I have not
> > tested or inspected, were intended to speed up time lock.  In theory
> > they should work.
> Nit exactly.  The only recent change to the PPS logic that wasn't from
> you was a change by Miroslav Lichvar intended to handle longer PPS
> intervals.  

Yes, and I see why that patch broke the PPS under certain conditions.
You may have improved it, but it is still problematic and will result
in negative (non-sensical) offsets.

> It had an error which I fixed.  After the fix,  I lived-tested it
> with the GR-601W and it seems to work.

Yes, the error is only under certain conditions.  I'm still lookong
at the code, but the wrong timestamp is used.  It shuold be the
time stamp when the NMEA was detected, not the time the NMEA stamp
says it was.  That creates a race.

> You mentioned in a previous mail that autobauding is failing for
> you. I dimly recall that you've had this problem before and it was a
> local config issue.  That code has been stable/working for a long
> time. 

I'm not ready to report on that.  Just that something odd is happening to
me.  Something that did not happen in the spring.  Something that is
only happening on some of my test setups.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588

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