Proposal - drop the GPSD JSON driver

Gary E. Miller gem at
Sun Oct 23 01:04:16 UTC 2016

Yo Hal!

On Sat, 22 Oct 2016 02:31:01 -0700
Hal Murray <hmurray at> wrote:

> >> I assume that using a pipe or socket rather than SHM would fix
> >> that.  
> > Probably, but then we run unto buffering jitter again.  
> Are we on the same wavelength yet?  Have we agreed that latency is
> not critical?  If so, why is jitter important?

Latency is critical, jitter is important, but the GPSD-JSON driver does
not add any.  As you said ealier, the deltas are computed in the kernel
(for KPPS) or in gpsd (for PPS).  The gpsd sends that to ntpd. ntpd does
not even look at that interval more often than the defaullt 64s poll
interval.  So a few extra fractions of a second encoding, transmitting,
and decoding, is swamped in the 64s poll interval.  Even with the now
possible 1 second poll it in insignificant.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at  Tel:+1 541 382 8588
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