Re: NTPsec reports excessive jitter from GPSD/KPPS SHM

[Gary E. Miller]

Yo Nick!

> On Sun, 08 Mar 2020 01:49:00 +0000
> "Nick Burkitt" <address@hidden> wrote:
> 
> > Thanks - does the order matter? I've been using  
> 
> Not really.
> 
> > gpsd -n /dev/pps0 /dev/ttyACM4  
> 
> That should be fine.  But I admit I never do it in that order.
> 
> > and seeing those large PPS jitter numbers in NTPsec
> > NTPsec doesn't seem to be able to find SHM(1) at all  
> 
> More likely gpsd is not finding it.  ntpshmmon will tell you.

Oh, I forgot.  When you do it "/dev/ttyAMC4 /dev/pps0" then
the GPS is on SHM(0) and PPS is on SHM(2).

The way you did it, the PPS is on SHM(0) and the GPS on SHM(2).
Your 1.4 micro second jitter is pretty good.  We used to think
that 1 micro scond jitter was as good as you could get.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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