Yo Hans! On Sun, 18 Jan 2026 20:45:51 +0100 Hans Mayer <[email protected]> wrote:
> fudge 127.127.28.0 refid NMEA
Fudgning NMEA is a bad idea. You want it to be an outlier, not in a
cluster with valid chimers.
> About 4 days ago I add a ntrip source to the gpsd configuration. It's
> running with
What kind of ntrip source? ntrip is like http, it is just a transport
layer. It might contain RTCM2, RTCM3, SPARTNv2, Trimble, or any other
of a large number of correction types.
Even RTCM3 does not say much. Which constellations? Which MSMx level?
Any proprietary u-blox messages? etc. Calulated or from a single
nearby station?
> Today I see that the offset for SHM(0) / 127.127.28.0 became
> extremely poor.
Yeah, the power to do good, is also the power to do bad.
> In the graph below you can see for SHM(0) the offset from 0h till
> about 1 PM without ntrip source
I see that, when my heater comes on. "offset" from what? Offset from
the terrible clock in you PC. That clock is very sensitive to many
things. The "offset" just means that your PC clock has drifted and the
PPS is trying to pull it back.
Before you continue, you need to setup, and use ntpvis.
> It seems that the offset jumps back and forth between 2 ranges.
Many sources of granularity, not enough info to say yet.
> The jitter values jump extremely up after 1 PM when I restarted gpsd
> with ntrip source.
Yeah, jitter goes up when you restart. You want the best stability,
don't touch anything!
> A the beginning of the day
> At the end of the day
Classic thermal. Get ntpviz running, and then add temp proves to it.
> And I am wondering, a ntrip stream should only send satellite
> correction data.
Huh? Should http only send cat videos? No.
> Is there a way to avoid this and make the SHM interface stable
> inclusive ntrip ?
Did you consider that unstable may actually be better?
"jitter" and "offset" are two aspeects of the same thing. Higher
"jitter" means lower "offset", and vice versa.
> If you need ( and probably you will need ) any additional information
> then I am happy to supply it.
What I need is for you to:
1. install and run ntpviz
2. install and read temp sensors
3. get an accurate local clock, like an Rb or Ceasium.
Measureing the "stability" of your PPS using your crappy PC clock is
like measuring distance in smoots.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
[email protected] Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin
pgpf4r447BW2s.pgp
Description: OpenPGP digital signature
