Re: [chrony-users] PPS and NMEA same source not combined

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

The local NMEA source is probably ruled out because its time is outvoted by
the internet sources.  The internet sources will probably have an accuracy
around a millisecond. with a few milliseconds uncertainty. The NMEA will be
closer to 100ms out, and thus may well fall outside the error bands of the
internet sources and will thus be voted out.

How do you feed the NMEA to your system. What puts it into the SHM boffer?
gpsd?



William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
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On Sun, 19 Mar 2023, Mike Smith wrote:

> [CAUTION: Non-UBC Email] Rob, Yes I kind of understand your thinking and I was about to agree but
> surely if you have a more accurate local source, using that would be preferable?
> Mike.
>
>
>  
> [t_7edvEm.jpg?v=45]
> Kind regards, Michael A Smith.
>
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> My apologies for any incorrect information or typographical errors. Any opinions expressed are my own,
> and are not intended to offend. Anyone offended by anything stated, will likely have offended me, by
> being inconsiderate of my beliefs.
>  
>
>       On 19 Mar 2023, at 19:54, Rob Janssen <chrony-users@xxxxxxxxx> wrote:
>
>       That is how it should be!
>       When you have internet time sources, those are to be preferred over an NMEA source.
>       And the PPS source is to be preferred over both of these.  Add a "prefer" keyword to that
>       line.
>       NMEA should only come into play when you have no internet sources or they are over a very
>       jittery network.
>
>       Rob
>
>       On 3/19/23 20:37, Mike Smith wrote:
>             For some reason it’s now decided to take the NMEA time as primary.  Maybe I
>             should put the precision statement back into the NMEA line as that one has
>             much more latency as you described earlier.  I did previously have precision
>             1e-1 to get a second accuracy but found it kept preferring the internet time
>             sources then.
>
>
>
>
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