Re: Multiple TPV lines per sec?

[Gary E. Miller]

Yo Tor!

On Tue, 8 Jun 2021 19:47:51 +0200
Tor Rune Skoglund <trs@fourc.eu> wrote:

> > This is because of your receiver firmware changing its output due to
> > changing conditions.  Nothing can be done about it.  All GNSS
> > receivers do it.  
> 
> OK. I am just wondering why restarting gpsd, even in read only mode, 
> changes that output and what that condition then might be...?

gpsd did not change anything, your receiver changed something.

The receiver sends stuff to gpsd, and gpsd forwards it.  What your
receiver sends, and when, can vary like the weather.  Garbage in,
garbage out (GIGO).

The way to see this is to capture your receivers's raw output this way:
gpspipe -|R > raw.log

Then look at it and you can start to guess why gpsd forwaards what it
does, when it does.

> > Or, live with it.  It is perfectly normal and expected.  
> 
> Yes.... That might very well be the final outcome. We just need to
> make sure we report the right data back to the cloud system.

Other users don't care about the "final output", they care about the
latency of the initial output.  So gpsd output some TPV early, so the
time is not too lagged, then if more data dribbles in, that is reported
later.

What you can do is check for the next time stamp, then you know you have
all the data on the old timestamp.  Of course you may end up waiting a
long time, or entirely missing the last fix.


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

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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