Re: How to avoid 1Hz batching of 10Hz GPS fixes?

[Gary E. Miller]

Yo Chris!

On Fri, 18 Oct 2024 11:48:31 +0100
Chris Dew <chris.dew@thorcom.co.uk> wrote:

> > But, before you do any of that, update to gpsd 3.25 or better yet
> > git head.  
> Now using HEAD:

Good.

> >>>      serial or USB connection,  
> >> serial  
> > What speed?  
> 9600

That is WAY too slow for 10Hz.  The output of "ubxtool -t -p STATUS"
will likely show your output buffers are 100% full.  No pause bewteen
packets because there is not enough speed to get the all out, and have
a pause.


> > Or "ubxtool -t".  Try ubstool both with, and without gpsd running.  
> Using ubxtool -t when gpsd is running shows *8* and _9_ batched 
> UBX-NAV_PVT messages per second.

Yeah, classic buffer overflow.  The GPS is filling the serial link
and still needs to drop messages to keep up.

> Notice that the (bold/underlined) arrival times are batched, but that 
> the "nano" times are correctly 100ms apart.

Sorry, I dont udnerstand what you mean.  And you output corrupted
with asterisks...

> > without gpsd running.  
> Using ubxtool -t when gpsd is stopped:
> 
> root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool -t
> ubxtool: failed to connect to gpsd [Errno 111] Connection refused

Sotty, I figured you would know to add the "if /dev/ttyaxc1" parameter

> Can I make ubxtool connect directly to /dev/ttymxc1, without gpsd?

Yes, that is what I asked for.  You just need the "-f" parameter.

> I tried:
> 
> root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool 
> --device=/dev/ttymxc1
> ubxtool: failed to connect to gpsd [Errno 111] Connection refused

"-f XX" not "--device".  Spend some time with the man page and
the unxtool examples.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
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