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

[Chris Dew]

    Hi Gary,
    
    Thanks for your reply.  Here's the information you requested:
    
>    what version gpsd,
>     
    root@C934E761:~# gpsd --version
      gpsd: 3.22 (revision 3.22)
      
    
>    gpsd binary from where,
>     
    root@C934E761:~# dpkg --list | grep gpsd |
      head -1
      ii  gpsd     
                                                                    
      3.22-4+devuan2                     arm64        Global Positioning
      System - daemon
      
      root@C934E761:~# cat /etc/apt/sources.list | head -1
      deb http://deb.devuan.org/merged/ chimaera main contrib
      non-free
      
    
>    what hardware are you running on
>     
    iMX8M
      
    
>    what command line to start gpsd,
>     
    root@C934E761:~# ps -ef | grep gpsd | head -1
      gpsd      3332     1  0 08:10 ?        00:00:07 /usr/sbin/gpsd -n
      -P /run/gpsd.pid /dev/ttymxc1
        
      
>    serial or USB connection,
>     
    serial
    
>    how are you measuring "arrival"
>     
    By eyeball.  Do you know of a time-stamping gpsd client?
    
> See if "gpspipe -w" or cgps works better.
>     
    No, I see the same batching in each of these.  (I have disabled all
    other gpsd consumers, with no noticeable effect on the batching.)
    
    
    Could you suggest a way that I could see whether the traffic from
    /dev/ttymxc1 into gpsd is also batched?  This might be a ublox
    issue, rather than gpsd.
     
    Thanks, Chris.

On 15/10/2024 21:07, Gary E. Miller wrote:

> Yo Chris!
>
> On Tue, 15 Oct 2024 09:35:36 +0100
> Chris Dew <chris.dew@thorcom.co.uk> wrote:
>
> > I've successfully used "gpsctl -c 0.1" to enable 10Hz updates on a 
> > u-blox MAX-M10S.
> > I get 10 fixes per second, but they all arrive together, once per 
> > second.  (I'm using telnet to rule-out application issues.)
> >       
> Got some more details?  Like:
>    what version gpsd,
>    gpsd binary from where,
>    what hardware are you running on
>    what command line to start gpsd,
>    serial or USB connection,
>    how are you measuring "arrival"
>
> What you describe is not normal.
>
> I would certainly not trust "telnet".  So many flavors that behave
> differently.
>
> > How can I get these TPV records to be individually delivered, 100ms
> > apart?
> >       
> See if "gpspipe -w" or cgps works better.  UNIX buffering can be
> anywhere and everywhere.  They weill never be evenly spaced, the M10S is
> not smart enough to do that.
>
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> 	gem@rellim.com  Tel:+1 541 382 8588
>
> 	    Veritas liberabit vos. -- Quid est veritas?
>     "If you can't measure it, you can't improve it." - Lord Kelvin
>
>

--

Chris Dew / Senior Developer
Email: chris.dew@thorcom.co.uk

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