Re: Attempting to access the GD-8200 GPS

[Gary E. Miller]

Yo Stuart!

On Thu, 14 Jul 2022 20:27:12 -0400
Stuart Blake Tener <stuart.tener@bh90210.net> wrote:

> I am running Kali Linux on a General Dynamics (Itronix) GD-8200  
> laptop, which I recently became aware has a GPS board in it with a  
> Leadtek LR9548S (module) as one of the board's components.

I found the user manual here:

https://www.manualslib.com/manual/673864/Leadtek-Lr9548s.html

That says it is basedo on the  SiRFstarIII chip.  That is not a very
good receiver compared to current products.  It likely will only work
when outdoors with a good skyview.

It says it talks NMEA-0183 and SiRF Binary.  Defaulting to NMEA.

So it should work with gpsd just fine.

> I installed the suite of gpsd and its associative utilities
> thereupon, however I am trying to get my arms around fully
> configuring gpsd so I can leverage it to it's maximal extent.

Nothing you need to do, except start gpsd.  Maybe like this:

        gpsd -n /dev/ttySXX


> Towards
> the end of this epistle I shall instantiate the /etc/default/gpsd
> file that I am using. Any suggestions that might allow me to more
> greatly optimize it would be most greatly appreciated.

Ugh.  systemd(umb) and gpsd do not play well together.  Actaully,
nothing plays well with systemd(umber).  But your choice.

> As such,I do have some several questions for the group:
>   1) After attempting to use gpsmon,

gpsmon is a debug tool and is depreacted.  It only uses gpsd in pass-thru
mode, so does not tell you how gpsd is handling the device.  Don't use
it.  Use cgps, xgps, etc.

> 2) Is seems there is no way to get GPS sentences from the receiver  
> unless gpsd uses 4800 baud, is there a way to get gpsd to use a
> higher baud (and for the GPS receiver to abide by it too)?

gpsd will autobaud to what the reciver is sending you.  You need to
configure the receiver, not gpsd.  You can try to use "gpsctl -s SPEED"
to change the device speed.  But speeding it up will not fix that it
is just and old and slow device.

> 3) My GPS receiver seems to be having some problems, as I get GPS  
> sentences from it but no longitudinal or latitudinal data.

My guess is you have no fix and see few GPS satellites.  YOu need to
go outdoors.


> Is there a
> manner by which I can "reset" the GPS so it obtains the new almanac  
> and ephemeral data?

Nope, nor is there ever a need to.

> I know that a GPS needs to be reset sometimes if it has not been used
> in a while or was moved (whilst powered off) a great distance.

Not for decades.  Just let it have a good, outdoor, skyview for about
30 minutes and it will update itself.

> Maybe the GPS receiver board needs to be replaced?

Yeah, with something not 14 years old.

> I suspect it may  
> need to be, as it stands absent positional data nor is it noticing
> any more than a singular satellite. Can anyone suggest any meaningful
> diagnostic procedures I can exact to determine authoritatively what  
> might be underpinning instigate to the lack of functionality
> described herein above?

Look at cgps, and check that you see at least 4 satellites.

> 4) What, if any, inexpensive USB GPS receiver could I use that would  
> offer PPS functionality?

That depends on a lot of factors.  In almost all cases you will need
a serial port, and laptops don't have those anymore.

> 5) How can I determine if my current GPS can support and/or configure
> PPS functionality?

Pin 8 on the chip is PPS.  But what your carrier board does with it is
anyone's guess.  You could check that the PPS kernel driver is loaded
and look for /dev/pps0.


>     # Devices gpsd should collect to at boot time.
>    # They need to be read/writable, either by user gpsd or the group
> dialout. DEVICES="/dev/ttyS2"

Makes sense.

>    # Other options you want to pass to gpsd
>    GPSD_OPTIONS="-n --speed 4800"

If you force 4800, you'll not be able to change the speed later.
     
>    # Automatically hot add/remove USB GPS devices via gpsdctl
>    USBAUTO="true"

Why?

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

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