Re: ubxtool set GLONASS L1/L2

[Gary E. Miller]

Yo John!

On Wed, 6 May 2020 16:10:16 -0400
John Ackermann N8UR <address@hidden> wrote:

> Looking in the ubxtool source I found this, at line 6553:
> 
>        elif 6 == gnssId:
>             # GLONASS
>             if '2' == opts['parm1'] and enable:
>                 # The NEO-M9N ACKS, then ignores if 0x11 is sent
>                 m_data[10] = 0x11   # flags L1, L2
>             else:
>                 m_data[10] = 0x01   # flags L1
>         else:
>             # what else?
>             m_data[10] = 1      # flags L1

I'm still catching up on email, that was my next place to look.

> could it be that either this elif or the else in this test are
> catching more than just the M9N and forcing the flag to L1 instead of
> L1,L2?

That code is correct.  That code has nothing at all to do with the
model of the receiver.  Currently ubxtool has no way to know the model,
protocol version, or anything else about the receiver.  For some reason
people expect ubxtool to use quantum tunnling to know the receiver.

The code only knows what you tell it to do.

> (This is a SWAG, as I don't know the guts of the ubxtool code at all
> and was just searching "GLONASS" for interesting things.)

You got pretty close.

The problem is that if you try to enable L2 on a non-L2 capable receiver,
then the receciver ACKs it, then ignores it.  Not even a Lassie error.
That took me a long time to discover, and still give me nightmares.

The fix was to add the ",2" option so you the user, can tell ubxtool to
enable L2 in addition to L1.

So the command for you to send is:
    ubxtool -w 1 -P 27.10 -e GLONASS,2 ::/dev/ttyACM0

Note the ",2".  Yes, it is not documented.  I added that in the short
time I got to play with an M9T.  Send a doc patch if you think you know
a good way to say this.  I'll patch the ubxtool help to mention it.

I'm not sure why you are spcifying the device.  Are you also running RTK?

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

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

pgp8zE4jL1C3E.pgp
Description: OpenPGP digital signature