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*        ###  APRS on Linux Using a Rigblaster Plug 'n Play  ###       *
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*                          July 13, 2020                               *
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A few weeks ago, I decided to set up an APRS beacon from my apartment. I
thought it would be a good challenge to use my older laptop that I've 
previously used for ham radio projects--mainly digital over HF.  Here's
a bit about that experience.

####################
The Hardware:

- Yaesu FT-7800R (2m/70cm mobile radio)
- An older Dell laptop (I'm too lazy to look at the model number)
- Rigblaster Plug 'n Play 


The Software:
- Ubuntu 16.04 32-bit
- Direwolf
- Xastir

####################

The good thing about the Rigblaster PnP is that support is built-in to 
modern Linux kernels (West Mountain Radio says that Linux kernel versions
3.8.4 and above have built-in support, but you can get drivers if need be
in case you have an older kernel version[1]).

I plugged it in and it shows up as /dev/ttyUSB0.  There are all sorts of 
rig configurations using hamlib, but my radio isn't specifically listed,
so I went the route of using Direwolf as a soundmodem.  That was...a bit
more challenging, but I came across a YouTube video from Retro Tech &
Electronics that was extremely helpful.[2]  I followed his directions
and set up /dev/PTT to be a symbolic link to /dev/ttyUSB0.  I don't think
it's an absolute necessity, but I figured I'd go through step by step. In
any event, it's not a major deal to create it.

I was having issues getting direwolf to execute.  I was running into an 
error about not having permission to write to one of the GPIO pins. As I 
was going through the direwolf.conf file, I noticed a configuration for
the GPIO pins, so I just commented those out since I was executing from
a laptop.  That seemed to work as Direwolf was writing decoded packets
that I was receiving on 144.390 MHz to the terminal.  Cool.

Time to transmit.  I launched and configured Xastir as shown in the
YouTube video.  Xastir uses Direwolf as a KISS TNC interface.  All
I really need to do is have the computer be able to key up my radio and
make sure that the audio is at appropriate levels to transmit and receive
packets through the sound card.  After I set and saved my configuration,
I hit "Transmit Now!".  It worked!

I checked APRS.fi--lo and behold, my location ended up on the map pretty 
much where I was (approximately since I manually keyed in my latitude and 
longitude).

Then I left it running for a while just to see what I could pick up. Quite
a number of folks running APRS northeast of Atlanta.  Plus, I live fairly
close to I-85 and the Gwinnett County airport.  A good bit of activity 
from truckers and some pilots who transmit their locations as they pass by.

Then I noticed something--apparently I missed a PBEACON configuration in 
the direwolf.conf.  The default had me located in Santa Clara whenever
the timer on Direwolf triggered a transmit.  Oops.

I was able to fix that pretty easily, and now it appears that everything
is functioning quite well.  You can check out my APRS station on 
APRS.fi[3].  It updates fairly regularly, but right now it's a comment
that has "finger drelcott@sdf.org" which has my SDF contact information 
so folks can drop me a line by email.

At some point, I may get a small weather station to send weather data to
make my station a bit more interesting (and useful).

I still think it's pretty neat.  I definitely recommend setting up an
APRS beacon even if it's just from your house.


[1] http://www.westmountainradio.com/kb_view_topic.php?id=OT21
[2] https://www.youtube.com/watch?v=9Ya0C308TQA&t=15s
[3] https://aprs.fi/info/a/W4GOP