APRS Igate Setup using Mobilinkd and APRX

APRS-IS => RF coverage in my area was weak, so I wanted to fill it in with an Igage. I already had a mobilinkd, Kenwood TM-V71 and a raspberry pi - so why not put them to work?

Major Tasks

  • Get the mobilinkd paired with the bluetooth
  • Setup rfcomm
  • Download and install APRX
  • Configure APRX

Bluetooth Setup and Pairing

This site: https://idefix.net/~koos/newsitem.cgi/1484944367 was very helpful. Since since pages come and go, I'll try to boil it down to the important stuff.

Install packages for bluetooth
sudo apt-get install bluetooth

Find your mobilinkd. You are looking for a MAC address, something like
this:30:14:11:xx:xx:xx Mobilinkd TNC2
hcitool scan

Prepare to pair. The PIN is 1234.
scan on
pairable on
agent on
pair 30:14:11:xx:xx:xx

At this point, the light on your mobilinkd should be flashing slower b/c it is paired

Setup a serial connection from the bluetooth device to /dev/rfcomm0 rfcomm connect /dev/rfcomm0 30:14:11:xx:xx:xx 1 &

APRX install

I built APRX from source because my first attempt was with a buggy older version on ubuntu. I pulled it from here: https://github.com/PhirePhly/aprx
If you don't have git, you'll have to install it.
sudo apt install git
Once you have it, you need to clone(copy) the source.
git clone https://github.com/PhirePhly/aprx.git aprx
Now that you have it, time to build it and install it
cd aprx
sudo make install

Did it build and install ok? This will show you the version and the help
aprx -h

Configure APRX

There should be a sample config file at /etc/aprx.conf. In installed vim, because I'm used to it. You can edit it how you'd like.
apt install vim
vim /etc/aprx.txt

At this point, the comments in the file and in the documentation are helpful, but I'll sum it up.

  • Set your callsign on the mycall line
  • Set your location using myloc
  • Set your APRS passcode
  • Select the best aprs2 server, look for #server and uncomment the best one for you. Being in the US of A, I picked noam.aprs2.net
  • Set a filter, because it is the nice thing to do. I went with filter "m/80"
  • Setup the interface to your mobilinkd (this section is there, just modify it)
    serial-device /dev/rfcomm0 19200 8n1 KISS
    callsign $mycall
    tx-ok false # do yo want to transmit?
    telem-to-is false # do you want to report number of packets sent, etc?
  • Setup the beacon
    cycle-size 30m
    Read the comments on beacon symbol and pick the appropriate one.
  • Setup the digipeater section
    transmitter $mycall
    Within the digipeater section, find the APRSIS source section
    source ARPSIS
    relay-type third-part
    viscous-delay 5
    ratelimit 30 # packets per minute
    filter -r/46.5/111.5/-150 # packets must be within a distance of this location

Start it up

Options -v and -d are really helpful when troubleshooting why something is or isn't gated. I found when going from ARPS-IS to RF, it wouldn't work right away because my station had been heard too recently. Leaving the software running longer to get some history makes it work more like you'd expect, so be patient.
aprx -f /etc/aprx.conf

Be sure to watch aprs.fi to see what is going on.