APRS Beacon

A command-line script for making pi-star hotspots visible on the aprs.fi map.

While MMDVMHost can be configured to forward APRS positional messages with no issue; when configured strictly for the DMR network the hotspot has no beacon capability.

Do I need this?

Only if you want your hotspot's location public on aprs.fi. In DMR or P25 mode, nothing else broadcasts it at regular intervals.

Pi-Star's Fusion, NXDN and D-Star gateways do beacon, so if you run one of those you don't need this. Don't enable one just for the beacon: on a simplex hotspot, extra modes compete with DMR.

Installation

Make sure your pistar hotspot has a callsign, latitude and longitude configured, and that APRSGateway has an APRS-IS server set. Keep in mind that this script does not reduce the accuracy of the coordinates. If you value your privacy omit a few decimal places, or set Latitude/Longitude in /etc/aprs_beacon.

To download and install:

cd /tmp
wget -O aprs-beacon.deb https://github.com/marek/aprs_beacon/releases/latest/download/aprs-beacon_all.deb

# make pistar filesystem writeable
rpi-rw

sudo dpkg -i --force-confold aprs-beacon.deb

# edit SSID suffix, APRS symbol and description
sudo nano /etc/aprs_beacon

# make pistar filesystem read-only again
rpi-ro

Installing the package replaces a manual install of version 0.1 (/home/mmdvm/aprs_beacon). --force-confold keeps an existing /etc/aprs_beacon.

To remove it: rpi-rw; sudo dpkg --purge aprs-beacon; rpi-ro.

Additional configuration

By default APRS Beacon is configured to update every 5 minutes. To change this edit the cronfile /etc/cron.d/aprs_beacon to your liking.

rpi-rw
sudo nano /etc/cron.d/aprs_beacon
rpi-ro

Description in /etc/aprs_beacon can use placeholders filled in from the hotspot's own settings, so one config fits every hotspot:

Placeholder	Becomes	From
{controller}	MMDVMHost or DStarRepeater	Pi-Star's Controller Software marker, /etc/dstar-radio.*
{mode}	Simplex or Duplex	Duplex= in /etc/mmdvmhost
{device}	e.g. RPi Zero 2 W	the board model in the device tree
{modem}	e.g. STM32-DVM / MMDVM_HS - Raspberry Pi Hat	the Radio/Modem Type, named as the Pi-Star dashboard lists it

The default {controller} {mode} Hotspot, {device}, {modem} gives MMDVMHost Simplex Hotspot, RPi Zero 2 W, STM32-DVM / MMDVM_HS - Raspberry Pi Hat. Comments are capped at 128 characters; the APRS spec's 43-character limit is for RF, and this beacon only goes to APRS-IS.

The beacon logs in to APRS-IS as CALLSIGN-Suffix, so it never collides with APRSGateway's own login. If the configured server can't be reached it falls back to rotate.aprs2.net.

Troubleshooting

Every run is logged to syslog:

grep aprs_beacon /var/log/syslog | tail

To see what would be sent without sending it, or to send one beacon now:

sudo -u mmdvm aprs_beacon --dry-run
sudo -u mmdvm aprs_beacon

login ... not verified means APRS-IS rejected the passcode; check the APRS-IS password in the Pi-Star configuration.

Building

./build.sh builds dist/aprs-beacon_<version>_all.deb from pkg/, using the version in VERSION. It needs dpkg-deb, so run it on Debian/Ubuntu or on the hotspot itself.

tools/smoke-test.sh dry-runs the beacon against fake Pi-Star config files and checks the exact packets: with no argument it tests pkg/ in the checkout (any bash 4.2+, macOS included via Homebrew bash), and tools/smoke-test.sh dist/aprs-beacon_<version>_all.deb tests the built package.

Pushing a v* tag that matches VERSION (e.g. v0.2.0) builds and smoke-tests the package in Debian bullseye (Pi-Star 4.2's release) and drafts a GitHub release with it; publish the draft to make it the latest download.