HamBSD FAQ: Automatic Packet Reporting System (APRS) [FAQ Index]

To be supported by nmea(4), your device must either attach to a serial port, or use a virtual (e.g. USB) serial port and use the NMEA 0183 protocol.

Assuming that your GPS device is attached to cuaU0 and will 4800 baud, edit /etc/ttys to add:

cuaU0   "/sbin/ldattach nmea"   unknown on softcar

(If your device uses another baud rate, or other exotic settings, see the ldattach(8) manual page.)

Then send SIGHUP to init(8) to cause the file to be reloaded:

# kill -s HUP 1

You can check the sensor is working correctly by using sysctl(8):

# sysctl hw.sensors.nmea0
hw.sensors.nmea0.indicator0=On (Signal), OK
hw.sensors.nmea0.timedelta0=-0.001002 secs (GPS autonomous), OK, Sun Oct 28 17:08:04.998
hw.sensors.nmea0.angle0=57.3748 degrees (Latitude), OK
hw.sensors.nmea0.angle1=-2.3849 degrees (Longitude), OK

APRS position reports can be sent using aprsd(8) and are configured with a file described by aprsd.conf(5).

In the simplest case, to beacon your current GPS position, create the configuration file at /etc/aprsd.conf with the contents:

beacon position sensor nmea0

Then enable and start the aprsd(8) service:

# rcctl enable aprsd
# rcctl start aprsd

Create a new file /etc/hostname.axtap0 with the contents:

!aprsisd -i axtap0 MYCALL

(Replace MYCALL with your callsign.)

Start the interface with:

# sh /etc/netstart axtap0

For more advanced options, see the aprsisd(8) manual page.