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Enabling APRS support

A project log for Raspberry Pi SDR Cyberdeck

A portable, rugged, self-contained system to suit all your RF SIGINT needs in every environment.

Tom MladenovTom Mladenov 11/03/2020 at 23:480 Comments

Support was added to monitor and view APRS (Automatic Packet Reporting System). The concept is that generic data provisioning services (APRS, etc) can be launched with one button without need to run commands or start servers/processes.

A networked AGWPE engine was added to Xastir with localhost:8000 address.

To get APRS data, rtl_fm is used to tune to 144.8 MHz (in Europe) and pipe the samples into direwolf which acts as a server and accepts clients connections on port 8000. Upon launching the service from the GUI, the following command is run:

rtl_fm -M fm -d $INDEX -f 144.800M -s 24000 - | direwolf -t 0 -r 24000 -D 1 -B 1200 - & > /dev/null && echo $! > /home/pi/tmp/aprs.pid

 The .pid file is later used to stop the monitoring using:

pkill -F /home/pi/tmp/aprs.pid

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