DAPNET

Members of the ham radio activity group at RWTH Aachen University designed and developed DAPNET from scratch as a modern software approach.

[3] The recommended frequency for DAPNET is 439.9875 MHz,[4] which is part of the 70-centimeter band dedicated to amateur radio use.

For a low-power transmitter you can use Raspberry Pi with unipager[5] and MMDVM-modem[6] installed, and to make the coverage area several miles, a radio amplifier needs to be added to its output.

[7] The coverage area of the transmitter can be up to 20 km (12 miles), depending on the terrain and the height of the antenna.

They can be easily tuned to the desired reception frequency and also offer many other possibilities, such as receiving bulletins - messages sent to all recipients.