NPR New Packet Radio

NPR (New Packet Radio) is a custom radio protocol, designed to transport bidirectional IP trafic over 430MHz radio links (ham radio frequencies 420-450MHz). This protocol is optimized for "point to multipoint" topology, with the help of managed-TDMA. Bitrate is 50 to 500kbps (net, effective bitrate), depending on the RF bandwidth chosen. The radio modem is cheap (~80$) and home-made, with a 433MHz ISM module inside (flexible enough to be tuned over the whole 420-450MHz band). The modem is connected locally with Ethernet, therefore no specific software is needed on PC. The modem is easy to build and reproduce. You can add a DMR radio amplifier in order to achieve 20W radio power or more. The main usage is an extension of HSMM - Hamnet - AREDN networks. All the project is open-source : hardware, software, protocol specification.