M17 RF Protocol: Summary

M17 is an RF protocol that is:

  • Completely open: open specification, open source code, open source hardware, open algorithms. Anyone must be able to build an M17 radio and interoperate with other M17 radios without having to pay anyone else for the right to do so.
  • Optimized for amateur radio use.
  • Simple to understand and implement.
  • Capable of doing the things hams expect their digital protocols to do:

    • Voice (eg: DMR, D-Star, etc)
    • Point to point data (eg: Packet, D-Star, etc)
    • Broadcast telemetry (eg: APRS, etc)
    • Extensible, so more capabilities can be added over time.

To do this, the M17 protocol is broken down into three protocol layers, like a network:

  1. Physical Layer: How to encode 1s and 0s into RF. Specifies RF modulation, symbol rates, bits per symbol, etc.
  2. Data Link Layer: How to packetize those 1s and 0s into usable data. Packet vs Stream modes, headers, addressing, etc.
  3. Application Layer: Accomplishing activities. Voice and data streams, control packets, beacons, etc.

This document attempts to document these layers.

.. [TETRA] Dunlop, John; Girma, Demessie; Irvine, James "Digital Mobile Communications and the TETRA System" Wiley 1999, ISBN: 9780471987925

.. [DMR] ETSI TS 102 361-1 V2.2.1 (2013-02): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Mobile Radio (DMR) Systems; Part 1: DMR Air Interface (AI) protocol" https://www.etsi.org/deliver/etsi_ts/102300_102399/10236101/02.02.01_60/ts_10236101v020201p.pdf