Also known as: M17 Project
The M17 Project is an open-source community that develops the royalty-free M17 amateur digital-voice protocol along with open hardware and software implementations.1
Overview
Founded around 2019, the M17 Project is a volunteer, community-driven effort — closer in spirit to an open-source software project than to a formal standards body like ETSI or the TIA. Its members are amateur-radio operators and engineers who set out to build a modern digital-voice and data protocol that is completely free of licensing constraints, in reaction to a land-mobile world where the vocoder is almost always the patented AMBE family from DVSI. By choosing the open, patent-free Codec 2 vocoder instead, M17 can be implemented, redistributed, and built into hardware by anyone without paying royalties — which is not possible for AMBE-based systems like DMR or P25.
The project develops far more than a paper specification. The M17 air interface is a 9600 bit/s 4-FSK waveform in a 9 kHz channel carrying Codec 2 voice with convolutional FEC, plus optional stream encryption and a reflector system for internet linking. The community also produces open reference firmware, the “Module17” and OpenRTX-based radio hardware, gateway software, and gateways to and from other digital modes. Everything — the protocol document, the source code, and the hardware designs — is published under open licences. Because M17 lives in the amateur bands, it operates within the allocations that national regulators (the FCC in the US, Ofcom in the UK) grant the amateur service under the international ITU plan, and amateur-service advocacy for those allocations comes from bodies such as the ARRL and the IARU.
Relevance to SDR
The M17 Project’s radical openness is exactly what makes it interesting from an SDR and decoding standpoint: because both the air interface and the vocoder are open, a fully free, end-to-end M17 receiver is possible with no patent shadow and no need for an external AMBE dongle. That is a genuine rarity in digital land-mobile radio, where the vocoder patent almost always forces a compromise. For anyone learning how digital voice works, M17 is also the most transparent case study available — you can read every stage from the 4-FSK symbols to the decoded Codec 2 audio in open source.
GopherTrunk includes M17 link-layer support, decoding the frame structure and stream metadata, and because the stack is open there is no licensing barrier to doing so. This makes M17 a clean example of the honest end of the spectrum: an open community protocol that a pure-Go decoder can handle completely, in contrast to proprietary systems where at least the vocoder is closed. See the digital protocol landscape lesson for how M17 compares with the commercial digital standards.
Sources
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M17 Project — the project’s official site, home of the royalty-free M17 protocol, open hardware, and reference software. ↩