Most amateur radio operators who use digital radios typically use the DroidStar software, right? Whether on a mobile platform or a desktop platform, when using DroidStar, most people select DMR mode. In the latest version of DroidStar, there is an M17 mode in the dropdown list. I think most people are unfamiliar with this. Today, I'll introduce what the M17 mode is.
M17 projectLaunched for the first time in 2019, it was initially developed by Wojciech Kaczmarski (callsign SP5WWP) and others. Today, it is an open-source digital communication project specifically designed for amateur radio enthusiasts, developed by a team of radio hobbyists from around the world.
The M17 project encompasses two main aspects: open-source code (including protocols, software, and firmware) and hardware (devices).
M17 Protocol:
This protocol was designed from the outset with the core principles of being open source, fully documented, and free from patent restrictions. Its design philosophy emphasizes openness and technical freedom; it is completely open-source from the physical layer to the application layer, without the traditional limitations imposed by manufacturers of two-way radios. This means that the M17 protocol's source code is publicly available, allowing anyone to view, modify, and use it. It fully supports both voice and data transmission, aiming to replace proprietary digital radio protocols (such as DMR, Fusion, D-Star, etc.). Its primary design is for communication in VHF and above amateur radio frequency bands, providing a more open, flexible, and scalable communication solution.
The M17 protocol utilizes advanced 4FSK modulation at the physical layer, while also employing FDMA (Frequency Division Multiple Access) instead of TDMA (Time Division Multiple Access). This is achieved through carefully designed preamble codes and a unique bit type allocation scheme to ensure stable signal transmission. Furthermore, by combining an efficient error correction mechanism, the reliability of the link is enhanced. At the data link layer, it supports flow mode, packet mode, and BERT testing mode, meeting communication needs in different scenarios. The application layer is specifically optimized for amateur radio voice and data applications, using the open Codec 2 voice encoder.
Furthermore, as a cutting-edge digital protocol, it achieves effective integration between radio and the internet through Internet Protocol (IP). The standard IP framework, combined with the design of control data packets, not only expands communication channels for amateur radio but also provides possibilities for remote control and management.
ClickM17 Protocol Specification DocumentAvailable for viewing.
Hardware:
The TR-9 open-source handheld radio was the initial prototype device. As of February 2025, the main hardware devices currently available as open-source for the project are:
The following devices can be modified to support M17 (the following is a partial list; for the complete list, please refer to)WiKi(See also:)
The following devices can directly communicate using M17 when used with Module 17 or software (the following is a partial list; for the complete list, please refer to).WiKi(See also:)
- FT-817
- FT-991A
- FT-7800
- IC-706mkIIg
- IC-9100
- Teasycom MD-380/390
- ……
In 2021, SP5WWP received the ARRL (American Radio Relay League) Technology Innovation Award for developing this open digital radio communication protocol. This achievement has furthered the development of amateur radio. To better represent and protect the interests of the M17 protocol community, the M17 Foundation was formally established in December 2024, with the aim of providing a solid legal framework for the protocol.M17 Foundation websiteOfficially launched in January 2025.
The M17 protocol currently has over 50,000 users in the global amateur radio community. Its 4FSK modulation and Codec2 encoding/decoding technology support voice transmission rates up to 4,800 bps. The protocol uses the GPLv3 license, and its GitHub repository has received over 3,200 stars, forming an active open-source community ecosystem.
Okay, that's it for now. The next post will cover the hardware modifications and flashing of the BaoFeng DM-1701 to enable M17 communication. Stay tuned!
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