M17 (amateur radio)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/M17_spectrum.png/220px-M17_spectrum.png)
M17 is a digital radio modulation mode developed by Wojciech Kaczmarski (amateur radio call sign SP5WWP) et al. [1][2][3][4][5][6] M17 is primarily designed for voice communications on the VHF amateur radio bands, and above. The project received a grant from the Amateur Radio Digital Communications in 2021[7] and 2022.[8] The protocol has been integrated into several hardware and software projects[citation needed]. In 2021, Kaczmarski received the ARRL Technical Innovation Award for developing an open-source digital radio communication protocol, leading to further advancements in amateur radio.[9]
Technical characteristics
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/96/M17_spectrogram.png/220px-M17_spectrogram.png)
M17 uses Frequency-Division Multiple Access (FDMA) technology in which different communication streams are separated by frequency and run concurrently. It utilizes 4,800 symbols per second, 4-level frequency-shift keying (4FSK) with a root Nyquist filter applied to the bitstream. Radio channels are 9
Voice encoding
[edit]M17 uses Codec 2, a low bitrate voice codec developed by David Rowe VK5DGR et al. Codec 2 was designed to be used for amateur radio and other high compression voice applications. It is based on linear predictive coding with mixed-harmonic sinusoidal excitation. The protocol supports both 3200 (full-rate) and 1600 bits per second (half-rate) modes.
Error control
[edit]Three methods are used for error control: binary Golay code, punctured convolutional code and bit interleaving. Additionally, exclusive OR operation is performed between data bits and a predefined decorrelating pseudorandom stream before transmission. This ensures that there are as many symbol transitions in the baseband as possible.
Application functions
[edit]The M17 protocol was primarily designed for amateur radio use.
- Callsign encoding: 48-bit field holding up to 9 alphanumeric characters eliminates the need of a centralized user-ID database.
- Encryption:
- Bit scrambler encryption: a pseudorandom binary sequence created by combining an exclusive-or bitwise operation on the audio or data stream and a linear-feedback shift register using one of 3 feedback polynomials with 255, 65,535 and 16,777,215-bit repeat periods.
- AES encryption: 128-bit block encryption cipher operating in CTR mode with user-selectable 128, 192 or 256-bit key.
- Slow-speed side channel for short and repeated data transfers, e.g. GNSS position data or telemetry.
- Text messaging.
Hardware support
[edit]In June 2024 Connect Systemsstarted shipping the CS7000, which is considered the first handheld transceiver with native M17 support. [12]
With a small hardware modification, TYT MD-380, MD-390 and MD-UV380 handheld transceivers can be flashed with a custom, free, open source firmware[13] to enable M17 support.
Bridging with other modes
[edit]Links between M17 and other digital voice modes and Internet linked networks exist, with several networks providing M17 access. Modes bridged include DMR, P25, System Fusion, D-STAR, NXDN, AllStarLink, EchoLink and IRLP.[14][15][16][17][18][19]
M17 over IP
[edit]Access nodes and repeaters[20] can be linked using reflectors. Over 180 M17 reflectors exist worldwide (January 2024).[21]
History
[edit]The project was started in 2019 by Wojciech Kaczmarski in Warsaw, Poland. A local amateur radio club he was a member of, was involved in digital voice communications. Kaczmarski, having experimented with TETRA and DMR, decided to create a completely non-proprietary protocol and named it after the club's street address - Mokotowska 17. As every part of the protocol was intended to be open source, Codec 2 released under the GNU GPL 2 license, has been chosen as the speech encoder.
Applications and projects with M17 support
[edit]- OpenRTX - free and open-source firmware for ham radios
- WPSD - digital voice software suite for amateur radio personal hotspots and repeaters
- DroidStar - digital voice client for Android
- SDR++ - multiplatform, open-source software defined radio receiver
- SDRangel - multiplatform, open-source software defined radio receiver/transmitter
- OpenWebRX - web-based software defined radio receiver
- mrefd - M17 reflector[22]
- rpitx - general radio frequency transmitter for Raspberry Pi[23]
- dsd-fme - digital speech decoder[24]
- mvoice - voice client and graphical repeater application (Raspberry and Linux)[25]
See also
[edit]References
[edit]- ^ Dan Romanchik's (KB6NU) blog entry on M17 Project (Nov 2019)
- ^ "Świat Radio" magazine, issue 11/2020, p. 50: "Transceiver TR-9", an article covering M17 (Polish)
- ^ Ham Radio 2.0 podcast, "M17 Project - New Ham Radio Digital Mode" episode (Sep 2021)
- ^ Linux in the Ham Shack podcast, episode 396: "M17 Deep Dive" (Mar 2021)
- ^ David Rowe's (VK5DGR) "M17 Open Source Radio" blog entry (Aug 2020)
- ^ "M17 Open Source Digital Radio System", Ham Radio Workbench podcast (Dec 2019)
- ^ Grant: M17 Open Protocol (Apr 2021)
- ^ Grant: M17 Project Popularization, Research and Development (Sep 2022)
- ^ ARRL Board of Directors Bestows Awards
- ^ Testing M17 on Echostar XXI at 10° East
- ^ AMSAT-DL Twitter entry on QO-100 wideband transponder M17 experiment (Apr 2021)
- ^ Zero Retries 0162
- ^ OpenRTX - free and open source firmware for ham radios
- ^ Douglas McLain's (AD8DP) GitHub page
- ^ Australian Multimode Network
- ^ Pride Radio Network
- ^ FreeSTAR Module-X
- ^ ANZEL Multimode VoIP/RoIP Network
- ^ USRP2M17 Bridge
- ^ RepeaterBook list of M17 repeaters
- ^ M17 reflectors list
- ^ Early, Tom (2023-09-09), MREFD, retrieved 2023-12-03
- ^ F5OEO (2023-12-02), About rpitx, retrieved 2023-12-03
{{citation}}
: CS1 maint: numeric names: authors list (link) - ^ lwvmobile (2023-12-02), Digital Speech Decoder - Florida Man Edition, retrieved 2023-12-03
- ^ n7tae. "M17 Digital Voice, now using FLTK".
{{cite web}}
: CS1 maint: numeric names: authors list (link)
Related links
[edit]- M17 Project's website
- M17 Project on GitHub
- Twitter feed
- WPSD project page
- Robert Riggs' (WX9O) M17 baseband encoder/decoder library (C++, GPL)
- OpenWebRX - web based SDR by Jakob Ketterl (DD5JFK), includes M17 decoder
- SDR++ - free, open source SDR software with M17 support
- mvoice - an open source program to connect to M17 reflectors