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==Overview==
==Overview==
M17 utilizes 4800 symbols per second 4FSK with a root Nyquist filter applied to the bitstream. Radio channels are 9 kHz wide, with channel spacing of 12.5 kHz. The protocol's specification is released under [[GNU_General_Public_License#Version_2|GNU General Public License]].
M17 utilizes 4800 symbols per second 4FSK with a root Nyquist filter applied to the bitstream. Radio channels are 9 kHz wide, with channel spacing of 12.5 kHz. The protocol's specification is released under [[GNU_General_Public_License#Version_2|GNU General Public License]]. The gross data rate is 9600 bits per second, with the actual data transfer at 3200.
Protocol allows for low-speed data transfer (along with voice), e.g. GNSS position data.
The mode has been successfully transmitted through [[EchoStar XXI]] geostationary satellite.<ref>[https://www.youtube.com/watch?v=xFeWDjmeZtE Testing M17 on Echostar XXI at 10° East]</ref>
M17 has received the 2021 [[Amateur Radio Relay League|ARRL]] Technical Innovation Award.<ref>[http://www.arrl.org/news/arrl-board-of-directors-bestows-awards ARRL Board of Directors Bestows Awards]</ref>
M17 has received the 2021 [[Amateur Radio Relay League|ARRL]] Technical Innovation Award.<ref>[http://www.arrl.org/news/arrl-board-of-directors-bestows-awards ARRL Board of Directors Bestows Awards]</ref>


==Voice encoding==
==Voice encoding==
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. The protocol supports both 3200 (full-rate) and 1600 (half-rate) modes.
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. The protocol supports both 3200 (full-rate) and 1600 bits per second (half-rate) modes.


==Error control==
==Error control==
Two methods are used for error control: [https://en.wikipedia.org/wiki/Convolutional_code convolutional coding] and [https://en.wikipedia.org/wiki/Burst_error-correcting_code#Interleaved_codes bit interleaving].
Three methods are used for error control: [[binary Golay code]], [[Convolutional code|convolutional coding]] and [[Burst error-correcting code#Interleaved codes|bit interleaving]].


==Bridging with other modes==
==Media==
Links to [[Digital mobile radio|DMR]] and System Fusion exist.<ref>[https://github.com/nostar/MMDVM_CM Douglas McLain's GitHub page]</ref>
Baseband audio sample etc.

==M17 over IP==
Access nodes and repeaters can be linked using ''reflectors''. Over 100 M17 reflectors exist worldwide (Jan 2022).<ref>[https://reflectors.m17.link/ref-list M17 reflectors list]</ref>


== See also ==
== See also ==
* [[Speech coding]]
* [[Speech coding]]
* [[Binary Golay code]]
* [[Convolutional code]]
* [[Burst error-correcting code#Interleaved_codes|Burst error-correcting code]]
* [[Permutation polynomial#Quadratic_permutation_polynomials_(QPP)_over_finite_rings|Quadratic permutation polynomials (QPP)]]
* [[Permutation polynomial#Quadratic_permutation_polynomials_(QPP)_over_finite_rings|Quadratic permutation polynomials (QPP)]]


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* [https://m17project.org/ M17 Project's website]
* [https://m17project.org/ M17 Project's website]
* [https://github.com/M17-Project M17 Project on GitHub]
* [https://github.com/M17-Project M17 Project on GitHub]
* [https://www.openwebrx.de Web based SDR by Jakob Ketterl, includes M17 decoder]


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Revision as of 17:13, 16 January 2022

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RF spectrum of M17 modulation

M17 is a digital radio modulation mode developed by Wojciech Kaczmarski SP5WWP et al. M17 is primarily designed for voice communications on VHF amateur radio band and above.

Overview

M17 utilizes 4800 symbols per second 4FSK with a root Nyquist filter applied to the bitstream. Radio channels are 9 kHz wide, with channel spacing of 12.5 kHz. The protocol's specification is released under GNU General Public License. The gross data rate is 9600 bits per second, with the actual data transfer at 3200. Protocol allows for low-speed data transfer (along with voice), e.g. GNSS position data. The mode has been successfully transmitted through EchoStar XXI geostationary satellite.[1] M17 has received the 2021 ARRL Technical Innovation Award.[2]

Voice encoding

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. The protocol supports both 3200 (full-rate) and 1600 bits per second (half-rate) modes.

Error control

Three methods are used for error control: binary Golay code, convolutional coding and bit interleaving.

Bridging with other modes

Links to DMR and System Fusion exist.[3]

M17 over IP

Access nodes and repeaters can be linked using reflectors. Over 100 M17 reflectors exist worldwide (Jan 2022).[4]

See also

References

  1. ^ Testing M17 on Echostar XXI at 10° East
  2. ^ ARRL Board of Directors Bestows Awards
  3. ^ Douglas McLain's GitHub page
  4. ^ M17 reflectors list
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