M17 open-source, DMR-like

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M17 open-source, DMR-like

Post by SP2ONG » Fri Dec 20, 2019 3:44 pm

Maybe someone will be interested in information about an interesting project:

KB6NU wrote:On reddit, Wojciech, SP5WWP, just posted an item about his latest project, and open-hardware and open-software, DMR-like system called M17. He says that his goal is “create a fully functional, truly open-source and open-hardware system for digital radio communication. Something like DMR, but with open hardware too.” I have cobbled together the following from the FAQ and and a post on his website.

M17 is a community-driven, truly open, free to use digital radio system. It’s a a DMR alternative, if you will. All schematics and source code is available for free on github.

Wojciech says that he’s developing M17 because there’s no open platform for developing digital radio and because DMR isn’t really amateur-friendly. You can’t really experiment with it. He says, “It’s no fun using something, that’s only available at commercial retail. Is that true ham spirit?” He goes on to say that M17 provides all that’s missing in DMR, and because it uses the Codec2 vocoder developed by David Rowe, the voice quality is better as well.

Internally, M17 radios use an STM32F7 family microcontroller along with a SiLabs Si4463 RF front-end chip. The microcontroller samples the voice signal from the microphone using an ADC, encodes it with Codec2, and sends the encoded voice as a data packet. In addition, the radio has an RF power amplifier, an accelerometer (ADXL345) and a place for a GNSS module.

The coded speech bitrate is 3200 bits per second, and it is possible to send data packets alone or as embedded data along with voice channel. M17 does not currently support encryption, but the developers are working on AES implementation.

Wojciech has been working on the project for about a year now, and while he has made substantial progress, is looking for some help. Specifically, he’s looking for people with the following skills:

C programming (Raspberry Pi, STM32, PC)
PCB routing (preferably KiCAD)
Familiarity with 3D printing, CAD/CAM
Soldering, prototyping
Open mind – concept testing

If you have any interest in working with him on this project, you can contact him via email (w.kaczmarski@teletra.pl)
Source this message: https://www.kb6nu.com/m17-an-open-sourc ... ke-system/
https://www.reddit.com/r/amateurradio/c ... urce=ifttt

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Re: M17 open-source, DMR-like

Post by SP2ONG » Sat Dec 21, 2019 4:04 pm

It would be interesting if you could have firmware in the alternative OpenGD77 version with CODEC2 support according to the M17 specification

https://github.com/sp5wwp/M17_spec/blob ... otocol.pdf

Then we would have radios available to use the M17 repeater

I know the author Wojtek corresponds to G4KLX so that he can add M17 support to MMDVM

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Re: M17 open-source, DMR-like

Post by G4EML » Sat Dec 21, 2019 5:23 pm

It is unlikely that the GD77 hardware could be made to work with this.
From the limited information available it would appear that the proposed data link layer is completely different to DMR.

Because the GD77 uses a dedicated baseband chip (HRC6000) to encode and decode the DMR data it can not be used for other modes. There does not appear to be any way of bypassing the chip to directly access the modulator (or if there is we have not found it). This would be needed to be able to generate the data with firmware.

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Re: M17 open-source, DMR-like

Post by VK3KYY » Sat Dec 21, 2019 8:55 pm

I appreciate the work that the author has put into the project.

Kai and I did consider including the Codec2 codec in the OpenGD77, but it would then be incompatible with other DMR radios and there would not be enough space in the ROM to include both the Codec2 and AMBE codec.

The DMR standard is not proprietary, and does not specify a codec as part of the standard, so Codec2 can be used with DMR.
So don’t know why someone would decided to invert yet another radio standard.

If someone wants to recompile the firmware to use an alternative codec e.f. Codec2 they can do, but I think it’s use would be limited to Brandmeister talk groups not connected to repeaters, as you would probably be banned by system admins if you tried to use it on DMR MARC, as all everyone else would get from their radios is garbled audio.

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