M17: een open-source, DMR-achtig systeem

Bron: KB6NU

An M17 radio prototype.

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) or on LinkedIn. It all sounds pretty cool to me.

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