After analyzing D-Star, DMR and C4FM, we have seen how digital voice has followed different paths, each with its own characteristics.<\/p>\n
We have encountered systems created specifically for the amateur radio world, systems originating from the professional sector, and systems built around a complete commercial ecosystem.\u00a0All of them have proven to be valid solutions and have contributed significantly to the spread of digital voice communication in VHF and UHF.<\/p>\n
But they also share a common characteristic: none of them is completely open.<\/p>\n
The protocol, the codec, the hardware or the infrastructure may contain proprietary elements that prevent a complete understanding and free implementation of the system.\u00a0With Codec2 we have seen that this limitation is not inevitable.\u00a0An open voice codec is possible.\u00a0At this point, the next question becomes natural:<\/p>\n
is it possible to build an entire digital voice communication system designed from the beginning to be open?<\/p>\n
The answer to this question is called M17.<\/p>\n
M17 was created around 2019 thanks to the work of Wojciech Kaczmarski, SP5WWP, and an international community of developers and radio amateurs who shared a very specific goal: to create a modern digital communication system, completely open and designed for the amateur radio community.<\/p>\n
The difference compared with previous systems is fundamental.\u00a0M17 was not born as an adaptation of a professional technology.\u00a0It was not created as a commercial product.\u00a0It was not a proprietary system later partially documented.<\/p>\n
It was born directly from a different philosophy: everything must be studyable, implementable and modifiable.<\/p>\n
This choice influences every element of the project, from the transmission protocol to the voice codec, from packet structure to the possibility of creating alternative hardware and software implementations.<\/p>\n
From a technical point of view, M17 is a digital system for voice and data communications in VHF and UHF.<\/p>\n
Like the other systems analyzed previously, M17 starts from a fundamental principle: the analog voice coming from the microphone is converted into digital data, compressed, organized into packets and then transmitted through a radio link.<\/p>\n
The fundamental difference is that every step of the chain is documented:\u00a0the M17 protocol is public, the packet structure is public, the modulation method is public, and the voice codec used is open.<\/p>\n
This means that a researcher, a developer or a simple enthusiast can study the system without having to rely on confidential information or proprietary components.<\/p>\n
It is a philosophical difference before it is a technical one.<\/p>\n
One of the most important elements of M17 is precisely the use of Codec2 as the voice codec.\u00a0This creates a direct connection with what we discussed in the previous article.<\/p>\n
Codec2 demonstrates that it is possible to achieve efficient voice compression without necessarily relying on proprietary solutions.\u00a0M17 uses this possibility to build something broader: not just an open component, but an entire communication system in which digital voice is not a black box.<\/p>\n
The codec is therefore not merely a secondary technical detail.\u00a0It is the philosophical core of the project.<\/p>\n
If in traditional systems the codec often represented the point where the radio amateur had to accept a limit to their ability to understand the technology, in M17 that limit is removed.<\/p>\n
From the radio transmission point of view, M17 uses 4FSK modulation, that is, a four-level digital frequency shift keying modulation.\u00a0The choice is not accidental.\u00a0A 4FSK modulation provides good link robustness while maintaining complexity levels compatible with relatively simple software and hardware implementations.\u00a0The system operates with a 9 kHz channel bandwidth, making it suitable for use in the VHF and UHF bands normally used for digital voice traffic.<\/p>\n
Again, the difference compared with proprietary systems is not the technical choice itself.\u00a0Many design solutions can be valid.<\/p>\n
The difference is that in the case of M17 every choice is publicly documented.<\/p>\n
One of the most interesting aspects of M17 concerns operator identity management.<\/p>\n
While other systems use numeric identifiers or structures derived from the professional communication world, M17 directly integrates the concept of the callsign.\u00a0This choice has an important symbolic value.\u00a0The callsign is one of the fundamental elements of amateur radio culture: it identifies the operator, their authorization and their presence within the community.<\/p>\n
Including it directly in the protocol structure means designing the system starting from the reality of amateur radio, rather than adapting afterwards a technology created for different purposes.<\/p>\n
Another important element of M17 is the ability to transmit data as well.<\/p>\n
This aspect brings the system back toward one of the most interesting characteristics of modern amateur radio: the possibility of experimenting not only with voice communication, but also with protocols, applications and new operating modes.<\/p>\n
Digital voice is therefore not seen as a finished product, but as a platform on which to build new possibilities.<\/p>\n
It is a philosophy very close to the one that has characterized the world of HF digital modes for decades, where experimentation with protocols and transmission methods has often been an integral part of amateur radio activity.<\/p>\n
The main strength of M17 is, naturally, openness.<\/p>\n
For the first time we have a digital voice system in which every fundamental component can be studied and freely implemented.\u00a0This opens enormous possibilities for developers, independent manufacturers and experimenters.\u00a0Another advantage is the philosophical coherence of the project: protocol, codec and implementations all follow the same principle of transparency.<\/p>\n
However, there are also limitations.<\/p>\n
The first is inevitably adoption.\u00a0A new system requires time to build a community, develop compatible hardware and create operational infrastructures.\u00a0DMR, D-Star and C4FM can currently rely on thousands of devices and repeaters installed worldwide.\u00a0M17 still has to build this critical mass, although, from what I read online, it is growing rapidly.<\/p>\n
This is not necessarily a technological limitation, but it is certainly an important challenge.<\/p>\n
The true importance of M17 probably does not lie only in being a new digital system.\u00a0Its importance is above all cultural.<\/p>\n
M17 demonstrates that the amateur radio community can still design its own technologies, rather than simply adopting solutions developed in other contexts.<\/p>\n
Obviously, this does not mean that existing systems should be abandoned.\u00a0DMR, D-Star and C4FM will probably continue to play an important role for many years to come.\u00a0The issue is not replacing one technology with another.<\/p>\n
The issue is keeping possibilities alive.\u00a0The possibility for a radio amateur to look at a digital communication system and be able to say:\u00a0“I can study it. I can understand how it works. I can modify it. I can build something on top of it.”\u00a0And perhaps this is the most important point in the entire story of digital voice.<\/p>\n
Technology changes, modulations change, protocols change.\u00a0But one thing remains constant: the value of experimentation<\/strong>.<\/p>\n M17 is therefore not just a digital voice communication system.\u00a0It is an attempt to bring one of the fundamental principles of amateur radio back into the digital age:\u00a0the best technology is not necessarily the most closed and complex one.<\/p>\n It is the one that allows those who use it to experiment and continue learning.<\/strong><\/p>\n The title image shows one of the completely open projects available on wiki.m17foundation.org<\/a><\/p>\n![](\"https:\/\/www.i8zse.it\/en\/wp-content\/plugins\/textbox\/irev.png\")
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