Thursday, January 7, 2016

Networks and history

As you know, the MMDVM will support three data protocols, D-Star, DMR and System Fusion. Each is quite different in many ways, but what they do share is the in-built support for networked repeaters. Unlike FM where EchoLink and IRLP were late to the game, relatively speaking, and standalone FM repeaters were and are well established, the digital modes have known little else. This integration is much less clunky than anything on FM, with things like callsign routine (D-Star), reflectors (D-Star and DMR), talkgroups (DMR), and other good stuff.

This has only been possible, for the most part, by the use of open protocols. When I say open, I mean that the details of the protocol have been published and the developers have been available for discussion and in some cases changed things in the face of experience. This is not to say that the infrastructure of the system needs to be open source, the model of a closed open system (or is that open closed system?) works well and I’m not going to get onto my soap box and demand that ircDDB release all of its source code or else. As long as the protocol is open and published, I’m fine with that.

Now to a bit of ancient history. Back in 2009 when I started with D-Star, there was only one network, G2. This was the official Icom system, it offered callsign routing, add-ons added D-Plus and D-PRS. The custodians of G2 were, by the time I got up to speed on these things, somewhat reticent about allowing homebrew systems onto their network. This was mostly caused by the actions of one developer who wrote a very fine clone of G2 but through his testing which verged on the malicious, and toxic personality, managed to alienate all who dealt with him, myself included. The net effect was that the official G2 network was closed to homebrew systems and that was that. It was a reasonably large network, but things were about to change. A group of Germans started up the Open G2 network, using Icom software for the servers, just like the official G2 network but fixed to work properly, and the homebrew G2 clone mentioned above. The reflector system of choice was DExtra rather than D-Plus.

This network grew to be a significant fraction of the size of the official network, with my repeater software being heavily used. Yay!

In 2010 ircDDB was created, to do what G2 did, but much better. As one user said: ircDDB is a Ferrari compared to the G2 horse and cart, or something like that anyway. I was tasked with writing the official gateway software which after many years of development now supports D-Plus, DExtra, DCS, CCS7, D-PRS, D-RATS, localised voice announcements, DTMF control. AMBE regeneration, and other bits and pieces that I have forgotten about! The ircDDB network and the allied QuadNet system now account for many thousands of systems dwarfing the official G2 network which still continues.

I had the pleasure of meeting the official G2 guys and Robin AA4RE of D-Plus fame at Dayton in 2014, and found them to be excellent people. The damage had been done by our toxic developer above and it’s a shame that I wasn’t on the scene earlier, D-Star history may have been different.

 Also at Dayton I got interested in DMR properly and started planning some form of implementation. This would probably have become the MMDVM a year earlier than what actually happened but my private life took an interesting turn, Hi Liana! Radio went onto the back seat as I found domestic bliss

Back to networks. The DMR world feels like a re-run of the G2 debacle. In 2014 I met the DMR-MARC guys at Dayton, there was no other DMR network in existence at the time, and they made it very plain that nothing other than a pure bona-fide Motorola system would ever be allowed onto their network. They were rather aggressive on that point I thought, it didn’t help that the same people then went on to say that they ran my D-Star software and loved it! They didn’t see the irony of what they were saying, history was potentially repeating itself with them as the losers.

The first open closed DMR network was DMR+, the people behind this are the people behind DCS and CCS7 In the D-Star world. Shortly afterwards the BrandMeister network was started up. There is rivalry between the two, and I do not intend to choose one side over the other, I have cordial relations with both. They are both implementing my Homebrew DMR protocol to allow homebrew systems complete access to their networks at the same level as Motorola and Hytera systems. This is a big win for lovers of open systems and I commend both groups for their attitude.

Onto System Fusion. This is the most depressing as well as the one with the most possibilities. The official Wires-X network from Yaesu is very very closed, and I am sure any attempt to build some form of homebrew interface would be rebuffed, this is a shame as we amateurs have shown ourselves to be consistently capable of produce good robust systems more capable than the official offerings.

So let’s write that one off. I see no unofficial network emerging, which means that the System Fusion support in the MMDVM will be RF only initially. Fusion allows a number of audio modes, all mutually incompatible, but gets around this by decoding the audio to PCM before moving it around their network. This is clever in that it gets over the incompatibilities but also defeats one of the great strengths of digital voice system, using digital end-to-end for the best quality audio.

The field is open for an open closed, or even an open open network for System Fusion. I’m all ears, who’s going to be first?

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