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A challenge - document M17 data use
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Apologies for being missing on this list. I’ve been keeping an eye on it, and eagerly read any postings. The subscriber count has grown to 158, with 40 distinct topics discussed, since its creation on 2024-05-31. Those pieces included MMDVM supporting M17 as “just another digital voice mode” enabling repeaters (that have incorporated an MMDVM) to provide M17 service, M17 “modems”, the Mobilinkd TNC3 and TNC4, modifications for radios developed by OpenRTX, and most recently, the Connect Systems CS7000 M17 and CS7000 M17 PLUS portable radios. Other M17 “pieces” are referenced in the (new to me) M17 (amateur radio)?Wikipedia article - . (Kudos if the author of that is on this list.) I had a secondary, but strong reason for reason to?promote, encourage, evangelize M17 in Zero Retries. M17 was the first digital voice mode in use for Amateur Radio that (as best I understand it) incorporated data as co-equal to digital voice. As in, you can transmit data as easily as digital voice, and data transmissions would be handled through all M17 infrastructure, especially repeaters. It’s still queued up for me to document the “dirty details” of how poorly data is accommodated in DMR, D-Star, System Fusion, and P25… “data capability” is present in all of those, but it’s so poorly implemented as to be impractical for actual use in Amateur Radio. Here’s MY problem with data in M17… I have no idea HOW to actually use the data capability of M17. I haven’t (to date) seen a “Using Data on M17 for Dummies” guide. I should, and have had on my to do list for a while, buy a TNC4 and learn how the TNC4 handles data over M17. Candidly, I have my (writing and research) “hands” full at the moment with various high priority projects in Zero Retries to dive into this and learn the details and document them myself. Not to mention a bit of support to M17 behind the scenes. So… the challenge you “M17 USERS"… could one of you experts in using M17 (and there are a number of you on this list) dig out the details and write up exactly, in detail, how one uses data on M17? PLEASE don’t be intimidated by the need to “write a formal paper” or an article or any of such extraneous issue. What’s needed is the detailed information about how to use data on M17. If someone is able to explain / document it, I can clean it up and publish it with full credit to the author(s). This writeup isn’t intended solely for Zero Retries - I think it’s a critical piece of info for promoting M17, and so it will be reformatted into a standalone article for posting to the M17 Project website. Why does this matter? Because with the success with the CS7000 M17 and CS7000 M17 PLUS (they’re selling…), I’ll guess that we’re about to see more radios coming out with “from the factory” support for M17. But the CS7000 M17 and M17 PLUS only implemented M17 voice - not data (as far as I have seen from their marketing material). If we don’t popularize M17’s data capability, and SOON, then the ability to use data in those new radios won’t be enabled. I hope that eventually using data on M17 will be as simple as connecting a USB cable or connecting via Bluetooth between a host computer (laptop, Raspberry Pi) and an M17 enabled radio and connect to the radio like a KISS TNC. Or something equally simple. The first radio to incorporate M17 voice + data will get the “full evangelism” treatment in Zero Retries that I gave the emergence of the CS7000 M17. My profound Thanks to those who accept my challenge. Steve N8GNJ --- Editor Zero Retries Newsletter -? Radios are Computers - With Antennas! |
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Funny you should ask this Steve. This week, inspired by SP5WWP's , I've started to look at M17 data, which is called Packet?Mode in the spec. It seems like it's kind of underspecified right now. The lower-level stuff?in Section 2.7 seems complete (although I haven't tried to use it to implement anything yet). Right now I'm focusing on the higher layers which say things?like "ATTENTION This is work in progress." There is some info there, but some things I can't quite figure out. There are some POC implementations, e.g. at and?, but it seems like it's still early days. Some of the puzzle pisces?are there, but some of the ones needed to build the system you'd want may not exist yet. Just to be crystal clear: None of the above is meant to be a criticism! Instead, it's more like an opportunity to get in early and help shape the capabilities going forward. Also, I'm new to this, so it's totally possible that I've just missed some of the things out?there. What I think I've learned: Texting currently is only over RF because there's no MMDVM, M17Gateway or reflector support for M17 Packet Mode yet. There's no OpenRTX support, so the only way to text with M17 is with SP5WWP's Nokia device or a 9600 baud capable radio with a modem, Digirig, etc. and some of the POC tools mentioned above. If there were gateway?and reflector support you could send and receive messages with anyone connected to the same reflector, rather than just the same repeater/hotspot. At that point it would be worthwhile to define routing--Tony VK3JED mentioned?D-Star's?ircDDB as a possible model.You could also build bridges to other messaging systems. The other thing necessary is application clients. It would be great if OpenRTX got a texting client so I could text with my CS7000. That's outside my area of expertise, so I'm working on a network messaging client POC--think Droidstar but for text messages (and not nearly as nice looking). That has also led me to look at the gateway/reflector piece. I'm starting to pick at those and hope to have something to show at some point. Keep in mind that when I refer to messaging above, I really mean M17 Packet?Mode data. If you solve these problems for texting, you can use the infrastructure to build lots of different applications. So someone should be thinking about what those applications could be and how they should work. Steve, I know you're good at envisioning that sort of thing, so I'd love to hear your thoughts! Hope this helps! Jim N1ADJ On Fri, Jan 24, 2025 at 2:18?PM Steve Stroh N8GNJ via <steve.stroh=[email protected]> wrote:
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I will try to find some time to catch up on the current state of M17, especially the packet modes being used. And I'll try to make a simple M17 texting app for Android and Mobilinkd TNCs. I'm pretty busy with other stuff at the moment. @SP5WPP was your packet mode code tested against or is compatible with either the Mobilinkd firmware or m17-cxx-demod? I had been thinking about the infrastructure bit, but I've been away from the M17 community for quite a while and don't know what the current state is. No one seemed particularly interested in packet mode at the time I wrote the spec. It would be nice to be able to send a "I'm here" packet that was sent to some global routing backend, along with the gateway that picked up the packet so that if someone somewhere else in the world wanted to text me, they could both know that I am listening and their message could find its way to me. But there is a lot to think about with this. It would be interesting to use the existing infrastructure for some of this. There is a global network for amateur radio use already in place. We would need to discuss with the APRS community. (I am a member of the APRS SIG.) It seemed to me that D*Star integration with the APRS infrastructure was a selling point for many of the early D*Star adopters. APRS is interesting because it should in theory be possible to message anyone in the world near an iGate (internet gateway) via APRS. APRS iGates send messages received over RF (APRS-RF) to APRS-IS, and any APRS iGate that sees a message over APRS-IS sent to a callsign that it has seen recently should transmit that via APRS-RF. Something similar can be used for M17 gateways. Do we need to worry about M17 amateur radio user infrastructure and M17 for non-amateur uses? If so, how do we do that? For example, we would not be able to use APRS-IS for anything but amateur radio. Do M17 text messages need to be acknowledged by the recipient? APRS has a messaging protocol that can request acknowledgement, and a retry protocol. This is typically enabled for terrestrial communication and disabled for space-based comms (e.g. anything sent via the ISS digipeater). Kind Regards, Rob Riggs WX9O Mobilinkd LLC On Fri, Jan 24, 2025 at 1:56?PM Jim Ancona N1ADJ via <jim=[email protected]> wrote:
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