HR2.0 - M17 Project - New Ham Radio Digital Mode

End-user radios are simpler, in particular power amplifier and TX/RX switching.

Actually not exactly.

You said 'the repeater pairs are already unobtainium in some places'. I definitively could agree however I don't really believe these places need more repeaters than already exist. These some places will probably loose from transiting to FDMA. Meanwhile there are many places where coverage ranges from poor to nonexistent as well as number of repeater users ranges from few to no one. There is no any need in such poorly covered areas to spit those few users into groups based on particular repeater, timeslot, anything else. I.e. poorly covered places won't benefit from two-slot TDMA itself; they could benefit from any repeater that could unite users. Still in terms of overage two FDMA repeaters apart are far better than one two-slot TDMA.

I love 'my' (my club's actually) two repeaters still I almost never ragchew on them (I personally not interested to participate local activity). Moreover there are many repeaters in my area (no pairs shortage problem there is regardless IARU region 1 entire 70cm band fits within 430~440MHz) and all they mostly have no any use: the more are repeaters the more spreads and thus fade local activity; with one single repeater this only one repeater in fact becomes the center of activity and involves everyone in listening for it. So I love 'my' repeaters for opportunity to practice with their antennas, RX splitter, TX combiner, etc. My buddies and I did a great work with setting them up and I proud to say our relays are not that pile of crap with slim rejection-only duplex filters anyone could put together and call it 'ham repeater'. We don't need amateur repeaters to be simple and cost-effective; we need them to make us to learn and to practice with them.

Anyway, all this is just my two cents. Any attempt to overestimate what I said could cause ineffectual dispute.

 

Because there are people volunteering to work on a project is a good enough reason for me. Shooting a volunteers spirit by poo-pooing their work or interests is a real bone headed move. Ham radio needs more tehnical people working on stuff, not less!

 

M17 alone is just another mode (just not incumbered), but the proposed proposed TR9 handheld I beleive will have a good selling point. And that is it will support more than just M17. That is something that the ham manufactures have not yet done. I think a lot of it is up in the air, but if a digital radio at a competive price that supports M17 and even just one other digital mode, be that DMR or D-Star, then I think the M17 project will be appealing to the end users.

I haven't paid much attention to the TR-9 radio progress, but I know they have secured a ARDC grant. I think there is an intermediate step for the quazi end user (the nerdier ones) to leverage the OpenRTX firmware project to help this gain a little momentum.

I'd would be nice if someone from the project would chime in, else they have their own forum for the curious: https://forum.m17project.org/

 

Sounds good.

73
Chip W1YW

 

Wow, that's easy, very informative. I wonder why that guy demanded email only instead of looking at the project forum and web site.

 

It’s just a hobby for me OM….so…

 

Whether the motivation is compensated or not, its all good.

73
Chip W1YW

 

Probably give him some sense of impotence ... uh, importance.

 

All of this fuss amuses me. If it contributes to the advancement of the radio art, it's a legitimate ham radio effort. Let a million protocols bloom!

 

Actually, it is.

For example, on one of my ham systems, we have two different radio clubs utilizing the system, one assigned to TS1 and one assigned to TS2. There is 1 repeater, 1 antenna, 1 radio site, yet 2 completely separate groups utilizing the 12.5 kHz of bandwidth using the same equipment. I have several similar setups on the commercial side of things. TS1 is used for 1 group, TS2 is used for another. The only other way to accomplish something similar is with trunking.

If I were to use FDMA, NXDN, for example. I would need 2 completely separate repeaters for each of those systems. This is exactly why DMR makes so much sense.

And quite frankly, the future is going to be Extended Range Direct Mode (or similar), where a DMR system can operate on a single frequency, without needing a pair. You lose the ability to use both timeslots, but you gain an extra frequency, since a pair is no longer needed. I have tested it extensively, and it works incredibly well.

 

Why not? The problem is that the bandwidth is being completely wasted by 25 kHz wideband FM. Using TDMA, you could essentially have 4 talkpaths in that 25 kHz of bandwidth, instead of just one. Even narrowbanding would solve much of the issue, but no, nobody wants to give up their old crappy Master II repeaters.

Of course that isn't the case everywhere. But in those places, FDMA makes no sense. If you want some sort of "standard" that everybody is going to use, it isn't going to be FDMA, that I know. It just makes no logical sense.

 

Because we, radio amateurs, could take almost any radio we've got, then connect it with homebrew or ready made hardware, or with a computer running amateur software emulation of the hardware, and operate that Digital Voice we're discussing. With TDMA we'll be pretty limited by particular radio RX/TX switching speed. Any attempts to accommodate wider guard intervals will cause less data per bandwidth efficiency so this way will lead us to the dead end.
And because time slots are synced with a repeater by a repeater. Amateur radio is not limited by a repeater; direct contacts still are popular. Sure TDMA itself could allow full duplex on physically same frequency but does any existing DMR radio allow full duplex? Does demand on full duplex exist among ham OPs? I'd suppose both questions have to be answered with hard 'no'.

You count just right. Two timeslots per one 12.5kHz channel are four times more efficient than one 25kHz channel. So do I: two 6.25kHz channels are equal to one two-slot 12.5kHz channel. If only we're talking about repeaters sharing common antenna. If we're going to physically split one two-slot 12.5kHz repeater to two one-slot 6.25kHz repeaters i.e. to build two independed repeaters apart we'll gain in coverage up to two times within same spectrum.

No one will be forced to shut down their TETRA (four timeslots) repeaters in favor of FDMA. Still benefits of TDMA in fact are not so valuable for many areas where amount of OPs is equal to zero plus-minus measurement error.

Logical sense is that the OP could take almost any radio and almost any amp but not specially designed like DMR, TETRA, GSM, etc.

I'm not objecting the assertion that TDMA has advantages over FDMA as these advantages are obvious. I only assert FDMA still has advantages over TDMA too, in particular simplicity of modifying almost any existing radio to DV-capable.

 

BTW why nobody complained new project didn't focus on something like OFDM that is much more efficient than 4FSK (GMSK, etc.)? Or why wouldn't developers take QAM?

 

Absolutely not! I already have a hard time recognizing the "sound" of a digital protocol. Yes, I can recognize FT8 and PSK31 but all the other "umpteenth-frequency/phase" modes are quite hard to recognize otherwise than by their used frequency, if at all standardized. Ever tried to switch to all possible modes and derivatives in FLDigi when you hear an unknown signal? By the time you tried them all, the QSO is long gone. Even simple FSK uses several bit counts, bit rates and shifts. Too many possible combinations.