[chirp_devel] Mode designator for YSF?

[Dan Smith]

> That seems odd indeed. Then again, Yaesu made quite a number of very odd choices when it comes to Fusion... What happens if you select and store VW on the radio and read out the memory? Does it have the VW flag?

This is what I'm saying I haven't done yet. I decoded more of the unknown flags last night (which I merged a bit ago) which will help cut down on the things I need to look for. But yeah, I will do this. The way the radio presents it, it might be a global thing and not per-channel, I'll just have to see.

> That is possible in the light of what I wrote above... There is also the following tidbit that may have affected such decisions: VW and DN differ from each other in three fundamental ways. One is the way the metadata and the digital voice is multiplexed, as mentioned in my previous E-Mail. The second one is how the digital voice frames are processed and turned into the bit sequence that is actually transmitted, e.g. how and what kind of redundancy is added, how the digital voice bits are scrambled, block-interleaved etc. (although "DN" by itself has two ways of doing that...), and by the way the voice is encoded into the speech model representation. While both DN and VW use the same fundamental speech model, they differ in the number of bits that are used to encode the various parameters of the model. These models and encoding schemes are proprietary and you can buy chips to transcode from PCM and back. Two details are interesting about this: (a) The DN type is actually the same as the one used by DMR (but not stipulated by the DMR standard). This is why it is easy to write software that bridges between DMR and the YSF DN flavour. Also, there is no loss of quality due to transcoding, since you don't have to decode to PCM and re-encode. "VW" may have dropped out of favour because it is (was?) not supported by those bridging solutions. (b) the  common chips that you can buy to convert back and forth actually do not support the "mode" used in VW. Yaesu licenses some DSP IP to do that, but this is not something you can do in low quantities, thus there is no easy/legal way for us to homebrew receivers that fully support YSF. While I don't think that Yaesu cares about that, they may have come to the conclusion that it was not smart to use that "special" thing for VW and backtracked a little? Who knows...

Wow, yeah. It sounds to me from the above (correct me if I'm wrong) that maybe DN encompasses two things, sort of layer 1 and layer (or 7). Layer 1 being the lowest protocol and Layer 7 being some of the voice/data/codec stuff , and that VW mode would reuse a lot of layer 1 but swap out more of the Layer 7 stuff than just "twice as many voice packets" (so to speak). Maybe?

>> Further, "VW" doesn't seem like a mode to me. It's still the same modulation,
>> but with more voice data and less data data, more akin to transmit
>> bandwidth on an HF radio or something.
> 
> I would disagree with that statement but without drama. My disagreement is because of the technical detailes outlined above.

Yep, I'm seeing...

> The differences are much more substantial than just a matter of bandwidth. Yes both are 4FSK, the air packets have the same preamble and header, and indeed they use the same fundamental speech model, but everything else is different. In an odd way, DMR and DN are more similar to each other than DN is to VW. Does that make DMR and DN the same mode? Then again, my point is based on the technical implementation of those things and that may not be what people care for or what makes for the best implementation decision in chirp.

Right okay. So I still want to call DN the mode (in terms of what CHIRP needs, layer 1). And I guess say that there's also a DN/VW switch for Layer 7. I know, I'm making up layers.

> I have no idea :-). Also there may be regional differences so any particular answer may be biased. Still the solution you proposed below seems like a sensible one to me...

Ack, cool.

>> trainwreck
> 
> ... aye ...

/me screenshots for later.

>> I kinda wonder  if that activity would be a cacophony of people in both modes not
>> really realizing when they're digital or not. Is it actually better in
>> practice?
> 
> The difference is pretty clear by the presence of noise vs. the robotic nature of digital voice. There have been issues with people not having AMS turned on and transmitting on top of ongoing contacts because they failed to realize that the frequency was in use. Also, at least some radios disable AMS when you establish a networked connection ("WIRES-X") which adds to the confusion. I practice, YSF has been mostly a novelty thing around here, people try it after purchasing a new radio and then quickly lose interest, for the most part.

Yeah, I'm sure you can tell the difference. What I mean by cacophony is in terms of the chaos (as you describe) and the wildly different sounds when you're expecting one or the other :)

> - Would there be a difference between 'FM' plus AMS checked and 'DN' plus AMS checked? Because according to this logic, that should be the same setting. How would we deal with people who program FM & AMS and once they read back their programming, chirp displays that as DN & AMS (or vice versa)? Would that cause confusion? Would users know what to select if they actually want the AMS setting? I wouldn't really know if I had to select 'FM' or 'DN' along with the AMS checkbox to get that...

Well, first let me say that CHIRP is an abstraction, and as such, we have to make some concessions in the name of compatibility.

But, what I've got going right now is that selecting "FM" will turn off DN and AMS, the equivalent in Yaesu's software to selecting "FM" and "Analog" in the "Analog/Digital" column. Selecting "DN" will enable AMS, the equivalent in Yaesu's software of selecting "FM" and "AMS" in the "Analog/Digital" column. Setting AMS and/or VW when the mode is "FM" or "NFM" or "AM" won't do anything. That way if you copy and paste an FM channel from a repeater directory or another non-YSF radio, you'll get an analog channel that won't try to auto-mode you into anything.

> - What about the combination FM, no AMS and VW? That would not make sense. Is there a way to gray out the VW checkbox in that case? Then again, this may be similar to the RX-Tone column when TSQL is not used..

Well, I'm not planning to actually expose these as columns in the main editor, but options in the RightClick->Properties dialog, like D-STAR stuff is now. There's no rules-based stuff in there to grey out certain things when others are set, mostly because that's like a "tell me what you want it to look like" sort of interface. Thus, no tone mode based hiding of fields in there. But that could change in the future.

> I hope that helps, and apologies of the verbosity of my post

Don't apologize, verbosity is what I was looking for :)

So what I've got so far is this:

https://github.com/kk7ds/chirp/pull/376

Which allows me to trivially select FM and DN with the above "probably what most people want" defaults, and to import YSF repeaters from repeaterbook. I haven't implemented the toggles for disabling AMS (but keeping DN on) or VW yet.

--Dan