[chirp_devel] Mode designator for YSF?

[Mathias Weyland]

On 2023-01-11 00:13, Dan Smith via chirp_devel wrote:

Hello

Reading what I just wrote during the past hour or so, there is a lot of 
technical details that may be boring to say the least... Thus you may 
want to scroll to the end where I tried to address the solution that you 
proposed, which is quite good IMO.


> The manuals for those radios seem to indicate that the
> behavior on the radio itself is the same, but I can't figure out why
> their software won't let you choose that. And, even though I can
> select VW in a separate place in the radio, the FT3 software seems to
> have zero mention of it.

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? 
Another idea may be to look at another third party programming software 
made by RT Systems and check if they added the functionality...


> Is it possible that Yaesu just didn't
> implement knobs for the digital settings in their new (at the time)
> flagship digital radios?

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...


> Seems to me that "AMS" is really a behavior of the radio

That makes a lot of sense.


> 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. 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.


> And especially since you don't control whether you receive VW or not 
> (right?)

Correct, that was confirmed by Charlie earlier tonight.


> How prevalent is the real-world usage [of VW]?

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...


> However, users looking at their radio, manuals, and Yaesu's own
> software will likely not intuitively know what it means.

This is a good point. Everything I wrote is based on the technical 
details and not necessarily on how people use their radios and software. 
I should add that I was involved in reverse-engineering the missing 
parts of the YSF protocol when it was launched. My interest in YSF was 
mostly in this regard and I have not used any of that in practice...


> trainwreck

... aye ...

> 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.


> So I guess it seems like if we add a DN mode to mean
> "Yaesu's C4FM format" and then flags for AMS or VW (with a default to
> Yes and No respectively), that's the right behavior, and keeps
> DN-supporting radios speaking the same language.

I guess that does make sense. What about the following scenarios, 
though:

- 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...

- 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..

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

Matt