Proposal GD77 multimode + Web Transceiver

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ve2ugo
Posts: 32
Joined: Sat Nov 16, 2019 5:28 pm
Location: Quebec, Canada

Proposal GD77 multimode + Web Transceiver

Post by ve2ugo » Thu Aug 18, 2022 5:12 am

Since a member didn't appreciate that the topic inadvertently veered off to the GD77's functionality expansion capabilities instead of the original topic, we've moved the main points here for ease of research and discussion.

73 to all, good development and good discussion!
ve2ugo wrote:
Thu Aug 11, 2022 6:44 am
(...) It would be interesting if the GD-77 could serve as an interface to connect to the Raspberry Pi for communicate digitally via the Internet on various networks. It couldn't do it in RF given the architecture but could do it otherwise.
A bit like the Node-Ventures and the interface they created that will connect to the Raspberry with a speaker and microphone that will allow you to talk on various digital modes via the internet. We replace the module and take the GD-77.
The tools are already there with among others MMDVM_Bridge and Analog_Bridge from DVswitch.
It would just be necessary for the GD-77 to be able to talk to the computer and the radio could surely do even more without having to make heavy physical modifications.
An idea like that in order to make it evolve even more since it is itself limited, it will then need external tools to do even more in a radical way.

73!
ve2ugo wrote:
Thu Aug 11, 2022 8:21 am
Would it be possible to do then like a Node-Ventures but with just the DMR function in RX/TX but allowing multimode via the raspberry pi. It could thus in HotSpot mode have access to AllStar, Echolink, YSF, D-Star, NXDN and P25. The only thing is that the input and output will absolutely have to be DMR.
VK3KYY wrote:
Thu Aug 11, 2022 11:28 am
ve2ugo wrote:
Thu Aug 11, 2022 8:21 am
Would it be possible to do then like a Node-Ventures but with just the DMR function in RX/TX but allowing multimode via the raspberry pi. It could thus in HotSpot mode have access to AllStar, Echolink, YSF, D-Star, NXDN and P25. The only thing is that the input and output will absolutely have to be DMR.
The radio won't support any other digital modes than DMR because its call controlled via a dedicated DMR only chip.

FM is onl via direct paths from the mic to the RF chip and from the RF chip to the speaker

For DMR Tx the DMR chip directly modulates the master reference oscillator, all the RF chip does is produce what it thinks is a silent carrier, because its mic input is turned off.
For DMR Rx, the audio from the RF chip is routed directly into the DMR chip which does the complete decode into the high level DMR data, i.e the Source and Destination ID's and the audio byes etc.

There is no low level access to the decoded 4FSK inside the DMR chip and no way to tell it to modulate a 4FSK bitstream.
ve2ugo wrote:
Thu Aug 11, 2022 11:51 am
In HotSpot mode, the gd77 receives a dmr signal which sends it to the raspberry pi which is processed via a software suite, including mmdvm. This one does the routing or transcoding according to the command sent at the Pi-star for example. If I dial TG 71083 I communicate in YSF but i'm in dmr. The radio sends and receives in dmr only but transcoded in the desired mode via the raspberry pi. The flux will always remain dmr for the gd77.
By adding some modules, it is possible to add options like dstar, allstar and echolink. The mmdvm and other tools will do the dmr to ysf, dmr to p25, dmr to d-star but passing via internet and not rf.
The mmdvm and dvswitch will simply hook up and transcode the dmr stream to the desired mode.

It will not be possible to use any other radio with the hotspot than a dmr radio. It's clear. But transcoding the dmr in another mode via Internet surely...

The processing has nothing to do with the radio's internal chip. Everything could be done externally and sent in dmr to the radio. It would be a way to cheat to gain access to other modes and networks.
VK3KYY wrote:
Thu Aug 11, 2022 9:14 pm
There are already systems which will transcod the internet data to various other formats

But the radio can't transmit or receive anything other than DMR.
ve2ugo wrote:
Thu Aug 11, 2022 11:20 pm
VK3KYY wrote:
Thu Aug 11, 2022 9:14 pm
There are already systems which will transcod the internet data to various other formats

But the radio can't transmit or receive anything other than DMR.
Exactly! The gd77 will still be in dmr but it needs an external bridge to do the other modes. It may just need some firmware that could improve the experience in other modes.
So if it was possible to either use the gd77 in dmr to access other modes and networks via raspberry pi or to do the same thing in HotSpot then it would be a good solution.

In short, the idea is launched and the possibility of extending the functions of the radio into multimode or hotspot is upon us. It will never be multimode in RF but could provide access to several networks and modes via the Internet. This is one more possibility for the gd77.
VK3KYY wrote:
Thu Aug 11, 2022 11:38 pm
ve2ugo wrote:
Thu Aug 11, 2022 11:20 pm
VK3KYY wrote:
Thu Aug 11, 2022 9:14 pm
There are already systems which will transcod the internet data to various other formats

But the radio can't transmit or receive anything other than DMR.
Exactly! The gd77 will still be in dmr but it needs an external bridge to do the other modes. It may just need some firmware that could improve the experience in other modes.
So if it was possible to either use the gd77 in dmr to access other modes and networks via raspberry pi or to do the same thing in HotSpot then it would be a good solution.

In short, the idea is launched and the possibility of extending the functions of the radio into multimode or hotspot is upon us. It will never be multimode in RF but could provide access to several networks and modes via the Internet. This is one more possibility for the gd77.
There are already network gateways to the other modes. You just need to configure your MMDVMHost settings correctly
ve2ugo wrote:
Fri Aug 12, 2022 2:05 am
What about Allstar and echolink?

The way I explain it is that it would be possible to use it as a radio or hotspot in the same wayn without having to transmit. Mmdvm host does not connect to Allstar link, echolink or d-star. With this technique, it would be possible to integrate everything. No hotspot can transmit without rf with a microphone currently on all the networks that I have exposed.
Currently, if you have a gd77, you must either use it with a rptr in dmr or via a hotspot whether it is with a gd77 base or not. If the hotspot is mmdvm based, probably with pi-star, then you need an rf radio and a hotspot. These therefore require 2 equipment (hotspot and radio or radio and rptr). In addition, they do not do certain modes and cannot access certain networks.
With my proposal, the gd77 will be connected to the raspberry, will be able to access all the modes and networks but will also be able to communicate without the need to transmit in rf. So 1 equipment instead of 2 and the hotspot function would be maintained giving access to more networks. I think the principle offers greater flexibility with less mandatory equipment and need for rf...


I think this is an avenue that would be important to talk about again in order to really identify all the differences and possibilities.
VK3KYY wrote:
Fri Aug 12, 2022 6:14 am
You mean some sort of terminal mode.

In which case yes, but because you need to connect USB via the external speaker mic connections, people would need to make a special splitter cable and use an external mic

Hardly anyone would bother to make this device, so its adding this sort of functionality is not high on anyone's To Do list
ve2ugo wrote:
Fri Aug 12, 2022 9:12 am
Minimally, hotspot mode would have more networks and mode. It is already a lot! Everything would be software in the raspberry. No DIY!

Making a cable is already quite a bit more within the average capabilities of ham radio than making a hardware modification.

Using only the ptt of the radio and its microphone, could the signal also go to the raspberry? So there would just be need for an audio interface which the raspberry 3 or 4 could can be manage? Unless via firmware one can enable something else in certain situation?

The double idea is to allow to extend the functions of the gd77 by allowing to have access to more network in hotspot mode but also to be used in terminal mode (web transceiver) via the raspberry. The management of the ptt and the audio will be done such completely by the gd77, partly or via only the raspberry, I don't know since we are discussing it. You have to take some inspiration from the principle of Yaesu (PDN mode) with the ftm300/200 or FT5D (or CS-800D Plus, Node-Ventures) which allows you to go via the internet (web transceiver) without transmitting in RF but can also be used via hotspot or rptr.

More function, more mode (virtually all), more network accessible than with only an MMDVM (allows you to encode and decode your access, among other things to D-Star, YSF, P25, AllStar Link, Echolink, etc.) , no more way to join the amateur radio community using the internet via wifi, cellular, rj-45 or RF via the rptr and all this with a single radio instead of 2 minimum. A Hotspot which is also a ''web transceiver'' with access to all networks and modes. A beautiful project! Still interesting! And the tools are already available on the web to do this.

We are just discussing new possibility.

It is amateur radio which is made for experimentation and which is a technical hobby. I still think the possibilities need to be explored to make this as simple as possible but there will be a minimum of tinkering which is worth it to have access to all the networks. It's a first draft of an idea which is not meaningless... I don't think the idea should be discarded so quickly. Especially with the possibilities it offers.

There has been enough discussion here about the possibilities of extending the modes of this radio and which were not possible given the hardware limitation of the GD77. It is obvious that there is interest and it is the software part of the raspberry that must be worked on first!
If finally we have a possibility to do it completely via hotspot then I think that several would be takers. Thus, I think many would like to at least have a great hotpspot that would be able to give them access to everything! And if as a bonus the ''web transceiver'' function is there, then that would be great since we could do everything with a single radio and a raspberry pi with a little DIY which is part of the DNA of our hobby!
For once, a proposal is possible to have access to it...
(...)

If you want to participate in the project or add constructive and positive comments, you are welcome to continue the discussion thread.

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