Experimental Baofeng RD-5R version

[VK3KYY]

If I understood correctly, only the GD77 has separate PA for VHF and UHF. The GD77 works reasonably well when using the open firmware, therefore the correct PA is most probably used. If the wrong PA was used, we would not get reasonable results as to spectrum and power, yet we do.

There are still some finesses that need to be found out, as: "why does the ticking sound disappear when using the manufacturer's firmware on the same radio?", but they are relatively unimportant.

Again, if I understood correctly, the RD-5R uses one PA for the whole band. Yet, the open firmware does not work optimally on that radio. The power level is lower than expected and the spectrum adds spikes. The manufacturer found a way to operate the hardware which you did not find out.

I will solder some more wires to my GD77 "test" board today, to capture the data sent to the AT1846S RF chip during DMR Tx.
(This is not easy...)

Its possible that the official firmware controls some other values during DMR Tx.

Re: Ticking sound on the RD5R
This is probably caused by bad regulation of voltages in the radio, but somehow the official firmware limits the change to current and hence limits the noise because of bad voltage regulation.

PS. I think there is a schematic online for the FM radio which we think is similar to the RD5R, but I can't remember the model number of that Baofeng radio.

I will look on the github issues to see if I can find the name that the Russian Ham said was a similar (non DMR version)

[VK3KYY]

The thread is

https://github.com/rogerclarkmelbourne/ ... 7/pull/515

They think the FM only version on which the RD-5R may be based is the UV-5R

http://www.radioscanner.ru/files/downlo ... eng-5r.pdf

[VK3KYY]

I just had a look at the UV-5R schematic, and either the RD-5R / DM-5R are different, or the hardware is being controlled completely wrong.

The UV-5R looks like it only as 1 signal to control the band VHF or UHF, and another signal to control Tx and Rx.

I would be surprised if the firmware worked at all if the RD-5R / DM-5R was the same hardware, because the OpenGD77 controls separate Tx PA for UHF and VHF and also separate RF pre-amps

[do1jml]

Re: Ticking sound on the RD5R
This is probably caused by bad regulation of voltages in the radio, but somehow the official firmware limits the change to current and hence limits the noise because of bad voltage regulation.

There is no ticking sound on my RD-5R. Let me summarize my findings again:

Baofeng RD-5R
No ticking sound with either firmware.
WIth manufacurer's firmware: FM modulation appears to be OK. FM power level OK. DMR power levels OK. DMR modulation OK, but may be a bit distorted.
With open firmware: FM modulation with spikes. FM power level OK. DMR power level half of what it should be. DMR modulation bad.

Radioddity GD-77
With manufacturer's firmware: everything OK. No ticking sound.
With open firmware: everything more or less OK. Slight ticking sound.

[VK3KYY]

Re: Ticking sound on the RD5R
This is probably caused by bad regulation of voltages in the radio, but somehow the official firmware limits the change to current and hence limits the noise because of bad voltage regulation.

There is no ticking sound on my RD-5R. Let me summarize my findings again:

Baofeng RD-5R
No ticking sound with either firmware.
WIth manufacurer's firmware: FM modulation appears to be OK. FM power level OK. DMR power levels OK. DMR modulation OK, but may be a bit distorted.
With open firmware: FM modulation with spikes. FM power level OK. DMR power level half of what it should be. DMR modulation bad.

Radioddity GD-77
With manufacturer's firmware: everything OK. No ticking sound.
With open firmware: everything more or less OK. Slight ticking sound.

OK.

I'm not surprised.

[VK3KYY]

BTW.

The OpenGD77 updates the screen during Tx to show the mic level and also the talk timer, this may cause a small ticking on the GD77 and may be unavoidable.

The ticking and other noises on the RD5R are probably a product of some undocumented tricks with the AT1846S RF chip which we don't know

[do1jml]

The OpenGD77 updates the screen during Tx to show the mic level and also the talk timer, this may cause a small ticking on the GD77 and may be unavoidable.

That may be an explanation.

The ticking and other noises on the RD5R are probably a product of some undocumented tricks with the AT1846S RF chip which we don't know

I did not notice any particular noises on the RD5R with the open firmware. I noted that the power output was far too low, which motivated me to buy equipment to better measure it and post in this thread. Then you expressed worries about spectral components and I offered to check, to find out that the spectral output was not what was wanted.

I am not a specialist, but this is not likely to come from the AT1846S chip as we also have spikes in the DMR spectrum, and the AT1846S is not used for DMR, I think.

[VK3KYY]

The OpenGD77 updates the screen during Tx to show the mic level and also the talk timer, this may cause a small ticking on the GD77 and may be unavoidable.

That may be an explanation.

The ticking and other noises on the RD5R are probably a product of some undocumented tricks with the AT1846S RF chip which we don't know

I did not notice any particular noises on the RD5R with the open firmware. I noted that the power output was far too low, which motivated me to buy equipment to better measure it and post in this thread. Then you expressed worries about spectral components and I offered to check, to find out that the spectral output was not what was wanted.

I am not a specialist, but this is not likely to come from the AT1846S chip as we also have spikes in the DMR spectrum, and the AT1846S is not used for DMR, I think.

Thanks for the spectral analysis

It shows there are some problems with the firmware on both the GD77 and RD5R. Much worse on the RD5R which will definitely need some changes.

All weekend however, I have been working on some code instability problems with the firmware which affect all radios and cause the DMR Tx audio to completely fail.

Today (Monday) I will try to solder some wires to the AT1846S in my GD77 and capture the commands to that chip during Tx.

Its not practical for me to open my RD5R again, to attach wires to the AT1846S because I think I would break the radio.
In the manufacturing of the RD5R they glue the display and some other wires inside the radio, and to open it,I have to cut away the glue, and then after reassembling, I have to glue it together again, but I don't think I could do this again without causing some damage.

Hopefully just analysing the GD77 capture will give some more data.

The other alternative, to not opening the RD5R is to decrypt the official RD5R firmware, and then use Ghidra to attempt to find the function in the official firmware which sends the data to the AT1846S, then using the SWD debugger (JLink), it is possible to set a breakpoint on that function address, even with no source code, and then log the contents of the processor registers when that function is called.

However, this will probably take about 8 hours to setup, so is not my preferred option.


Also, some other people are looking at the small spikes of the power output on the GD77 and have some ideas about what may be causing this, and those ideas may be useful on the RD5R.



BTW.

Can you send me a link to the RTL-SDR spectrum analyser firmware you used.

[do1jml]

I don't understand the question about "spectrum analyser firmware". I used a stand-alone device.

[VK3KYY]

I don't understand the question about "spectrum analyser firmware". I used a stand-alone device.

OK.

My miss understanding... I thought perhaps you use some RTL-SDR software.

I have a TinySA but I've not used it very much.

I think there is some SDR spectrum analysers but I've not tried them.