A couple of newbie questions

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K0WKA
Posts: 2
Joined: Fri Jan 06, 2023 5:33 pm

A couple of newbie questions

Post by K0WKA » Fri Jan 06, 2023 5:52 pm

Hi guys. A newbie here, not that much of a ham (although callsign is real), just love meddling with things. First post here, have couple questions that better belong to other sub-forums, hopefully someone would see them...

1. I'm very excited about TYT MD-UV380 alpha firmware. Question - are the sources currently available? Any chance to see them and possibly to contribute?

2. Probably a question to Roger - The F.A.Q. states that SFR repeater mode is impossible to implement on current hardware (specifically C6000/AT1846S). Why???
The C6000 datasheet explicitly claims support for SFR repeater mode AND full duplex mode as well. My understanding is that we just have to switch transceiver from rx to tx on timeslot interrupt (and we have the whole 2.5 msec to do this). What's the problem?

Thanks in advance!

VK3KYY
Posts: 7484
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: A couple of newbie questions

Post by VK3KYY » Fri Jan 06, 2023 7:43 pm

K0WKA wrote:
Fri Jan 06, 2023 5:52 pm
Hi guys. A newbie here, not that much of a ham (although callsign is real), just love meddling with things. First post here, have couple questions that better belong to other sub-forums, hopefully someone would see them...

1. I'm very excited about TYT MD-UV380 alpha firmware. Question - are the sources currently available? Any chance to see them and possibly to contribute?

2. Probably a question to Roger - The F.A.Q. states that SFR repeater mode is impossible to implement on current hardware (specifically C6000/AT1846S). Why???
The C6000 datasheet explicitly claims support for SFR repeater mode AND full duplex mode as well. My understanding is that we just have to switch transceiver from rx to tx on timeslot interrupt (and we have the whole 2.5 msec to do this). What's the problem?

Thanks in advance!

1. Firmware is only at ALPHA level. Sources don't get released until a fully stable Release version is reached
2.SFR is limited by the RF hardware, not the C6000. It take too long for the AT1846S RF chip to switch between Tx and Rx :-(

I am not sure what C6000 data sheet you are referring to, it may be the hacked version someone sent me that they bought via a Chinese hacker website. If so, I would not that it, as the data sheet us not 100% accurate.

There is no publically available official data sheet for the C6000, And there isn't a full public data sheet for the RF chip either.

We have to mostly rely on doing data captures of internal data bus transfers when running the official firmware on each of the radios, and strangely we can't even use exactly the same C6000 configuration commands in each radio , despite them having the same chips.

E.g. the UV380 would not receive DMR if we used the same C6000 as in the GD77 or MD9600

It would take hundreds of hours of effort to attempt to understand this, with no actual change to the operation of the firmware, so it remains a mystery

K0WKA
Posts: 2
Joined: Fri Jan 06, 2023 5:33 pm

Re: A couple of newbie questions

Post by K0WKA » Mon Jan 09, 2023 1:16 pm

VK3KYY wrote:
Fri Jan 06, 2023 7:43 pm
I am not sure what C6000 data sheet you are referring to, it may be the hacked version someone sent me that they bought via a Chinese hacker website. If so, I would not that it, as the data sheet us not 100% accurate.
Same one as you have, I guess - https://github.com/OpenRTX/OpenRTX-exte ... slated.pdf

VK3KYY wrote:
Fri Jan 06, 2023 7:43 pm
2.SFR is limited by the RF hardware, not the C6000. It take too long for the AT1846S RF chip to switch between Tx and Rx :-(
I don't get it. I'm not flame-baiting, I honestly don't understand why. Assuming that we are in SFR repeater mode, switching from RX to TX and vice-versa requires:
1. Enable/disable related PAs
2. Configure tx PA gain DAC
3. Write single AT1846S register (030h) over I2C

And we have just above 2 ms to do all three.

(1) and (2) are instant, (3) is a 3-byte i2c transaction, with 100khz bus we are perfectly within our time budget. And even if we were not, nothing can stop us from sending i2c transaction in advance, so register update happens in time, during 2ms timeslot transition.

The current GD firmware does a lot more on rx/tx switch, but all of it (like programming frequencies and long rx off - update - tx on transitions) is not needed for SFR.

I wonder if it is really the case, that AT1846S takes more than 2 ms to stabilize after register update? Did anyone measured that? Or is just a matter of programming?

I'll beat it, if it is a dead end, but if there is any chance I'd like to get SFR repeater working on this hardware...

G4EML
Posts: 919
Joined: Sat Nov 16, 2019 10:01 am

Re: A couple of newbie questions

Post by G4EML » Mon Jan 09, 2023 5:40 pm

Feel free to give it a try if you have the time. It would be great if it could be made to work.
Both Roger and I came to the same conclusion, after doing some independent preliminary tests, that the 1846 chip takes too long to stabilise after switching from Tx to Rx to be able to do this. I can't remember the results and there is no real published data for this but as the chip was originally designed for very low cost FM handhelds it would not have been designed with this in mind.

Some recent Chinese radios have SFR support. The common factor is that those that offer SFR all seem to have duplicate receiver and transmitter hardware. That probably means the receiver can be left active while the transmitter is keyed on and off.

Colin G4EML

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