Twinhan 3250 tuner works great in Windows, only half channels in Linux?

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EFM6
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Re: Twinhan 3250 tuner works great in Windows, only half channels in Linux?

Post by EFM6 » Sun Aug 02, 2020 3:59 pm

It's the newest Kubuntu LTS. 20.04. Terminal says the kernel is 5.4.0-42-generic.
Previously this week I've tried various other LTS versions of Ubuntu and Linux Mint, (mostly just for fun since they're all similar underneath).

Now that you mentioned it, it does make me wonder if, not a new kernel, but if an old kernel has a fully-working driver for the Twinhan card. That seems unlikely, but why would people create the driver years ago but then it doesn't work on channels below 21.

And I wonder more about an old driver working because in Windows the Twinhan only works with 32-bit. In the past, I've tried every modified Twinhan driver I could find, tried installing them with every "install in compatibility mode" option, etc, and never got the Twinhan working in Windows 7 64-bit. I know (only one card, not two at the same time) works in Windows 10 32-bit. Haven't tried Windows 64-bit yet, though I assume it won't work.

MythTV is recording some shows today. After those, I'll try the newest kernel and some older kernels. Apparently, Linux can change it in Terminal without needing a format and reinstall, so we'll see how that goes. And also will try a 32-bit version of Linux. Who knows, might get lucky.

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Re: Twinhan 3250 tuner works great in Windows, only half channels in Linux?

Post by wesnewell » Sun Aug 02, 2020 5:43 pm

If you want to try different kernels I'd suggest installing ukuu. sudo apt-get install ukuu. That will allow you to easily try as many kernels as you like, old and new. Another option would be to compile your own kernel from source, after modding the bttv driver source.
BE/FE-Asrock AB350 Pro Ryzen 3 3200G, 6 atsc tuners. FE's-GF8200's Athlon II, Ryzen 3 2200G. Mythtv user since 2005.

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kmdewaal
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Re: Twinhan 3250 tuner works great in Windows, only half channels in Linux?

Post by kmdewaal » Sun Aug 02, 2020 7:20 pm

The problem here is most likely more than just changing a constant. Writing and fixing tuner drivers does require the chip documentation and low-level debugging capabilities. There have been enthusiasts who have written Linux drivers by reverse-engineering the way a chip has to be controlled by capturing and analyzing the I2C traffic that is generated by the Windows drivers.
I do recall programming a DVB-T tuner chip that had four VCOs (voltage controlled oscillators), each VCO for one part of the tuning range. It is just guessing on my side, but it could be that the people who wrote the driver for this Twinhan have found the VCO for the frequency range starting at 510MHz but they have not found the other VCOs.

EFM6
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Re: Twinhan 3250 tuner works great in Windows, only half channels in Linux?

Post by EFM6 » Wed Aug 05, 2020 6:04 am

grrr....

Spent hours trying to get a fresh install of MythTV to work. Add user problem. Then can't connect to database problem. etc.
Messing with MySQL, looking in config files for passwords and host addresses....
Then realized I was trying to install version 29, which I had read was later updated so newbs like me could install Myth easier.

Due to the difference in 32-bit and 64-bit Twinhan drivers in Windows, I had to know if there might be a difference in Linux too.
But there are few 32-bit distros now. So I installed an older 18.xx Ubuntu.
18.xx is of course set to use repositories for MythTV 29.

After realizing that, installed current version 31 like I had been.
The Twinhan still didn't scan the lower channels. oh well. Had to try.

Ukuu helped. Not sure if I would have tried different kernels without it. Though can't just install the default anymore since it's now a paid version. But can still find older versions. Different kernel didn't affect the Twinhan.

And, yeah, there isn't much chance of compiling my own kernel or reverse engineering anything since a week ago I didn't even know what a sudo command is.

I assume the VCO, frequency, etc, values could be seen in the Windows driver, but I'm giving up now on them fully working. Thanks again. It would have been nice if these cards fully worked, but they do at least half work.

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