Re: Afatech af9005 unstable reception [added: mt2060 gain control?]

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En/na P. van Gaans ha escrit:
My last question for a cheap USB DVB-T stick took a whole other turn. Earlier I bought an Allnet all2006 USB DVB-T stick, just praying it would run on Linux. It didn't. At least it didn't back then.

On Windows I figured out it's an Afatech AF9005 clone. On Google I figured out there is a driver and firmware here, recently written: http://ventoso.org/luca/af9005/

Happy was I! I installed everything and yes, the device is detected. But it hardly ever locks correctly on a frequency. I see the "lock" thingie in Kaffeine light up, as well as a blue led on the stick. But few times do I read some channel information. Once I was able to read the radio transponder, but the radio stutters. That doesn't really say much, radio stutters with another DVB-T device on Windows as well at that frequency, and I have no idea if my reception or buggy software is the problem here.

The main problem is I can't read all channels. I'm missing almost all the channels. The -/+167 trick didn't help.

Well, I found that reception with this stick isn't very good, but since it does the same under windows (actually under Linux I can catch more channels) I thought it was just a problem with the hardware. OTOH I have other users reporting that the stick works just fine for them. Maybe it depends on the tuner used (I have an mt2060, others have a qt1010) or on the overall quality of the stick (there are various no name ones using this chipset and the terratec cinergy xe). If you have a stick with an mt2060, there's a commented out section of code that tries to reduce the gain of the mt2060 if the demodulator detects a strong signal. I tried it talking directly on the i2c bus with the mt2060, since the mt2060 code doesn't provide such an option (maybe one of the tuner ops should provide for gain adjustment?), but since I saw it didn't make a difference here (and I live pretty close to the transmitting tower) I just commented it out. You can however look in the logs (enabling at least debug=1) for messages "adjust for strong signal 1". If you see them you can try to uncomment the code in af9005-fe.c (look for the comments "adjust mt2060 for strong signal (test)").

Bye
--
Luca

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