[linux-dvb] QAM 256 starts kicking out VDR widespread TT/FuSi FF cards / on AGC, etc, IMPL and Filter Optimisation

thomas schorpp t.schorpp at gmx.de
Sun Aug 6 21:27:11 CEST 2006


thomas schorpp wrote:
> thomas schorpp wrote:
> 
>> thomas schorpp wrote:
>>
>>> Marco Skambraks wrote:
>>>
>>>> hi,
>>>>
>>>
>>>>
>>>> any ideas?
>>>>
>>>> marco
>>>>
>>>
>>> no.
>>>
>>> and the other devs seem to be in holidays or have no more interest in 
>>> older FF cards.
>>>
>>> ill do trial'n'error with the filter registers or implement 
>>> sysfs/procfs support in ves1820 for a trimmer GUI until I get access 
>>> to professional mesurement equipment.
>>>
>>
>> ves1820 driver has DFE (decision feedback equalizer) set to off, 
>> however web literature states this should be the better method than 
>> just transversal.
>> ill try it.
>> and there more ideas from the stv driver code.
>>
>> tom
> 
> 
> DFE brings no qam256 relevevant improve, too:
> 
> static u8 ves1820_inittab[] = {
>     0x69, 0x6A, 0x93, 0x12, 0x12, 0x46, 0x27, 0x0A, // 06 46 //07 1A
>     0x43, 0x6A, 0xAA, 0xAA, 0x1E, 0x85, 0x43, 0x20,
>     0xE0, 0x00, 0xA1, 0x00, 0x00, 0x00, 0x00, 0x00,
>     0x00, 0x00, 0x00, 0x01, 0x32, 0x00, 0x00, 0x00, // 1C 00, 1E 00
>     0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
>     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
>     0x00, 0x00, 0x00, 0x00, 0x40
> };
> 
> no more much software optimization left. the stv code's "software filter 
> regulation" cannot be easily adapted for now, too, the better DFE is 
> hard to configure without using hardware testmode and lab equipment, and 
> i dont believe in "matlab" simulations.
> 
> next trying to hardware chain missing ves1820 VAGC -> IF chip's extern 
> AGC input or bypass if chip completely (at cost of analogue tv support).
> 
> CD1516 tuner is also suspect to degradation, design mismatch and so 
> replacement with a more modern device.

done. no success.

proposed resolution:

according to datasheets and kabelbw.de provider device-blacklist 
only tda10023 and newer supports latest dvb-c standards used 
by some providers.

-> WONTFIX

y
tom




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