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[linux-dvb] Re: VES1820.c question
Hi,
Dennis Noordsij wrote:
> Hi,
>
> This is a question in response to Marko Kenttälä's patch for VES1820.c to
> allow QAM_128 tuning using a Siemens DVB-C card (QAM_128 is needed for
> Finnish channels).
>
> Specifically these lines (NEWSTRUCT branch by the way):
>
> 246 QAM_SETTING QAM_Values[] = {
> 247 {QAM_16 , 16, 145, 164, 162, 145},
> 248 {QAM_32 , 32, 150, 120, 116, 150},
> 249 {QAM_64 , 64, 106, 70, 67, 106},
> 250 {QAM_128, 128, 126, 54, 52, 126},
> 251 {QAM_256, 256, 107, 38, 35, 107}
> 252 };
>
> The last 4 values of each setting refer to registers 1, 5, 8 and 9.
>
> However, the same values are used for registers 1 and 9, whereas the datasheet
> specifies the following values for register 1:
> QAM_16: 140
> QAM_32: 140
> QAM_64: 106
> QAM_128: 120
> QAM_256: 92
>
> Now, I understand there can be a million reasons why the sourcecode does
> something else, and I wouldn't know any of them, but the reason I am asking
> is that in order to tune to QAM_128 (remember Siemens DVB-C) Marko discovered
> register 1 should be set to 120 instead of 126 for QAM_128.
(Hmm, I'd suppose a typo which did not showed up in our tests:)
Unfortunally we have only QAM_64 transmissions here, and there the value
was correct...
> Which brings the
> question, why does a different value than the datasheet work for for example
> QAM_64, but not for QAM_128 ?
For QAM_64 values in registers 1 and 9 were equal (106).
Holger
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