[linux-dvb] VES1820.c question

[Dennis Noordsij <dennis.noordsij@wiral.com>]

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. Which brings the 
question, why does a different value than the datasheet work for for example 
QAM_64, but not for QAM_128 ? 

The code was written by Ralph Metzler, but the answer is probably so simple I 
don't want to bother him with it :)

Just curious, I do not pretend to know any of this stuff :)
thanks
Dennis

PS I am looking at this in anticipation for using the Siemens card, I don't 
have one yet so I can't test it.



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