[linux-dvb] Current state of DVB-C support

Christian Lyra lyra at pop-pr.rnp.br
Fri Apr 17 21:33:54 CEST 2009


Hi there,

	I´d like to share with you my recent experience with DVB-C cards and a 
Brazilian Provider.
	
	My first attempt to use a DVB-C was with a KNC1 card. I just had to 
download the latest source from dvb repository, compile and install. 
The card was identified, I could scan channels and watch TV. BUT some 
channels works very badly, as the card couldnt lock properly on a few 
transponders (309mhz and 321mhz). Running a czap on those channels 
shows that the card keep "locking" and loosing the lock.
	I thought that the problem could be something with my cabling, so I 
tried my card at a friend´s house with the same results. I also tried a 
attenuator, but without success too.
	  
	On my second attempt I bought a twinhan CAB ci card. Card identified, 
but scan didnt worked. Some googleing later, I got it working by 
commenting the line 1360 in dst.c (!(state->dst_type == 
DST_TYPE_IS_CABLE) &&). To my surprise this card has NO problem locking 
on 309mhz and 321mhz channels. It seems to take a little longer to 
lock/changing channels compared to my twinhan DVB-S card (I´m comparing 
apples and oranges, right?), but so far it´s working ok.

	My third attempt was with a technisat cablestar HD2 card. I used the 
mantis repository to get the card working (is the mantis driver already 
merged with v4l-dvb?). Again, I can scan channels, but the card could 
not  lock on those Transponders. In fact it also take a lot longer to 
lock on a channel, but after it got a lock, it works right.

	Since twinhan works fine, I supose that there´s no problem with my 
cable/splitter. Also, I supose that the chance of two disctinct broken 
tuners is low. A recent thread on TT-1501 shows that, if I understood 
it right, there´s a kind of table where a power level is set to each 
frequency range. Is it possible that my two cards didnt worked on those 
especif transporders because of this kind of setting? 

	I´m not a dev, but I would like to help to debug this. How can I help?

-- 
Christian Lyra
POP-PR - RNP



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