[linux-dvb] DVB-S with CI card to buy

[Kenneth Aafløy <ke-aa@frisurf.no>]

On Friday 11 June 2004 23:19, Ragnar Sundblad wrote:
> --On den 11 juni 2004 22:01 +0200 Kenneth Aafløy <ke-aa@frisurf.no> wrote:
> > So was the crappy power-supply the root of all your troubles, or have you
> > had  other problems as well? I guess the cards ain't some kind of magic
> > device  which can filter away noise from a crappy psu, hmm? Keep in mind
> > that it's  receiving fairly high frequencies, and noise is not it's best
> > friend.
>
> There is absolutely nothing magic about filtering power supply
> lines for analog sections of computerized devices.
> Actually, it is what such devices have to do, but doing it
> right is not that easy.

I have not read the AT-X spec, but I belive that it sets some limitations on 
how a PSU should behave, and the people might have found that the card they 
designed was on the edge of tolerance, but chose to push the card to 
production regardless. The question if this is the case, which is pretty 
obvious to me is who is to blame? The card producer that makes a card that is 
borderline or the maker of the PSU which obviously has to be out of spec?

> That is not the only problem with those cards;
> My DVB-T FF card has an impedance mismatch between the tuner
> and the demodulator that most probably explains why its
> reception is so much worse than my set top box.

Are you saying that the manafacturer used a lot of bad components on this 
board, or just that they put in the wrong capacitor?

> The same card has waves traviling over the screen on the
> composite out. Probably a power distribution/filtering
> problem. It seems that most or all DVB-T FF cards has that.

It sounds like you are getting the frequency of the power grid out on the 
composite output, at least in this context.

> My DVB-T budget's tuner broke after about 6 months (how often
> do tuners break (if not struck with lightening)?).

There is always the person that has experienced the bad hardware that 
sometimes slips through testing, I bet that if we got word from all those 
that had experience with a bad card versus all people that has never had a 
problem with their card dying (not software related) it would indicate a low 
amount of failures. You did get a new card, hmm?

> It seems that there are much less problems with the DVB-S
> than the DVB-C and especially the DVB-T cards, I guess because
> there are intergrated tuners and demodulators for DVB-S which
> handles most or all of the analog considerations in a tin box.

So the DVB-C/T cards does not have a ground shielded tin-box?, now is not that 
just lame design, the cards receive frequencies around what DVB-S does (at 
least after the LNB did it's job), and definatly higher than VHS+ :) or?

All in all DVB-S cards are good, DVB-C/T cards are bad? ;)

I can however go good for my Hauppauge Nexus-S, as a premium buy, as my only 
problem was that motherboard that did not follow specs, which is very rare.

Kenneth