Kbtv2 beta2 uploaded
danny at ricin.com
Sun Feb 24 23:57:11 UTC 2008
On Friday 22 February 2008 18:59:44 Dieter wrote:
> > > > Your card seems to have a microtune tuner mt2050 which is not yet
> > > > supported by the saa backend. I'm looking into it. Unfortunately it
> > > > differs from the other generic tuner APIs for saa in that tuning and
> > > > init are to be handled differently (mt2032 is supported by bktr, so I
> > > > can peek there). THis is an important tuner to have support for
> > > > though for several reasons:
> > > >
> > > > - it's on a chip, not in a large chunky metal enclosure
> > >
> > > I have read that the very small USB tuners don't perform as well as the
> > > "large chunky metal enclosure", because some features were left out.
> > Well, they don't have an mpeg encoder chip, but neither do the old
> > fashioned analog TV cards. Of course, supporting that A/V decoder is
> > another matter. But so is supporting an onboard mpeg encoder.
> > They seem to use empia chipsets almost exclusively, the variant without
> > onboard MPEG encoder is called the "blackbird" design IIRC.
> No, I mean the reception performance, not mpeg features. The "big" metal
> cans supposedly have better RF filtering. Keeping the undesired
> frequencies out is important.
I've been looking into how they work and what they do is they have two IF
stages. They demodulate to higher frequencies first (order 1200 MHZ) then do
the usual demod to actual IF (for PAL, ntsc, but also QAM etc). Supposedly
this makes it possible to discard a lot of noise. That's how they can make
the chip useful for so many types of applications (including mobile). So it
has two seperate PLL loops with the same crystal for reference signal. At
least , that's how I understand it so far. I'm not done studying it yet.
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