[linux-dvb] Fwd: Re: Re: Types and capabilites for HDTV ATSC.

[Mac Michaels <wmichaels1@earthlink.net>]

On Thursday 05 August 2004 06:59 pm, John Dalgliesh wrote:
> On Thu, 5 Aug 2004, Holger Waechtler wrote:
> > I applied your proposed changes to the dvb-kernel CVS
> > frontend.h file. You probably also need to add a struct
> > dvb_atsc_parameters atsc to struct
> > dvb_frontend_parameters parameter union, right?
> >
> > It would then look like this:
> >
> >
> > struct dvb_atsc_parameters {
> > 	fe_modulation_t  modulation;
> > 	/* anything more? maybe 8VSB or 16VSB? */
> > };
> >
> >
> > struct dvb_frontend_parameters {
> >          __u32 frequency;
> >          fe_spectral_inversion_t inversion;
> >          union {
> >                  struct dvb_qpsk_parameters qpsk;
> >                  struct dvb_qam_parameters  qam;
> >                  struct dvb_ofdm_parameters ofdm;
> >                  struct dvb_atsc_parameters atsc;
> >          } u;
> > };
>
> Hmmm, shouldn't it be dvb_vsb_parameters not
> dvb_atsc_parameters? Or maybe atsc_vsb_parameters. After
> all, ATSC can also be carried over cable via QAM (right?
> I assume that is why everyone in the US wants cards that
> can do QAM (and I assume they don't convert the PSI to
> DVB))

I found an old 17 page paper "ATSC Transmission System: VSB
Tutorial" at
www.zenith.com/digitalbroadcast/downloads/VSB%20Tutorial.pd
f Figure 7 on page 7 has a nice VSB comparison chart.

It appears that 8-VSB for over the air in the U.S. is
 really called 8T-VSB. 8T-VSB uses Trellis coding.
 2/4/8/16-VSB do not use Trellis coding.

8T-VSB is used for over the air DTV in the U.S. 16-VSB is
for cable systems. From the paper it would appear that ATSC 
is a subset of VSB formats and not QAM. I am not sure of 
this though. Anyway, I agree with John that the parameters 
should be named dvb_vsb_parameters. There will be a small 
number of parameters because many parameters are identical 
between different VSB formats and can not be changed.

8T-VSB is robust in the presence of NTSC co-channel
interference but limited to 19.3 Mbits/sec. 16-VSB can do
38.6 Mbits/sec.

All the VSB data constellations use 6.0 MHz channel
bandwith, and  have a symbol rate of 10.762 Msymb/sec.

Best I can tell ATSC in the U.S  is 8T-VSB over the air and
16-VSB for cable. Since cable signals are not regulated by
the FCC some of them use QAM-64 or whatever they like for
DTV. A cable box is required for any scrambled and
pay-per-view services anyway.

The LGDT3302 chip can handle all 5 VSB formats and
QAM-64/256.

Mac Michaels