[opendtv] Re: Toward digital TV

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 15 Dec 2005 18:34:29 -0500

Bob Miller wrote:

> But COFDM DVB-T was more robust at a higher bit rate
> than possible with 8-VSB in 2000 as demonstrated by
> Sinclair at the Hearings. 19.76 Mbps with a mobile
> antenna while 8-VSB was only up to 19.34 Mbps in a
> fixed position with a directional antenna.

First of all, more recent comparison tests do not paint
this picture across the board, and even these more
recent tests are a couple of years old or more. You
keep harking back to 1999, which of course is pointless.

I refer you back to the CRC comparison tests documented
in the September 2003 issue of IEEE Transactions on
Broadcasting, and then keep in mind what 8-VSB
receivers have done since then when you read their
results. This was the test where they added in the
effect of on-channel repeaters. But they also did a
comparison before introducing the OCRs.

I also refer you to the numbers documented in FCC
05-199 we saw yesterday, which are pretty hard for
COFDM at 3.3 b/s/Hz (aside from echo tolerance). And
to the numbers recommended in A/74 vs Nordig.

But without getting bogged down in this incessant
debate, the simple fact remains that the significant
effort in 8-VSB is going to maintain a high spectral
efficiency while increasing robustness. That's the real
push, not E8VSB. Instead, in France and the UK, they
are doing whatever it takes to get up to somewhere
close to 3.3 b/s/Hz, in order to support HD. Their
main handicap is the low power they want to transmit.

So the inflexibility of 8-VSB is not an issue. Because
reducing the bit rate to increase robustness is not
where the world of TV broadcasting seems to be going.

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