[opendtv] Re: Backward Compatibility of Robust DTV Transmissions

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 7 Nov 2006 18:17:25 -0500

Al Limberg wrote:

> The training wheels (i.e. extra parity) help new receivers.
> The information content in the robust transmission is carried
> in standard 8VSB data segments, which legacy receivers can
> usefully receive.
> In the EVSB, ASB, Philips and ETRI proposals the information
> content is coded in such a way that it is not possible for
> legacy receivers to decode it.  This means information content
> has to be transmitted twice if legacy receivers are to receive
> it and new receivers are to receive it with full robustness.
> This is a major waste of code capability.
> The original goal in the Request for Proposals from ATSC was
> to ruggedize HDTV broadcast or multi-cast SDTV.  The various
> proposals seem to focus on replacing HDTV with other services
> that halve or quarter code rate.  Perhaps this is a tacit
> concession to business opinion that HDTV broadcast and
> multi-cast SDTV will disappear from terrestrial transmitter
> service.


I thought all these non-training-wheel proposals were intended only to
set aside a small fraction of the total bandwidth, more in line with
hierarchical modulation, than to try to patch together some suboptimal
and completely unnecessary new modulation scheme, that ends up reducing
spectral efficiency to nothing better than NTSC.

I would be totally opposed to any such notion. When I become FCC
Commissioner, I'll stone to oblivion anyone who enters my office with
any such proposal.

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