Newsgroups: sci.electronics
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From: dlleigh@media-lab.media.mit.edu (Darren Leigh)
Subject: Re: HDTV: feasible?
Message-ID: <1991May30.154742.23314@news.media.mit.edu>
Sender: news@news.media.mit.edu (USENET News System)
Organization: MIT Media Laboratory
References: <1991May24.223204.2166@murdoch.acc.Virginia.EDU>
Distribution: usa
Date: Thu, 30 May 1991 15:47:42 GMT

In article <1991May24.223204.2166@murdoch.acc.Virginia.EDU> cfk6u@fermi.clas.Virginia.EDU (Charles F. Kramer) writes:
>
>	Zenith currently has a proposal in with the FCC to broadcast
>digital High Definition TV signals _between_ normal TV ones, at low
>power, to minimize interference.  DOes this sound feasible, practically
>speaking?

I think the above is essentially correct, but it is phrased poorly.  I
understand that the current philosophy is to use the taboo UHF channels
for HDTV broadcast and use somewhat lower power than the current scheme.

Because NTSC has all those nasty, strong carriers, it is possible to get
adjacent channel interference.  Therefore, the FCC doesn't assign
adjacent channels in the same area.  HDTV signals will have a pretty
flat spectrum (due to more efficient use of the bandwidth) and will have
methods for dealing with interference.  Therefore, they can go in the
taboo channels without interfering with or being interfered by the
existing channels.

A lot of the power broadcast by a TV station is in the video carrier.  A
good HDTV system won't have this and so can broadcast more information
with less power.

There's some nice technology going into this stuff and I look forward to
it hitting the market.

Darren Leigh
dlleigh@media-lab.mit.edu
Disclaimer:  I have no connection with the MIT HDTV people.