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Re: HDTV WHY???



In a message dated 97-10-02 18:34:35 EDT, Rob wrote:

<< so it was an FCC mandate that enabled the advance in technology for radio,
and so it should have been with HDTV... were there really no strings attached
to the FCC's recent gift to the networks of extra bandwidth?  Did the US
government not suspect that it might not be used for HDTV? >>

Actually, all the technological advances in FM radio had already been made;
it was the FCC's mandates on original programming and FM stereo that made FM
attractive enough for listeners and broadcasters to turn the system around.
 The key to its revival was turning FM into a very diffferent service than
AM.  Likewise, I think DTV is going to languish as long as you can still turn
on any old analog television and see precisely the same stuff.  Just because
the DTV picture and sound are better is not reason enough to buy one if
there's nothing new to look at!

As for the "gift of bandwidth" represented by broadcasting channels, a lot
could be said about the free ride commercial broadcasting has had since the
very beginning on public airwaves.  Nothing's changed in DTV, and the
broadcasting lobby worked very hard to keep it that way.  Aside from that,
the broadcasters were pretty successful in keeping the FCC out of programming
choices or even deciding how the bandwidth of a DTV channel can be utilized.

A big part of the problem was the way the current TV channel assignments were
made, in 1948.  At that time, little was known about VHF propagation.  It was
thought that beyond the horizon, radio waves just disappear off into space.
 So the TV channels were arranged with only marginal space between them, the
theory being that you'd only be able to tune in your own service area anyway.

Well, guess what.  As most ham radio operators know today (and many knew back
then as well), VHF propagation can be rather whimsical in nature.  Some days
a given frequency won't go 50 miles, other days it will put you in touch with
somebody 500 or more miles away.  Where the same television channels were
assigned in adjacent service areas, lots of occasional, severe interference
problems resulted.  The only way to eliminate this was to stagger the channel
assignments.  So present-day VHF television works, but fully half of its
spectrum is wasted!

The real purpose of DTV, then, is to take advantage of digital techniques to
consolidate VHF and UHF broadcasters into a smaller block of spectrum so the
rest can be recovered and sold.  The broadcasters just made sure they were
liberally compensated for playing along with the game!

Cordially yours,
Christopher Bacon

---
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