Re: Is all current television equipment becoming worthless?


>We dont have that now....
>I dont know if they use the same transmitter for both the analog
>signal and the hdtv, or if they are broadcasting both separately, but
>right now both exist and I dont see why tv stations would change to
>anything else.

No, the systems are completely different. Digital TV requires brand
new high power transmitters, new processing equipment, a new antenna,
new microwave or fiber links. In many cases, the broadcaster is faced
with a fully-loaded tower for the old system and must construct a new
one. Add an upgraded 100 KW emergency generator because both systems
are "on" at the same time. The cost of this can be millions of
dollars for "each" station. Don't even mention the electric bill.

When this was first proposed, the broadcasters howled. No one wanted
to invest millions of dollars in a system that could not be watched
(no member of the public had a digital tv) and would not directly add
to revenue.

Now it is a competition between broadcasters, cable guys, and
satellite providers as to who can offer the best picture. The
broadcasters are smart and realize the benefits of an upgraded
technology. When the switchover occurs in 2009, for many viewers it
will be seemless, as they will already be watching on a digital TV.

>Why cant they "encode" a analog signal right in with
>the hdtv signal? Has anyone looked into that? Rather than the govt.
>forcing everyone to buy converters, and spending tax money t do it,
>why not just make the tv stations re-do their transmitters to handle
>both signals combined. I'm sure it would cost the govt. less to
>assist them than make every tv owner buy converters. I'm sure the
>technology exists or could be developed.
>
>Its like someone else said about the change from B&W tv to color.
>They made them backward compatible. This should occur now.
>

Yes, it would be great if you could change the laws of physics....
Maybe those Maxwell equations don't really exist.... :>

Seriously, though...

The history of NTSC TV consists of cramming the maximum amount of
analog information in a limited 6 Mhz bandwidth. They cut most of
the video carrier to a vestige of it's former self (Hence, vestigial
sideband). The engineers searched long and hard for a spot to add the
aural (audio) carrier so as not to interfere with the video.

Then they wanted to add color and make it backwards compatible. Most
said it "couldn't be done" but some of the best minds said that if you
set a phase modulated signal at 3.58 Mhz and put it in there with the
video, it just might work. They crammed the chroma signal in there
and it did work. They added a color "burst" signal to keep it in
synch.

In the 1980's, they wanted to add stereo audio and something called
VITS and VIR Test signals, so those were added. Data signals from
who-knows-where fill up the vertical interval.

The end result is that the NTSC bandwidth is truly maxed out and there
is simply no place to add a high definition digital signal and keep it
compatible with existing TV.

Digital signal processing and compression is, on the other hand, of
tremendous value to broadcasters.

Back in the early 90's, a typical satellite had 24 video transponders
with a capability of one 6 Mhz video signal for each transponder.

In one day, , they put digitally compressed signals on each of these
transponders and gained 4 or 5 fully compatible video signal channels
for each transponder. This "Quadrupled" the satellite capacity
overnight. Do you think you have too many home shopping channels on
your cable TV?

The government realizes that for some people, it is going to be a
bitter pill to make this changeover. Otherwise, they would not be
speaking of subsidies.

The benefit of this pain will be a much better system for all,
however... IMO.

Beachcomber


.

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