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Simple and stupid question..

Last response: in Home Theatre
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August 29, 2004 12:10:22 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

How does HDTV work?

I would think HDTV would have so much information that you'd need
digital to get it...thus digital cable. So how would satellite cable
work with it?

Up until now, I have a regular (1980s) TV. It just broke. If I want
to buy a regular TV (non-HDTV) will that mean that it won't work when
all the stations switch to high definition broadcasts? Or will their
regular analog broadcasts be the same?

If HDTV is over analog (I think I heard it was), I don't understand
how they do it without taking alot more of the spectrum. The spectrum
is expensive, so I am a little confused on this.

I think I read that you can buy a converter of some kind eventually.
If I buy a regular $100 TV now, will I be able to buy a converter to
get HDTV on my $100 TV? Or will it just give regular TV (non HD) over
my $100 TV?

If I buy a HDTV now (not likely as they are expensive), I guess
there's no real point as almost everything is non-HDTV broadcast.

What is the cutoff date for them to switch over?

Any recommendations?

Sorry for all the simple questions.

Will cable HD (when they have it) over a $100 TV not really work? I
would think it wouldn't.

More about : simple stupid question

Anonymous
August 29, 2004 4:28:47 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

"brianb" <bri1600bv@hotmail.com> wrote in message
news:68a6629.0408281910.448b60e4@posting.google.com...
> How does HDTV work?

HDTV is digital... the picture is encoded in MPEG-2 - same as DVD's except
much more resolution for HD and uses dolby digital 5.1 surround sound

HD pictures are typically 24 bits deep (32 million colors) and 1920x1080
pixels (1080i) or 1280x720 (720P), HD can carry standard definition as well
which is 720x480(SD). SD quality is the same as really good DVD.
Conventional analog TV is exceptional if it gets a 400x400 image up on the
screen and in reality, the color of analog TV is more like 100-200 pixels -
cartoon color.

Over the air, it uses a system called ATSC to describe the 19.5 million bits
per second in packet stream and how they are modulated onto the RF signal.
OTA HDTV takes up no more bandwidth than conventional analog TV because of
how it is modulated and compressed.

ATSC allows for multiple channels of programming to be streamed in one
channel. So my local NBC-DT has 3 sub-channels. 12-1 is the HD channel in
16:9 aspect ratio, 12-2 is the standard def version in 4:3, 12-3 is the
local radar feed.

Cable systems use a different modulation scheme than OTA and typically
recodes the packet streams to eliminate all bits except for the ones for for
the main -1 channel. So the same NBC channel that has 3 subchannels OTA,
only has one channel, 12-1, on cable.

A single cable or satellite HD channel takes up the same bandwidth as 6
so-called "digital quality" channels on digital cable or sat, so don't
expect cable/sat to carry everything HD. Typically, an HD cable has maybe
9-10 HD channels, half of them premium pay channels like HBO, Showtime,
Starz and CineMax.

ESPN-HD, Discovery HD, the major networks ABC,CBS,NBC and a couple of
eye-candy channels (INHD or HDNet) are all you can expect "free" on HD cable
for a while.

To watch HD from broadcast, you need either an over the air HD tuner box and
an HD monitor (which has either high bandwidth component analog or DVI
inputs) and an HDTV with an integrated HD tuner.

The cable guys will rent you an HD set top box to convert the cable HD into
something the HD monitor or HDTV can show. Ditto for satellite except you
own the box.

Hope this helps.
Anonymous
August 29, 2004 9:11:41 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

"brianb" <bri1600bv@hotmail.com> wrote in message
news:68a6629.0408281910.448b60e4@posting.google.com...
> How does HDTV work?
>
> I would think HDTV would have so much information that you'd need
> digital to get it...thus digital cable. So how would satellite cable
> work with it?
>
HDTV IS digital. It is a compressed MPEG-2 video stream and a compressed
AC3 (i.e., Dolby Digital) audio stream. This is very similar to a straming
video file that you watch on the internet. The way the digital content is
sent to you is known as a modulation scheme. The bandwidth on the air,
cable, or satellite is chopped up into ranges of frequencies called
channels. On the air normal TV takes up one of these channels to send an
uncompressed analog NTSC picture. OTA HDTV also takes up a portion or all
of one of these channels, but uses it to send a compressed bitstream that
encodes a broadcast of a higher resolution. The three receptions use
different and mutually incompatible modulation schemes called 8-VSB, QAM,
and QPSK recepectively, so a receiver that works with one scheme will not
work with the other. That's to get some or all of these receptions you will
need a set top box or a cable card depending on which type of receiver, if
any is built in into your TV.

> Up until now, I have a regular (1980s) TV. It just broke. If I want
> to buy a regular TV (non-HDTV) will that mean that it won't work when
> all the stations switch to high definition broadcasts? Or will their
> regular analog broadcasts be the same?
>

FCC leases the on-air spectrum to broadcasters. Based on current government
regulations, at some time in the future NTSC broadcasts off the air are
mandated to be ceased. At that time an NTSC only TV will not work with an
antenna. Cable companies are not required to end NTSC transmissions since
their bandwidth is not leased from the FCC. You could keep getting
broadcast through them. Whether it'll be the same of different is not
known. If I was to guess it'll be different. This is because the
broadcasts are only supposed to cease when 85% of the households have HDTV
penetration. If this actually means they have HDTV's the cable companies
will likely not bother down converting broadcast signals, and taking up the
bandwidth with them. Instead the down conversion will likely be done with a
set top box.

> If HDTV is over analog (I think I heard it was), I don't understand
> how they do it without taking alot more of the spectrum. The spectrum
> is expensive, so I am a little confused on this.

It does add to the spectrum. It takes up other channels that are not in
use. The theory is that once the NTSC broadcasts cease FCC will get that
portion of the spectrum back, and will be able to lease it out again.

>
> I think I read that you can buy a converter of some kind eventually.
> If I buy a regular $100 TV now, will I be able to buy a converter to
> get HDTV on my $100 TV? Or will it just give regular TV (non HD) over
> my $100 TV?
>

The second part of HDTV equation is the TV set. A true HDV quality
broadcast is either 720p or 1080i. What that means is that the broadcast
has 720 or 1080 lines of data and is broadcast progressively in the first
case and interlaced in the second case. An NTSC broadcast is 480i. If a
$100 TV was to get the 180i or 720p signal it will not be capable of
displaying it, because it is limited to 480i. A TV set capable of
displaying a 720p and 1080i signal is HDTV ready. If it has a receiver
built in, it IS HDTV. When that downconverter is available, it will take
the HDTV broadcast and covert it down to a 480i signal for the cheap TV.
The picture quality will be equal to DVD quality. True HDTV is far
superior.

> If I buy a HDTV now (not likely as they are expensive), I guess
> there's no real point as almost everything is non-HDTV broadcast.
>

There already is a lot of free HDTV broadcast on the air and the cable
companies also send most of it unencrypted. The reason you do not see it
right now because to a non HDTV, those channels have nothing on them. Most
of the prime time shows are already broadcast in spectacular widescreen
HDTV. The exception to this are those reality TV shows.

> What is the cutoff date for them to switch over?

The cutoff date for ceasing NTSC broadcast was set at 31 December 2006 IIRC.
Whether it is actually going to happen that soon is not known at this time.
IMHO it'll be pushed out further as 85% of the households do not own HDTV.
If the interpretation is that 85% can potentially get HDTV, then the cutoff
can happen on that date.

>
> Any recommendations?
>

I'd recommend visiting the store and taking look at the CRT (i.e. tube
screen), HDTV sets if you are on a tight budget. These sets are around $500
and coming down fast. If you are impressed enough with the picture quality
for that price, go for it. If you think the PQ is not as good as the more
expensive or the larger sets, and you'd rather wait for those to come down
(and they will)., then get the cheap TV.

> Sorry for all the simple questions.
>
> Will cable HD (when they have it) over a $100 TV not really work? I
> would think it wouldn't.

With not work, if you mean a completely blank picture. Then no, this is
likely never going to happen during the service life of any TV you buy
today. If this were the case, these TV's will be off the market as we
speak. When everything is HD your set top box will give you a picture
better than you get now, it just won't be as good as your neighbor who has a
real HDTV. And your questions are far from simple, and definitely not
stupid.
Anonymous
August 30, 2004 1:27:07 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

On Sun, 28 Aug 2004, brianb wrote:
> How does HDTV work?
>
> I would think HDTV would have so much information that you'd need
> digital to get it...thus digital cable. So how would satellite cable
> work with it?

Since others have answered the other questions, I choose to answer only this
one:

I have noted the emergence of satellite receivers that have RGB/yPrPb outputs
for HD sets. I have one of those for my large set. My small bedroom set (30")
inherited my older, NTSC-output MPEG2-DVB box, and it can display the same
signals pretty well, but because of its NTSC output, any HD signal gets
480i'ed, so I lose the additional quality but otherwise get a perfectly fine
picture.

I have seen DirecTV, Dish, and MPEG2-DVB HD satellite receivers. I did not
look for nor encounter a 4DTV HD receiver as I did my search. [That takes care
of all four digital satellite formats legally available in the U.S.]

> Up until now, I have a regular (1980s) TV. It just broke. If I want
> to buy a regular TV (non-HDTV) will that mean that it won't work when
> all the stations switch to high definition broadcasts? Or will their
> regular analog broadcasts be the same?

It, as a standalone unit, won't work at all when the TV stations cease their
analog broadcasts as there will be nothing to receive. With either a DTV
add-on converter box, a cable box, or a satellite box (or just your VCR and/or
DVD), it will still be a functional TV.

> If HDTV is over analog (I think I heard it was), I don't understand
> how they do it without taking alot more of the spectrum. The spectrum
> is expensive, so I am a little confused on this.

It's over the same channels, but you need to know how the signals are formatted
to understand the difference. Analog signals don't really use the entire
bandwidth (and certainly not evenly); digital signals do.

> I think I read that you can buy a converter of some kind eventually.
> If I buy a regular $100 TV now, will I be able to buy a converter to
> get HDTV on my $100 TV? Or will it just give regular TV (non HD) over
> my $100 TV?
>
> If I buy a HDTV now (not likely as they are expensive), I guess
> there's no real point as almost everything is non-HDTV broadcast.
>
> What is the cutoff date for them to switch over?

Originally scheduled: 12/31/2006 is the cease of operations date for analog
TV, with an alternative: 85% market saturation of DTV capable households -
which MAY (we're not certain) include cable and satellite TV capable as the
cable and satellite providers may handle format conversions. This is on a
per-TV-market basis of which there are a little over 200 areas in the U.S.
Whether or not this is on schedule or will be delayed may be under
consideration by the government. [I know I may have oversimplified this.]

> Any recommendations?
>
> Sorry for all the simple questions.
>
> Will cable HD (when they have it) over a $100 TV not really work? I
> would think it wouldn't.

The cable box converts it to NTSC in that case, so you will see a picture, but
obviously not an HD one.
!