Benefits of DTV and HDTV
There are many benefits to having Digital TV and High Definition
Television. Overall there are numerous reasons to make the switch:
Digital superiority, amazing detail, progressive scanning, digital audio, no more 'ghost'
images, the FCC mandating a switch, a wider viewing area,
better quality DVD playback and so on. We have listed
the major reasons in detail below.
The New Aspect Ratio
Current televisions are based upon the aspect ratio of 4:3. This means a TV
with an aspect ratio of 4:3 will be 3 feet high and 4 feet wide.
With HDTV the aspect ratio is 16:9,
making the image much wider than a normal TV. The new screen size is 33% wider to be exact.
The increased width is a huge improvement because it allows you to view TV and movies
as if you were watching them in a theater. When watching TV on a 16:9 screen you use
your peripheral vision, which truly makes you feel like you are a part of the program.
Norm Samat, the directory of ABC's Monday Night Football HDTV feed put it perfectly:
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| You almost get into a trance looking at HDTV pictures because you
really see more. The wider 16:9 aspect ratio makes a big difference in covering football. With
the old 4:3 aspect ratio screens it was often tricky to cover the defense. In HDTV they are
already in your picture, so you can see more of the play develop. |
Resolution
The usual resolution a normal NTSC TV can display is 525 scan lines with 480 actually being
visible. The usual TV can display a resolution
of about 210,000 pixels per image. High Definition TV's can go all the way
up to 1920 (horizontal) x 1080 (vertical)
pixels, with a total of 2,073,600 pixels per image. That is ten times the resolution and
picture quality. Ten times!
In fact, when you squeeze all these pixels down to the same sized TV you get impeccable
quality. Instead of stretching these pixels out, they are crammed together so tight
that resolutions get as high and as sharp as they do.
Sound Quality
High Definition television also has 5.1 channels of CD-quality surround
sound (left, right, center, left rear, right rear, and low frequency effects - AKA bass).
These multiple channels bring you true surround sound at an amazing quality.
With the older NTSC standard you only get two channels of audio, which is just
enough to make it stereo. With HDTV you are listening to Dolby Digital/AC-3 which is the
same that is used in most movie theaters, DVD players and home entertainment systems!
No More Ghost Images
Many times signal quality is not perfect when watching regular NTSC television, which gives
you what are called 'ghost images'. A ghost image is when you see two of the same person
next to each other, as if there is a ghost of that person next to himself.
With a digital signal you will always get a perfect image as long as the TV is receiving
a quality signal. This means no more fuzz, no more snow and no more ghosts. Television the way
it was meant to be watched!
Progressive Scanning
Regular NTSC signals are shown as interlaced signals. This means every other horizontal line of
the monitor is displayed in one frame, and the other half of the horizontal lines are drawn in the
next frame of the picture. This works because it happens so fast that the eye is deceived into
believing that only one picture is being shown. Below this is shown in slower motion and on an
image that is not moving for explanation purposes.
Progressive scanning, on the other hand, displays the entire picture in one frame. This provides
a sharper picture to the eye and looks much better than an interlaced image of the same resolution.
With DTV there are two progressive formats for broadcasters to choose from: 480p and 720p. A 480p
image is without question much sharper than a regular, NTSC broadcast, although it is only
considered a DTV signal and not a true High Definition signal. 720p has 720 horizontal
scan lines and is considered to be true HDTV. 720p can many times rival a 1080i picture,
which is 1080 horizontal scan lines
displayed as an interlaced image. This is because of the sharper, and more accurate picture 720p displays,
even though 1080i has many more scan lines and a much higher resolution.
Multicasting
Multicasting is when a broadcaster sends multiple signals out over the same channel. Usually
when multicasting, the quality of the broadcast is less than that of HDTV, but it is almost
always better than regular NTSC television.
The benefit of multicasting is that a television station can air four or more signals at the same time
and give you the choice of what you want to watch. There have been reports of stations multicasting
a HDTV signal and an EDTV signal without much loss in the High Definition Signal, however this is usually
not the case.
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