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| Digital TV |
The analog method that
has been used up to this point, refers to transmitting
the brightness of light and loudness of sound as
they are by expressing as electric voltage.
Digital TV, on the other hand, means transmitting
via digital transmission method after digitally
processing everything, including video, audio, and
data.
Digital processing refers to conversion of an analog
signal, such as video, audio, and data, into a digital
signal composed of 0 and 1.This is accomplishedthrough
the use of highly advanced digital technology. A
converted signal is compressed, along with other
information, and transmitted via thedigital transmission
method. The transmitted signal is separated
into the original video and audio, and then< decompressed
(demultiplexing & decoding) at the receiver.
In other words, all information is converted into
numbers and then sent and received. As long as a
1 is sent and can be recognized as a 1 from the
receiving end, there will not be any problem in
converting the signal back to its original state,
regardless of whether there was static or signal
deformation in transit.
It also means the information can be restored just
as it was sent; clear picture and sound of broadcasting
stations can be restored as is.
Therefore, in digital broadcasting, topics, such
as how data can be efficiently and effectively expressed
and compressed as numbers, how a large volume of
data can be sent in one shot, and how errors, if
they occur, can be corrected, are the main interests.
In any event, since digital broadcasting allows
transmission and reception of far more data in their
original state than the existing method, digital
broadcasting is able to provide better picture and
sound qualities. The features can be seen as the
characteristics of Digital TV that guarantee studio-quality
pictures and CD-quality resolution. |
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Analog TV |
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SDTV |
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HDTV |
Scan
Lines |
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525 |
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480x704 |
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1080x1920 |
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480x640 |
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720x1280 |
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Screen ratio |
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4:3 |
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4:3 / 16:9 |
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16:9 |
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Picture Quality |
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Normal |
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Good |
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Very Good |
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Sound |
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2channel, stereo |
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5.1channel/
surround |
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Digital can be classified asHDTV
(high definition TV) and SDTV (standard definition
TV). HDTV is a high-resolution TV method supporting
a 16:9 screen ratio and Dolby digital surround audio.
It has 1080 scan lines (interlaced scan) and is
capable of receiving 18 types of digital broadcasting.
Thus, this method can be said to be capable of clear
picture, marginal picture flickering, and abundant
expression of color tones.
SDTV is a digital TV method with relatively lower
resolution, with 480 scan lines. A screen ratio
is not specified. But since SDTV is also a digital
method, it supports sharp picture quality and uses
less frequency bandwidth than HDTV. SDTV is a good
method for simultaneously supporting interactive
services, such as data broadcasting, simultaneous
broadcasting, and VOD (Video-On-Demand).
Digital broadcasting based on digital technologies
has advantages over analog TV, such as strength
against static and efficient information transmission.
One advantage that digital TV has over analog TV
is the capability to provide high-quality service.
While the vertical resolution of analog TV is at
a mere 330i. The HD (high definition)-grade digital
TV reaches 720p, which provides pictures that are
approximately four times as clear than analog TVs.
Moreover, if PDPs or LCDs are adapted to receive
digital data broadcasting instead of the existing
CRTs, the high resolution provided by PCs can be
realized.
In terms of sound quality, digital TV provides outstanding
sound that is far superior to the quality of a CD's
sound. While the existing analog TV merely provide
two-channel stereo sound, digital TV, which uses
Dolby digital sound technology, provides the three-dimensional
sound of 5.1 channels. In addition, in terms of
screen ratio, analog TVs rely on the horizontal-to-vertical
ratio of 4:3. HD-grade digital TVs boast the ratio
of 16:9, which is identical to screens at movie
theaters. The horizontal-to-vertical screen ratio
of 16:9 is the screen ratio that allows people to
"visually feel" like they are really there
on scene.
The advantage considered to be the most innovative
of digital TV is their functionality as a two-way
multimedia terminal. Since all information is processed
digitally, not only Internet access (web browsing)
via TV but also data search while viewing programs
(multi-windowing),< will be possible.When the digital
TV is connected to the outside, a wide range of
two-way value-added services can be provided through
them. As the TV that used to be a one-way visual
entertainment device transforms into a cutting-edge
informational device with two-way multimedia functionality,
the status that TV assume within people's home is
expected to change as well. Digital TVs are data-compatible
with devices that process signals digitally, including
digital multi-function DVD players, digital camcorders,
and digital VCRs. Therefore, digital TV is being
touted to work as the nerve center of a home, which
all digital devices at home are connected as one
network. |
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