HDTV, an abbreviated term for High Definition Television, is a television broadcasting system with higher resolution than traditional television systems such as Analog and Digital Television (DTV). Majority of the High Definition Televisions offer over 1,000 scan lines, in a wider aspect ratio (16:9) and with superior color & sound fidelity. HDTV systems also have additional features such as sound systems based on Dolby Digital technology with 5.1 channels.
Differences in Analog TV, Digital TV and High Definition TV
Few years back, watching television on Analog TV involved the use of cathode ray tube or CRT sets and analog signals. The analog signal consists of continually varying radio waves, which are translated by the TV into sound and picture. Analog signals are transmitted via satellites or through cables. The limitation associated with Analog TV is that the traditional CRT televisions display about 480 visible pixel lines. Analog pictures are interlaced, and Cathode ray tube’s electron gun does not have the capability of displaying the entire picture. Whereas, a Digital Television or DTV system is much different from analog TV system, as it transmits the information in the form of ones and zeroes instead of a wave, to give the output as sounds and moving images. For over-the-air broadcasting, a Digital Television generally uses the UHF part of the radio spectrum, having a bandwidth of 6 MHz.
A DTV system has some advantages over an Analog TV system, which are as follows:
- A DTV signal allows the broadcasters to include additional information or interactive content for their viewers.
- A DTV signal allows TV stations to transmit many signals using the same bandwidth.
- With a digital signal, the TV screen displays the entire picture for all frames.
However, even a DTV has a major limitation. DTV images are not perfect and have some defects. This is considered a major limitation because these defects are seen in analog televisions. And this is where HDTV appears. HDTV is more advanced than an analog television or DTV.
The ATSC (Advanced Television Systems Committee) has formulated 18 most commonly used digital broadcast formats for video. And the lowest quality digital format of an HDTV is approximately similar to the highest quality digital format that an analog TV can display. These 18 formats differ in terms of aspect ratio, resolution and frame rate of television sets.
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