Gigahertz and Terahertz: Technologies for Broadband Communications
Concise 30,000 foot view of wireless and fiber-optic broadband
communications technologies.
TABLE OF CONTENTS Gigahertz and Terahertz: Technologies for Broadband Communications
Chapter 5: Digital Television
5.1 Convergence revisited
Today almost everyone agrees that digitization is the way to go as far as signal transmission and processing are concerned.
While all real-life signals are initially strictly analog, the digital encoding of these signals at the earliest possible point well ahead of transmission provides immense benefits. This concept makes sense for several compelling reasons, for example:
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Minimization of noise effects;
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Enabling of substantial bit-compression of video and audio signals;
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Enabling error correction to be deployed (which is not feasible with analog);
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Digitization means that identical processing techniques can be used for all signals, whether audio, control, data, or video;
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Encryption is easily arranged;
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Channels can be easily allocated;
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Lower (than analog) transmission power is usually required;
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Robust modulation schemes, combating ghosts and phase problems, may be implemented;
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The implementation of truly high definition displays (HDTV) makes much more sense than with analog;
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Compatibility with most of the burgeoning digital technology that is generally available (e.g., VLSI technology);
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Compatibility with many of the increasingly digital transmission systems that are being implemented in almost all G8 countries for at least cable and satellite.
By the late 1990s these advantages were realized with the introduction of digital television (DTV) in several countries. DTV was initially pioneered with satellite (DTH) but has since become possible using terrestrial broadcast TV mainly as a result of the advances in digital compression technology.
There are, however, some drawbacks to implementing digital TV and the main ones are:
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The quality of service degrades rapidly...
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