Broadcast Engineer's Reference Book
Providing detailed coverage and quick access to key technologies, standards and practices, this authoritative reference work covers the broad landscape of television technology in one handy source.
TABLE OF CONTENTS Broadcast Engineer's Reference Book
Chapter 2.3: Television Standards and Broadcasting Spectrum
R S Roberts C Eng, FIEE
Sen MIEEE Consultant Electronics Engineer
Revised by
Chris Dale MIIE
Previously BBC Broadcast Networks Engineer
Television systems can be divided into two groups for the purpose of describing how they function: analogue TV systems have been with us for over 70 years, and all depend on being able to transmit a continuously varying signal level over a distance, representing the picture information. Several digital TV systems have been developed in the last 20 years. All transmit the picture information by changing the continuously varying signal levels from the camera, or other source equipment, into a series of codes consisting of two or more discrete signal states. Some digital systems are suitable for local distribution in studios, and others, described here, are suitable for broadcast transmission.
2.3.1 Analogue Television Systems
Every analogue colour television channel consists of three modulated carriers:
-
The vision information, derived from a camera or other signal source, is used to amplitude modulate a carrier with the electrical equivalents of the basic 'black and white' variations that are encountered during transmission of the scene.
-
A subcarrier, situated within the bandwidth of the vision modulated carrier, is itself modulated with information related to the colour information in the scene.
-
A separate adjacent carrier is modulated with the sound information contained in the scene.
The eye, as a visual communication system, 'sees' a large amount of detail simultaneously, by virtue of the fact that it has several million communication channels operating...
Copyright Elsevier Inc. 2004 under license agreement with Books24x7
