TABLE OF CONTENTS The first problem facing the transmission of colour TV signals is compatibility with the existing monochrome transmission. When colour television was first introduced, it was agreed that colour TV signals must be capable of producing a normal black and white image on a monochrome receiver without any modification to the television set. Conversely, a colour receiver must be capable of producing a black and white image from a monochrome signal. A colour transmission system must therefore retain the monochrome information, sync pulses and the sound inter-carrier in the same form as those of normal monochrome transmission. The additional colour information has to be included within the composite video signal without interfering with it. Furthermore, the colour signal must fall within the same bandwidth as that allocated for monochrome transmission. To understand how this may be done, we must first look at the properties of light and colour.
We know radio and TV broadcasts are electromagnetic waves of various frequencies and various broadcast bands have already been mentioned in Chapter 1. As we go up in frequency we pass through the bands allotted to radio transmissions, followed by terrestrial TV broadcast and space communications. Way beyond these we come into an area where electromagnetic radiation is manifest as heat, and continuing upwards we find infra-red radiation, and then a narrow band (between approximately 4 10 8 and 8 10 8 MHz) of light energy. Beyond the light band we pass into a region of ultra-violet radiation,...
