الموجة الحاملة والأقنية التلفزيونية ٢-a .. كتاب التلفزيون الملون والعادي

Acoustic signals:

The audio signal is transmitted on a carrier wave that is 5.5 MHz higher than the image carrier wave) and it is FM frequency modulated in the European system and AM amplitude modulated in other systems.

We have seen that the side bandwidth of the image extends to (5) megahertz, while the width of the audio bandwidth is about (200) kilohertz (KHz). Figure (1) - (20) shows the transmission curve of the image and sound in the European television system. ) megahertz in the European system, while it is (6) megahertz) or (5) megahertz) or otherwise in other systems. As we will notice in the comparison between these systems in the table shown in Figure (1-21).
Audio and video transmission curve

European system

The channel width is 7

MHz and the image bandwidth is 5 MHz

The audio bandwidth is 200 kHz

The difference between the video and sound carrier is 5.5 MHz
1-7 Basic circuits common to black and white television and color television

The functioning of a television set is similar to that of a radio in that it receives through an antenna - radio signals, which are radio waves that carry sound or image information. After selecting and tuning the desired station, its signal passes through radio amplifiers (IF). It is then mixed with the frequency of the local oscillator. This method is called (super heterodyne) or (interstitial conflict). It results in the intermediate frequency (IF), which is amplified through several stages until it reaches the image and sound detector, and extracts the information that was sent from the station. Figure (1-22) shows the black and white TV box diagram.

As for the color television set, it requires additional information that accompanies the image-carrying signal, which is, as we have previously explained, the synchronization, switch-off and equalization pulses. . In the color device, new stages must be added to extract the colors and their appearance on its screen, which is different from the monochrome screen, and the sensitivity, tuning, and tuning of the circuits must be tighter and more accurate.