TV bandwidth compression techniques using time companded differentials and their applications to satellite transmissions

Various methods to compress the bandwidth of an NTSC color TV signal are described. The methods are based on taking differences between adjacent or successive scan lines and then performing time companding on these differential signals. In the three specific methods outlined, a 4.2 MHz TV signal can be bandwidth reduced to 3.34 MHz, 2.9 MHz and 2.5 MHz, respectively without loss of picture quality. When these techniques are used with time compression multiplexing in satellite transmissions, high spectral efficiency can be obtained. Examples are shown where two or three broadcast-quality TV's per 36 MHz transponder is possible with existing technology.