Selectivity Requirements to Eliminate Adjacent Channel Interference on Multi-Channel Catv Systems

TV receiver and transmitter characteristics required for the elimination of visible adjacent channel interference effects are discussed. The interference mechanisms involved are explained. Effects caused by the upper adjacent channel signal are different in nature from those of a lower adjacent channel signal. It can be shown that the suppression of upper channel interference needs little extra effort, if any, in the receiver, but calls for special care in designing the VSB filter response at the transmitter (or headend modulator). To eliminate interference from the lower adjacent channel, however, the receiver selectivity has to meet requirements which are more stringent than those for the upper adjacent channel.