Patent ID: 6873371

Claim:
A communication system for transmitting and receiving video signals divided into a plurality of successive fields, each said field consisting of a prescribed number of lines of information, said lines being of uniform respective duration, said system comprising: transmission apparatus including a reference signal generator for transmitting during a prescribed single line of each of said fields a first ghost-cancellation reference signal and a second ghost-cancellation reference signal different from said first ghost-cancellation reference signal, each of said ghost-cancellation reference signals being transmitted with a modulation swing less than the maximum modulation swing available but more than half said maximum modulation swing, the relative phases of said first and said second ghost-cancellation reference signals varying from field to field in a prescribed pattern to facilitate their separation by a television receiver, said first ghost-cancellation reference signal having a prescribed first duration longer than half a line duration, and said second ghost-cancellation reference signal having a prescribed second duration shorter than half a line duration; and reception apparatus equipped with adaptive ghost suppression filtering, said ghost suppression filtering further comprising means for separating the first and second ghost-canellation reference signals from one another and from received video signals; a ghost cancellation filter provided with adjustable filtering weights; an equalization filter provided with adjustable filtering weights and connected in cascade with said ghost cancellation filter to respond to the received video signals; means responding to the separated first ghost-cancellation reference signals to calculate a discrete Fourier transform therefrom; means responding so said discrete Fourier transform to determine the adjustable filtering weights of said ghost cancellation filter for enabling said ghost cancellation filter to cancel ghost components of said received video signals resulting from said channel transmission delay distortion; and means responding to the separated second ghost-cancellation reference signals to determine the adjustable filtering weights of said equalization filter for enabling said equalization filter to provide a flat spectrum over the entire frequency range for said ghost cancellation reference signals transmission.