Television signal processing system

Claim 1

A television processing system in a wireless pay-television system wherein a television signal is encoded by an encoder, the coded signal is transmitted to subscribers' ends, and the coded signal received at each of the subscribers' ends is decoded into an ordinary television signal by a decoder, which system is characterized in that said encoder processes and encodes the television signal by inverting a synchronizing signal component thereof with reference to a pedestal level and expanding said component to an extent not exceeding a peak value of a video signal component and by reducing the number of horizontal synchronizing signal components so that each of the horizontal synchronizing signal components may correspond to plural lines; said decoder including: a horizontal synchronizing signal extracting circuit adapted to be driven by the coded television signal for generating a signal having the same period as a horizontal synchronizing signal; a vertical synchronizing signal extracting circuit adapted to be driven by the coded television signal for generating a signal having the same period as a vertical synchronizing signal; a PLL circuit for obtaining a signal having the same frequency and the same phase as the horizontal synchronizing signal component from an output from said horizontal synchronizing signal extracting circuit; a switching signal generating circuit adapted to be driven by an output from said PLL circuit and the output from said vertical synchronizing signal extracting circuit for producing a switching signal; a synchronous reproducing circuit adapted to be driven by the output from said vertical synchronizing signal extracting circuit and the output from said PLL circuit; and a television signal switching circuit adapted to be driven by the switching signal for selectively outputting the coded television signal or an output from said synchronous reproducing circuit.