Encoding and decoding of a television signal.

摘要

A video signal is encoded in a pattern which changes from field to field. The encoding pattern starts at the Nth line where N is a random number generated afresh for each field, and thereafter alternate lines have their video portions noninverted and inverted. Further encoding may be achieved by shifting the horizontal synchronisation pulses of certain lines starting from the Nth line and this shifting is applied to bands of lines separated by bands of lines in which the synchronisation pulse is left unchanged, in a regular pattern. In a transmission system, the encoded video signal is combined with the encoding data and an audio signal for modulation of an rf carrier. The decoding information may be applied to a sub-carrier.