Abstract: An decryption system which facilitates simultaneous decryption of multiple encrypted television channel signals thus making them simultaneously available for direct tuning in television receivers. The system is characterized by the utilization of a plurality of channel signals time synchronized with respect to a common timing reference signal. Each channel signal is encrypted in accordance with a predetermined encoding rule and distributed to subscriber sites where an unencrypted block of channel signals are made simultaneously available by decrypting them synchronously with the recovered timing reference signal in accordance with the inverse of the encoding rule. An interdiction apparatus then selectively jams a plurality of television channels from within the unencrypted block of channel signals thus making it possible for a provider to programmably interdict reception of selective channels by unauthorized subscribers.

Abstract: An encryption/decryption system which facilitates simultaneous decryption of multiple encrypted television signals thus making them simultaneously available for direct tuning in television receivers. The system is characterized by the utilization of a plurality of channel signals each containing picture portions and synchronization portions respectively corresponding to the picture components and synchronization components of a different video signal. Corresponding portions of all channel signals are time synchronized with respect to a common timing reference signal. Each channel signal is encrypted in accordance with a predetermined encoding rule and distributed to subscriber sites where the channel signals are made simultaneously available for viewing by decrypting them synchronously with the recovered timing reference signal in accordance with the inverse of the encoding rule.