Ictv, Inc.

John F Doyle

Stephen C Snell

Ted Elliott Hartson

Timothy Dunn

Mitchell Askenas

An enhanced scrambled video signal, method for making an enhanced scrambled video signal and apparatus for enhanced scrambling of a video signal are all characterized by a pattern added to a video signal. The pattern is formed from a pair of segments, including a black segment and a white segment which forms a high contrast transition therebetween. The transitions vary in horizontal location from one horizontal line to the next. The pattern causes an unauthorized television receiver to mistakenly lock onto the transitions in the pattern, as if the transitions represented horizontal sync signals, thus scrambling the video display. The apparatus for inserting the pattern may be formed by a sync detector, a video amplifier, a multiplexor and a control logic device. The video amplifier sets the video signal to a DC reference level. The sync detector detects the horizontal sync of the video signal which is sent from the video amplifier. The sync location is passed from the sync stripper to the control logic device which sends control pattern insertion signals to the multiplexor. The multiplexor combines the video signal with the black, white, and gray reference signals based on the control information to add the pattern to the video signal.

Enhanced scrambling of slowly changing video signals

A scrambling system for a cable television system in which a group of channel frequencies are reused over a plurality of service areas includes an access controller, an encoder and a plurality of simplified scrambling units. Each service area receives different television signals on the group of channel frequencies. The access controller provides signal authorization information for a given channel frequency to a plurality of receiver/decoders located in the different services areas. The access controller also provides descrambling information corresponding to the signal authorization information to the encoder for the given channel frequency. The encoder produces a conditional access code by placing the descrambling information into a scrambled reference signal. An extracting unit removes the conditional access code from the scrambled reference signal and distributes the conditional access code to each of the simplified scrambling units operating at the given channel frequency. Each simplified scrambling unit scrambles the television signal that is to be delivered to its respective service area and inserts the conditional access code into the scrambled television signal.

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Campbell, CA, United States of America

John F Doyle