Television transmission network with scrambling and descrambling

Claim 1

A scrambler for scrambling video and audio information signals to be transmitted as a TV composite signal in a controlled access television communications network, the scrambler comprising: (i) means for stripping synchronization signals from said video information signal; (ii) means controlled by said synchronization signals for digitizing the video information signal; (iii) means for segmenting the digitized video information signal; (iv) means for randomly re-ordering the segments of digitized video information; (v) means for deriving decryption data in correspondence with the random re-ordering of said segments; (vi) means for deriving control signals specifically addressed to respective receiving stations of the network for selectively enabling and disabling the descramblers thereof; (vii) means for deriving a video data stream representing a composite of said re-ordered segments of video information, said synchronization signals, said decryption data and said addressed control signals; (viii) means for digitizing said audio information signals; (ix) menas for segmenting the digitized audio information signals in correspondence with the segmenting of the video information signal; (x) means for randomly re-ordering the segments of audio information in correspondence with the decryption data; (xi) means for deriving an audio data stream representing an audio information signal from the re-ordered audio information segments; and (xii) means for combining said video and audio data streams to produce the TV composite signal; wherein said means for randomly reordering the segments of digitized video information comprises a single memory having a plurality of address locations, single address means for addressing the memory such that each address is valid for both a read operation and a following write operation, means for writing the seqments of video information into the memory with a randomly time-varying non-sequential address, and means for reaing the segments of video information sequentially from the memory and for replacing each segment of video information so read from the memory by a next segment of video information to be written into the memory.

Claim 8

A method for encryption/decryption processing of an input composite video signal which comprises segments of video information within successive time slots in a synchronization framework defined by sychronization information contained by the signal, sid method comprising: separating said segments of video information from said sychronization framework; writing said successive segments into locations in a memory device addressed according to a randomly time-varying sequence; reading said segments from locations in said memory device addressed according to a different sequence, each segment of video information read from an addressed location in the memory being replaced by a next segment to be written into the memory; and reintegrating said segments into a similar synchronization framework to form an output composite video signal, but with segments in said different sequence.

Claim 9

A method for encryption/decryption processing of an input composite video signal which comprises segments of video information within successive time slots in a synchronization framework defined by sychronization information contained by the signal, sid method comprising: separating said segments of video information from said sychronization framework; writing said successive segments into locations in a memory device addressed according to a randomly time-varying sequence; reading said segments from locations in said memory device addressed according to a different sequence, each segment of video information read from an addressed location in the memory being replaced by a next segment to be written into the memory; and reintegrating said segments into a similar synchronization framework to form an output composite video signal, but with segments in said different sequence.