USA As Represented by Secretary of the Navy

General Instrument Corporation Jerrold Communications

David E Zeidler

John T Griffin

Keith S Rizkowski

A method and apparatus for scrambling video signals to obtain the secure transmission of video information. A block of video lines in a television raster is divided into top and bottom sub-block portions. The top and bottom sub-block portions are switched in position. The sequence of video lines within the sub-blocks are shuffled so that the resulting scrambled video signal contains blocks of video lines which have been block portion switched and shuffled from their original block portion position and their original line sequences. The size of the first block of video lines can grow and/or shrink in time so that the video appears to roll down or up the display. A pseudo-random number of sequence controls the shuffling sequence. A descrambler receives the scrambled video signal and a code identifying the shuffling sequence of the scrambled video for descrambling the video signal and returning the block portions and the video lines to their original sequences.

Method and apparatus for television signal scrambling using block

This invention discloses electronic circuit that can be either embedded in n oceanographic sonobuoy housing or used as stand-alone equipment and which establishes and generates sonar signals of a repetition rate, pulse length, and amplitude pulse shape which are all programmably variable, selectable and determinable. A plurality of predetermined sonar pulse 'profiles' are stored in a read only memory (ROM). A particular profile is selected from this memory and this profile is generated point by point at a selected frequency.

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Hatboro, PA, United States of America

David E Zeidler