[54] METHOD AND APPARATUS FOR
CREATING ENCRYPTED AND DECRYPTED
TELEVISION SIGNALS
[75] Inventors: John D. Lowry, Toronto; Keith
Lucas, Oak Ridges, both of Canada
[73] Assignee: Scientific Atlanta, Inc., Atlanta, Ga.
[21] Appl. No.: 736,301
[22] Filed: May 21,1985
Related U.S. Application Data
[63] Continuation-in-part of Ser. No. 507,565, Jun. 24, 1983.
[51] Int. CI." H04N 7/167; H04N 11/06
[52] U.S. CI 380/11; 358/12;
380/20
[58] Field of Search 358/120, 123, 12, 114,
358/119
[56] References Cited
U.S. PATENT DOCUMENTS
2,547,598 4/1951 Roschke 358/124
2,673,237 3/1954 Reeves 358/120
2,677,719 5/1954 Reeves 358/119
2,961,481 11/1960 Hammond, Jr. et al 358/119 X
2,972,008 2/1961 Ridenour et al 358/123
3,735,027 5/1973 Corwin et al 358/114
4,070,693 1/1978 Shutterly 358/123
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4,330,794 5/1982 Sherwood 358/120
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4,338,628 7/1982 Payne et al 358/120
4,390,898 6/1983 Bond et al 358/119
4,396,946 8/1983 Bond 358/119
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FOREIGN PATENT DOCUMENTS
642144 6/1962 Canada 358/119
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OTHER PUBLICATIONS
Den Toonder et al, United Kingdom Patent Application No. 2,078,051, Dec. 23, '81. Den Toonder et al, United Kingdom Patent Application No. 2,077,547, Dec. 16, '81. W. Cheung, United Kingdom Patent Application No. 2,042,846, Dec. 24, '80.
Fondse et al, United Kingdom Patent Application No. 2,038,137, Jul. 16, '80.
Primary Examiner—Stephen C. Buczinski
Assistant Examiner—Linda J. Wallace
Attorney, Agent, or Firm—Banner, Birch, McKie &
Beckett
[57] ABSTRACT
A method and apparatus for creating a television signal and encrypting or decrypting the signal at the same time. Luminance and chrominance information are received by the apparatus and stored in separate television scan line stores. The stored liminance and chrominance information is read out from their respective stores at a frequency corresponding to a desired format or standard to create the television signal. The signal may be simultaneously encrypted or decrypted by delaying the time at which the luminance and/or chrominance information is read out in accordance with an encryption or decryption key.
24 Claims, 19 Drawing Figures
