Cryptography – Key management – Having particular key generator
Patent
1986-11-21
1990-10-16
Tarcza, Thomas H.
Cryptography
Key management
Having particular key generator
380 11, 380 17, 358 19, 358144, 358150, 375 18, H04N 7167, H04N 945, H04N 704
Patent
active
049641620
ABSTRACT:
A television signal encoding and decoding system providing a line-spin scrambled video signal with substantially reduced amplitude gaps and line tilt and a digitally-encrypted audio signal that can be transmitted within the bandwidth limitations of a conventional NTSC television signal. The television signal encoding system, located at a television transmitter, includes a video and an audio encoder. The video encoder selectively line spin scrambles, reverses and inverts certain video lines or video line segments to generate a line-spin scrambled video signal having amplitude gaps less than some desired value. The audio encoder digitally encrypts the audio signal and modulates the encrypted audio signal with a three-level partial response waveform to generate and encrypted audio signal that can be transmitted within the bandwidth limitations of a conventional NTSC television signal. The television signal decoding system, located at a television receiver, includes a video and an audio decoder. The video decoder applies line tilt compensation to the received line-spin scrambled video signal and then unscrambles the compensated scrambled video signal. The audio decoder demodulates and decrypts the received audio signal.
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Baxes, Gregory A., "Digital Techniques Cure Line Segmentation Scrambling Problems," NCTA technical paper presented at Las Vegas Convention, Jun. 2-5, 1985, pp. 308-313.
McAdam Peter L.
Schnerk Thomas G.
Shreve Gregory A.
Goldstein Sol L.
Tarcza Thomas H.
TRW Inc.
Wallace Linda J.
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