Cryptography – Key management – Having particular key generator
Patent
1988-09-07
1990-02-13
Buczinski, Stephen C.
Cryptography
Key management
Having particular key generator
380 19, H04N 7167
Patent
active
049013513
ABSTRACT:
A transmitter encoder has a gain selector for compressing the level of a horizontal sync signal component of a video intermediate frequency (IF) signal to scramble it, and an AM modulation degree controller for superposing a control signal, which indicates the timing for the level compression, on an FM audio IF signal in the form of AM modulation. The transmitter encoder further has an oscillator circuit for generating a sine wave with a horizontal frequency (fH) and an nfH sine wave having a frequency n times the horizontal frequency, and a mixer for mixing these sine waves to thereby provide the above control signal. A receiver decoder has an AM detector for detecting an AM component of the FM audio IF signal from the transmitter encoder to reproduce a composite signal and band filters for respectively extracting the fH and nfH sine waves from the reproduced composite signal. The receiver decoder further has a gain selector for expanding the compressed level of the horizontal sync signal component of the video IF signal from the transmitter encoder, by means of a sync expansion pulse generated on the basis of the fH sine wave.
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Kuroiwa Wataru
Maeda Jyoji
Masuko Akinori
Tanaka Masatoshi
Uehara Shouji
Buczinski Stephen C.
Gregory Bernarr Earl
Kabushiki Kaisha Toshiba
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