Method and system for scrambling and descrambling audio information signals
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United States of America Patent
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-
Oct 15, 1991
Grant Date -
N/A
app pub date -
Jun 15, 1989
filing date -
Jun 15, 1989
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Audio signals are scrambled by inverting the original; frequency spectrum so that frequency portions originally lying at the lower end of the audio frequency band are shifted to the upper end while those portions originally lying near the upper end of the band are shifted to the lower end. A pilot tone of known frequency is recorded along with the frequency shifted audio signals, along with accompanying video signal portions. Upon reproduction, any variations in phase and frequency introduction by the recording or reproduction process are tracked by the pilot tone, which is used to generate the demodulation signal for restoring the original frequency content of the audio signals.
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