Cryptography – Cryptanalysis
Patent
1988-07-20
1990-02-27
Cangialosi, Salvatore
Cryptography
Cryptanalysis
380 8, 380 19, 380 36, 380 46, H04K 104
Patent
active
049052780
ABSTRACT:
In a system in which an audio signal is scrambled by being divided into blocks each comprising a plurality of segments, and the segments are re-ordered within the blocks to provide the scrambled signal, the joins between the segments are required to be located at a descrambler. To enable the joins to be located, a framing sequence is added to the signal in synchronism with the segments and which consists of a low-level signal having a frequency spectrum which is substantially similar to the spectrum of the audio signal. Preferably a pseudo-random binary sequence is used having typically 200 to 500 bit periods per segment.
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British Broadcasting Corporation
Cangialosi Salvatore
O'Connell Robert F.
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