Cryptography – Communication system using cryptography – Time segment interchange
Patent
1987-10-30
1989-07-25
Buczinski, Stephen C.
Cryptography
Communication system using cryptography
Time segment interchange
380 33, 380 40, 380 41, 380 43, 380 46, 380 48, H04K 104, H04K 106, H04K 110, H04K 902
Patent
active
048521663
ABSTRACT:
An analogue scrambling system with dynamic band permutation in which the speech signal is filtered (1), sampled (2) at the rate f.sub.e, digitized (3), transformed by means of an analysis filter bank (4) into N sub-band signals sampled at f.sub.e /N and transferred in a permuted order to a synthesis filter bank (13) accomplishing the calculations of the scrambled signal sampled at the rate f.sub.e. A set of permutations is protected in a memory (8) and a scrambling with dynamic permutation in time is obtained by changing the read addresses of the memory. The scrambled signal reconverted into an analogue signal (14, 15) is transmitted through an analogue channel to an unscrambler where it is preprocessed so that the synchronizing and equalizing functions are accomplished and where the accomplished processes are identical with those accomplished in the scrambler, the difference being that the permuted order of the N sub-band signals is restored.
REFERENCES:
patent: 3991271 (1976-11-01), Branscome et al.
patent: 4068094 (1978-01-01), Schmid et al.
patent: 4188506 (1980-02-01), Schmid et al.
patent: 4221931 (1980-09-01), Seiler
patent: 4525844 (1985-06-01), Scheuermann
patent: 4551580 (1985-11-01), Cox et al.
patent: 4663500 (1987-05-01), Okamoto et al.
patent: 4747137 (1988-05-01), Matsunaga
Buczinski Stephen C.
Lobato Emmanuel J.
Telecommunications Radioelectriques et Telephoniques T.R.T.
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