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Class Information
Number: 380/39
Name: Cryptography > Communication system using cryptography > Frequency shift or inversion > Having plural band pass filters
Description: Subject matter which divides the signal into a plurality of subbands by filtering prior to a frequency shift or inversion.
Patents under this class:
| Patent Number |
Title Of Patent |
Date Issued |
| 7051203 |
Data watermarks created by using an uneven sampling period |
May. 23, 2006 |
| 6823026 |
Apparatus and method for baseband detection |
Nov. 23, 2004 |
| 6570988 |
Simple technique for implementing a cryptographic primitive using elementary register operations |
May. 27, 2003 |
| 5991416 |
Scrambling and descrambling circuit for a cordless telephone |
Nov. 23, 1999 |
| 5796838 |
Method and apparatus for performing frequency spectrum inversion |
Aug. 18, 1998 |
| 5471531 |
Method and apparatus for low cost audio scrambling and descrambling |
Nov. 28, 1995 |
| 5446795 |
Universal decoder for television signal scramble systems |
Aug. 29, 1995 |
| 5235640 |
Master decoder for television signal scramble systems |
Aug. 10, 1993 |
| 5150401 |
Retrofittable encryption/decryption apparatus using modified frequency modulation |
Sep. 22, 1992 |
| 5065430 |
Voice band splitting scrambler |
Nov. 12, 1991 |
| 5018198 |
Speech privacy processing method and apparatus therefor |
May. 21, 1991 |
| 4984219 |
Method and apparatus for decoding of frequency inversion based scramblers |
Jan. 8, 1991 |
| 4949378 |
Toy helmet for scrambled communications |
Aug. 14, 1990 |
| 4924512 |
Method and apparatus for preventing recognition of a telephone dialing signal |
May. 8, 1990 |
| 4817141 |
Confidential communication system |
Mar. 28, 1989 |
| 4802219 |
Method and apparatus for distorting a speech signal |
Jan. 31, 1989 |
| 4799257 |
Wireless transmission system for PM modulation signal |
Jan. 17, 1989 |
| 4790009 |
Scrambler system |
Dec. 6, 1988 |
| 4773092 |
Speech scramblers |
Sep. 20, 1988 |
| 4652699 |
Voice scrambler using frequency-inversion and band-splitting technique |
Mar. 24, 1987 |
| 4623980 |
Method of processing electrical signals by means of Fourier transformations |
Nov. 18, 1986 |
| 4232194 |
Voice encryption system |
Nov. 4, 1980 |
| 4195202 |
Voice privacy system with amplitude masking |
Mar. 25, 1980 |
| 4188506 |
Method and installation for masked speech transmission over a telephone channel |
Feb. 12, 1980 |
| 4160875 |
Security system |
Jul. 10, 1979 |
| 4107470 |
Digital SSB-FDM communication system derived from a complex band-pass digital filter bank and by a filter breakdown process |
Aug. 15, 1978 |
| 4068094 |
Method and apparatus for the scrambled transmission of spoken information via a telephony channel |
Jan. 10, 1978 |
| 4020285 |
Voice security method and system |
Apr. 26, 1977 |
| 4013837 |
Voice security method and system |
Mar. 22, 1977 |
| 3995115 |
Speech privacy system |
Nov. 30, 1976 |
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