Secret speech equipment
US4959863A · kind A · utility
18Cited by
10References
15Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 2, 1988 |
| Grant date | Sep 25, 1990 |
| Priority date | — |
| Expiry date | Jun 2, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04K1/04
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Disclosed is a secret speech equipment for ensuring the secrecy of an analog voice signal, and used in voice communication systems such as an analog telephone and mobile radio. The equipment comprises a sub-band signal generating unit for treating input digital samples as frequency-multiplexed signals of voice spectra, to split the frequency-multiplexed signals into a plurality of frequency bands, and thus obtain sub-band signals of the frequency bands, a sub-band signal permutating unit for permuting the sequence of the sub-band signals, and a sub-band signal multiplexing unit for multiplexing the permutated sub-band signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.