An analog speech scrambler using the FFT technique with high-level security

Author

Matsunaga, Akira ; Koga, Keiichiro ; Ohkawa, Michihisa

Author_Institution

Kokusai Denshin Denwa Co. Ltd., Japan

fYear

1988

fDate

12-15 June 1988

Firstpage

1619

Abstract

A full-duplex analog speech-scrambling system is proposed for the application to mobile communication systems and public-switched telephone networks. The scrambling algorithm is based on the rearrangement of the fast Fourier transform (FFT) coefficients accompanied by adaptive dummy spectrum insertion and companding operations. Simulations results indicate that the scrambled speech has no residual intelligibility and the unscrambled speech quality is satisfactory. The hardware unit is implemented by using seven advanced digital signal processing (DSP) chips, including those for an echo canceller for full-duplex operation and an adaptive equalizer.<>

Keywords

fast Fourier transforms; mobile radio systems; radiotelephony; security of data; signal processing; telephone station equipment; DSP chips; FFT coefficients; adaptive dummy spectrum insertion; adaptive equalizer; analog speech scrambler; digital signal processing; echo canceller; fast Fourier transform; full-duplex system; mobile communication systems; public-switched telephone networks; scrambled speech; scrambling algorithm; security; simulation results; unscrambled speech quality; Communication system security; Cryptography; Fast Fourier transforms; Frequency; Hardware; Modems; Signal processing algorithms; Speech codecs; Speech processing; Telephony;

fLanguage

English

Publisher

ieee

Conference_Titel

Communications, 1988. ICC '88. Digital Technology - Spanning the Universe. Conference Record., IEEE International Conference on

Conference_Location

Philadelphia, PA, USA

Type

conf

DOI

10.1109/ICC.1988.13822

Filename

13822