Title :
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
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;
Conference_Titel :
Communications, 1988. ICC '88. Digital Technology - Spanning the Universe. Conference Record., IEEE International Conference on
Conference_Location :
Philadelphia, PA, USA
DOI :
10.1109/ICC.1988.13822
