Importance

Loading Importance Indicators...

Abstract

A voice privacy system enhances the privacy of a transmission by disguising the amplitude characteristics and cadence content of transmitted voice signals. Encoding apparatus first divides a voice signal to be transmitted into two or more frequency bands. One or more of the frequency bands is frequency inverted, delayed in time relative to the other frequency bands and then recombined with the other frequency bands to produce a composite signal for transmission to a remote receiver. By selecting the magnitude of the delay to approximate the time constants of the cadence, or intersyllabic and phoneme generation rates, of the speech to which the voice signal corresponds, the amplitude fluctuations of the composite signal are substantially lessened and the cadence content of the signal is effectively disguised. It thus becomes extremely more difficult for unauthorized listeners to extract cadence information from the signal as a means of extracting intelligence from the signal. Decoding apparatus at the receiver reconstitutes the original voice signal.

Loading the Abstract Image...

First Claim