| 摘要 |
PURPOSE:To avoid a problem such as the deterioration in the articulation of a demodulated voice attended with the modulation-demodulation system by multiplying in-phase components and orthogonal components of an input signal and a random signal, compressing the amplitude component of the input signal nonlinearly and multiplying the result to the sum of the said product so as to generate a privacy call signal. CONSTITUTION:A voice input signal v (t) is sampled by an analog/digital (A/D) conversion section 1 and converted into an orthogonal signal by an orthogonal filter section 3 through a band limit filter (BPF1) 2. The random signal is converted into an orthogonal signal by a random signal orthogonal section 11, the product between the in-phase component of the input voice signal and the in-phase component of the random signal, and the product between the orthogonal component of the input voice signal and the orthogonal component of the random signal are calculated by product modulation sections 12, 13, the sum of both the products is calculated by a synthesis section 14, and the envelope component of the input voice signal extracted by an amplitude component extraction section 4 is subject to nonlinear compression by a compression section 35 to calculate the product of the output of the synthesis section 14.
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