| 摘要 |
A digital speech-band spectrum inversion apparatus for use in a cordless telephone system provides transmission security of the voice signal between the handset (10) and the base station (18). The apparatus includes an A/D converter (24) for converting an input analog voice-band signal to a digital signal, a digital signal processor (30) for modifying the digital signal in accordance with a prescribed algorithm, and a D/A converter (32) for converting the modified digital signal to an output analog signal, the output analog signal being inverted in frequency spectrum from the input analog signal. A/D converter (24) samples the input analog signal at a periodic rate, and converts the sampled voltage levels to digital representations thereof. The algorithm performed by the digital signal processor (30) computes the two's complement inversion of the digital representations of alternate samples of the input analog signal.
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