FULL-DUPLEX DIGITAL VOCODER, PART I.
TEXAS INSTRUMENTS INC DALLAS
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This report presents the results of the design, development, and manufacture of a polymodal, full-duplex, digital vocoder system. This vocoder equipment provides the user with a choice of five primary modes of operation. These five modes consist of three digital transmission rates 1200, 2400, and 9600 bps and four degrees of speech intelligibility, voice quality, and talker recognition. This equipment was developed for two primary purposes first, to provide an experimental polymodal vocoder flexible enough to meet a wide variety of requirements, and second, to provide a research tool for studies and evaluation of various innovations in vocoder design. Spectrum-normalizing techniques used in this system provide more effective quantization of spectrum data and allow fewer bits per second in specifying these data. Various optional modes of operation have been incorporated which increase the flexibility of the system. Fully automatic bit and frame synchronization is used. An all-digital technique of pitch pulse code modulation encoding decoding has been designed that provides rapid and accurate conversion of the pitch frequency information to digital data. Author