A single chip LPC vocoder

Abstract

A DIGITAL MOS-LSI circuit which implements a full-duplcx speech analysis/synthcsis system will be reported. This vocodcr IC analyzes speech in realtime, generating a low-bit-rate digital data stream suitable for transmission or storage. Simultaneously, syntllesized spccch can be generated from an incoming data stream. Vocoders transmit two types of informalion: spectral parameters and excitation parameters. The vocodcr IC uses linear predictive coding(LPC) to reprcsent the spectrum. The excitation is represented by its energy, a voiced/unvoiced decision, and the period of the pitch fundamental.