Communication system capable of improving a speech quality by effectively calculating excitation multipulses

Abstract From the Canadian patent

In an encoder device for encoding a sequence of digital speech signals classified into a voiced sound and an unvoiced sound into a sequence of output signals by the use of a spectrum parameter and pitch parameters at every frame having N samples where N represents an integer, a judging circuit judges whether the digital speech signals are classified into the voiced sound or the unvoiced sound to produce a judged signal representative of a result of judging. A processing unit processes the digital speech signals in accordance with the judged signal to selectively produce a first set of primary sound source signals and a secondary sound source signals. The first set of primary sound source …