| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable rate voice coding system which is adaptable for a communication system using an adaptive modulation system varying a transmission rate corresponding to variation of a condition of a transmission path and in which speech quality is hardly influenced by the variation of a transmission rate. SOLUTION: In a transmission side, plural frames of an input signal a2 is coded, and coded voice information in which the signal is divided into core information and enhancement information of plural stages is made. When a transmission rate of the present frame is the maximum speed, a part of information of the present frame is canceled, a part of information of the next frame is allotted and sent out, when a rate of the next frame is low, only a part of information is sent out. In a receiving side, only the information of the present frame is decoded for the present frame, for the next frame, a part of information of the next (present) frame and a part of information already sent at the time of the present (before) frame are synthesized, and it is decoded. |
