The Research,Design and Application of Adaptive Pulse Code Modulation Speech Codec

• Main Authors: Wu, tsong-nan, 吳聰男
• Other Authors: Yu tsai-chung
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/81556512688010405338

碩士 === 淡江大學 === 電機工程學系 === 84 === The speech application are very popular in the world today, such as telephone,voice mail box,speech recognition,speech synthesis...etc.The amout of orginal speech data is very large. If we don't process those stored speech data , it must cost much memory.For example,if we record speech signal with 8 KHZ sampling rate and 8 bits per sample,we need 64k bits memory per second and 3.84 Mbits per minute . In the region of speech coding, people try to reduce the bit rate of speech data and make reconstructed signal comfortable for people.This paper focuses on using less bit rate to implement speech application. Sound baster is used to record speech signal and Adaptive Differential Pulse Code Modulation (ADPCM ) bases on International Telegraph and Telephone Consultative Committee (CCITT) G.721 standard is adopted to compress speech data in this paper.The sampling rate is 8 KHZ and 4 bits per sample. In ADPCM system , one word memory adaptive quantizer and adaptive preditor is adopted to reduce bit rate in this paper. In the decoder of ADPCM , a 8-bit mircocontroller is adopted to implement this algorithm.Besides,the paper use verilog to simulate the interface between the mircocontroller,memory and D- to-A converter.After finishing all simulation,the paper uses FPGA to verify whole system in real world. Besides,this paper design a simple application using this speech decoder to make sure the quantity of output speech accepted by the people.