6.75kbit/s码激励线性预测编码器

6.75 kb/s Codedexcited Linear Prediction Coder—— A Scheme for GSM Half-rate Coding

提出用码激励线性预测（ＣＥＬＰ）实现ＧＳＭ半速率编码器的一种方案。该方案把中心削波和结构化码本相结合，并推导了加权滤波器响应的公式，使码本搜索的计算量大大降低，存储量显著减少，并获得高质量语音。计算机模拟结果表明，本方案编码速率为６７５ｋｂｉｔ／ｓ，合成语音ＭＯＳ得分为３５ｄＢ～４０ｄＢ。该方案可以在一块ＴＭＳ３２０Ｃ３０上实时实现。

Digital mobile communication systems are developing very fast, and the speech compressed coding is one of its key techniques. In this paper, a scheme for the GSM half-rate system is presented. By using the overlapping centerclipped codebook, the complexity and memory cost are reduced greatly while the quality of the synthetic speech is still high. Computer simulation shows that the bit rate of the coder version is 6.75 kb/s and the MOS of the synthetic voice is 3.5～4.0. Because of its advantages of low complexity, low storage and high quality, it can be realized on one TMS320C30.