16kbps　CVSD与64kbps　PCM编码数字转换算法

The Code Conversion Algorithm Between 16kbps CVSD and 64kbps PCM

本文提出了１６ｋｂｐｓ连续可变斜率增量调制（ＣＶＳＤ）与６４ｋｂｐｓＡ律ＰＣＭ编码数字转换算法，在无传输误码情况下，采用该转换算法，（１）从ＣＶＳＤ转换到ＰＣＭ时，同直接ＣＶＳＤ编码相比，分段信噪比（ＳＮＲＳＥＧ）恶化小于０．１ｄＢ，信噪比（ＳＮＲ）恶化小于０．０１ｄＢ，多次转换（转换次数≥２）时ＳＮＲ和ＳＮＲＳＥＧ保持不变，即无误差积累；（２）从ＰＣＭ转换到ＣＶＳＤ时，同直接ＣＶＳＤ编码相比，ＳＮＲ和ＳＮＲＳＥＧ有所提高，多次转换时ＳＮＲ和ＳＮＲＳＥＧ同样保持不变。这一算法的提出解决了我国专用网（ＣＶＳＤ信源编码）与公众网（ＰＣＭ信源编码）互联中信源编码变换的方案。

A digital code conversion algorithm between 16kbps CVSD(Continuously Variable Slope Delta)and 64kbps A-law PCM is proposed in this paper,which eliminates cumulative distortion regardless of the number of the tandem transcodings in the steady state mode. Thus,the algorithm can enhance the performance of the telephone network linking between the special network and civil network.