Abstract: For the shortcoming of differential MSK demodulator that can not concatenate SISO decoder since the output being hard information，according to the characteristics of differential encoding，a soft demodulation algorithm of differential MSK combining sign extraction and amplitude weighting is proposed.With Turbo codes as channel coding scheme，combined with differential MSK modulation，the system simulation model is established.Simulation results show that the algorithm can effectively reduce the decision loss of iterative systems.The application of differential coding overcomes the phenomenon of inverting π in carrier synchronization technology.

Key words: differential MSK, Turbo codes, soft demodulation, SISO decoder

摘要： 针对差分MSK解调输出硬信息，无法与SISO译码器进行级联的缺点，根据差分编码的特点提出了符号提取与幅度加权相结合的差分MSK软解调算法。以Turbo码为信道编码方案，结合差分MSK调制解调方式，建立系统仿真模型。仿真结果表明，该算法能有效减小迭代系统中的判决损失。差分编码的应用，也克服了载波同步技术中的倒π现象。

关键词: 差分MSK, Turbo码, 软解调, SISO译码器