MSK is a kind of Frequency Shift Keying (FSK) with continuous phase.MSK signals have constant envelope,and its coherent detection performs better than other FSK schemes. When tilted phase concept is introduced, the phase trellis exhibits time invariance just as convolutional codes.So the Viterbi algorithm turns out to be the optimal demodulation method.Analysis and simulation show that assuming perfect phase and time synchronization, the maximum likelihood detection based on Viterbi algorithm performs better,and is the optimal demodulation for MSK.Only coherent detection of signals transmitted over an AWGN (Additive White Gaussi⁃an Noise) channel is considered here.%最小频移键控（ Minimum Shift Keying， MSK）是一种连续相位的频移键控。 MSK信号包络恒定，相干检测时的误码率性能比一般的频移键控要好。 MSK在引入倾斜相位的概念后，其相位格图类似于卷积码的时不变网格图，因此能用Viterbi算法实现最优解调。理论分析和数值模拟表明，在相位与时间严格同步的条件下， MSK基于Viterbi算法的最大似然检测法性能更好，是最优的解调方法。这里仅考虑在加性高斯白噪声信道下信号传输的相干检测。
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