用Viterbi译码的方法进行解码，其中的编解码全部自己编写代码(S-Function方式)，在加性白高斯噪声信道中，画出比特信噪比与误码率的关系曲线。-With Viterbi decoding method of decoding, encoding and decoding them all to write your own code (S-Function mode), the additive white Gaussian noise channel, signal to noise ratio and bit error rate to draw the curve.