说明：  对（7，4）循环码的误码率进行了matlab的仿真，通过对比两条曲线，直观对比出未经过信道编码和经过信道编码的误码率比较。
(Of (7,4) cyclic code error rate of the matlab simulation, by comparing the two curves, a direct comparison has not been after channel coding and channel coding the bit-error rate.)