说明：  卷积码是一种有记忆的编码，在任意给定的时间单元处，编码器的n个输出不仅与此时间单元的k个输入有关，而且也与前m个输入有关。卷积码通常表示为：（n,k,m） 本次仿真采用（2，1，3）卷积码。
(convolutional code is a kind of code memory, in any given unit of time, the encoder output n this time not only with the elements of the k input, but also with the input m. Convolutional codes are usually stated as : (n, k, m), the simulation used (2,1,3) convolutional code.)