香农第一定理指出了平均码长与信源之间的关系，同时也指出了可以通过编码使平均码长达到极限值，这是一个很重要的极限定理。-Shannon first theorem that the average yards long with the letter of the relationship between the source, it has also pointed out the code can make the average yards long reach limits, this i

计算熵值，互信息 自信息 香农编码 费诺编码 包含源代码-Calculate the entropy, mutual information contains the source code from the information the Shannon encoded Fenno coding

典型的Turb。码是一类并行级联的系统卷积码，当交织长度足够长时，其性能可逼 近仙农限。-Typical Turb. Code is a class of parallel concatenated convolutional codes of the system, when the cutting length for long enough, its performance can be close to Shannon limit.