中文说明：
伪随机码或称PN码，是扩频通信中不可缺少的一种序列。扩频通信，简单的说来就是通过一组相关性很强的伪随机序列，使原有的信号按照伪随机序列的特性出现。
English Description：
Pseudo random code or PN code is an indispensable sequence in spread spectrum communication. Spread spectrum communication, in short, is to make the original signal appear according to the characteristics of pseudo-random sequence through a group of pseudo-random sequences with strong correlation