说明：  一个基本利用simulink实现的扩频通信系统，包含扩频、调制、解扩、解调，可以比较全面的了解扩频系统的组成。
(Simulink realization of a basic use of spread-spectrum communication systems, including spread spectrum, modulation, despreading, demodulation, can be a more comprehensive understanding of the composition of spread-spectrum systems.)