理解通信系统特别是无线通信系统对基带信号的处理方法及目的，包括基带系统的差错控制，扩频跳频原理，保密通信等基本原理和实现方法。

-Understanding of communication systems, especially wireless communications system to the base-band signal processing methods and purposes, including base-band system for error control, spread spectrum frequency hopping principle of confidentiality of communications, such as the basic principle and method.