直接序列扩频通信可以有效地抵抗来自信道中的窄带干扰。在一个直扩通信系统中,扩频是通过伪噪声序列(PN)对发送的信息数据进行调制来实现的。在接收端,原伪噪声序列和所收信号的相关运算可将窄带干扰扩展到DS信号的整个频带,使干扰等效为幅度较低频谱较平坦的噪声；同时，将DS信号解扩,恢复原始信息数据。-direct sequence spread spectrum communication can be effective resistance from the channel narrowband

　　网站安全是指出于防止网站受到外来电脑入侵者对其网站进行挂马，篡改网页等行为而做出一系列的防御工作。-Web site security is that the prevention by external sites linked to its computer intruders horse, acts of tampering with web pages, make a series of defensive work.