()in the strength of the carrier signal is

问题单项选择题

()in the strength of the carrier signal is varied to represent binary 1 or 0．______is a system that can map a name to an address and conversely an address to an name．______is a three-way handshaking authentication protocol that it’s packets are encapsulated in the point-to-point protocol______is an approach that enables an ATM Switch to behave like a LAN switch．______is an guided media which is made of glass or plastic and transmits signals in the form of light．

A．ASK

B．PSK

C．FSK

D．FDM

答案

参考答案：A

解析：

在幅频键控(ASK)调制中，载波的振幅随所表示的0、1变化；DNS是一种能够将名字映射为IP地址同时也可以将IP地址映射为名字的系统；CHAP是一种利用三次握手机制的认证协议，它的数据包被封装在点对点链路协议上；LANE是一种能够让ATM交换机象局域网交换机一样的方式；光纤是一种用玻璃纤维和塑料外套制成的传输介质，它上面以光的形式来传输信号。