问题
单项选择题
In (66) the strength of the carrier signal is varied to represent binary 1 or 0. (67) is a system that can map a name to an address and conversely an address to al name. (68) is a three-way handshaking authentication protocol that it’s packets are encapsulated in the point-to-point protocol. (69) is an approach that enables an ATM switch to behave like a LAN switch. (70) 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：本题主要考查调制的专业术语。ASK为幅度键控，PSK为移项键控的英文缩写，FSK为移频键控的英文缩写，FDM为频分多路复用的英文缩写。答案为A。