利用电话线路进行计算机通讯,其中要解决的问题是数字信号在电话线路中的传输,因此人们研制出了调制解调器这一专用设备,它将计算机发出的数字信号调制成模拟信号输入电话线,而将电话线传入的模拟信号再解调成数字信号输入计算机,其作用如图所示: The use of telephone lines for computer communications, of which the problem to be solved is the transmission of digital signals over telephone lines, so that people have developed a special device for modems, which converts a digital signal from a computer into an analog signal to a telephone line, The incoming analog signal on the telephone line is then demodulated into a digital signal which is input to the computer as shown in the figure below: