标题调制解调器(MODEM)

　　Contraction of modulator/demodulator，a device that allows a computer to transmit information over a telephone line. The modem translates between the digital signals that the computer uses，and analog signals suitable for transmission over telephone lines. When transmitting，the modem modulates the digital data onto a carrier signal on the telephone line. When receiving，the modem performs the reverse process，and demodulates the data from the carrier signal. Modems usually operate at speeds ranging from 1200 to 9600 baud over standard telephone lines，and can use rates up to 19200 baud over leased lines. A suitable communications program is needed to operate the modem.
　　MODEM是调制器和解调器的英文缩写，它是一种允许计算机通过电话线传输信息的装置。调制解调器用于在计算机使用的数字信号和适于在电话线上传送的模拟信号之间进行转换。当传送数据时，调制解调器把数字数据进行调制加到电话线上的载波信号上。当接收数据时，调制解调器执行相反的过程，把数据从载波信号中解调出来。调制解调器在标准电话线路上的传送速度通常为1200波特至9600波特，而在租用的专线上传输速率可以高达19200波特。要使调制解调器工作还需要合适的通讯程序。