在普通电话线路上作数字数据传输,需要在其发送端装设一个调制器,将数据脉冲流转换成易于发送的形式并使之耦合到电话线路上。一种适用于话音电话线路上使用的手段就是移频键控或FSK调制。1200比特的数据速率是话音线路移频键控的实际极限。调制器必须在这种速率下工作并适于电话线路的接线以及适于通过电话 For digital data transmission over regular telephone lines, a modulator needs to be installed at its transmit end to convert the stream of data pulses into an easy-to-send form and couple it to the telephone line. One method that is suitable for use on voice telephone lines is frequency shift keying or FSK modulation. The data rate of 1200 bits is the actual limit of voice line frequency shift keying. The modulator must work at this rate and be suitable for the wiring of telephone lines and for telephone over the telephone