说明：  2FSK（Frequency Shift Keying）为二进制数字频率调制（二进制频移键控），用载波的频率来传送数字信息，即用所传送的数字信息控制载波的频率。2FSK信号便是符号“0”对应于载频 f1，而符号“1”对应于载频 f2（与 f1 不同的另一载频）的已调波形，而且 f1 与 f2 之间的改变是瞬间的。传“0”信号时，发送频率为 f1 的载波； 传“1”信号时，发送频率为 f2的载波。可见，FSK 是用不同频率的载波来传递数字消息的。
(2FSK (frequency shift keying) is binary digital frequency modulation (binary frequency shift keying). The carrier frequency is used to transmit digital information, that is, the carrier frequency is controlled by the transmitted digital information. The convenience of 2FSK signal is that symbol "0" corresponds to carrier frequency f1, while symbol "1" corresponds to modulated waveform of carrier frequency f2 (another carrier frequency different from f1), and the change between F1 and F2 is instantaneous. When transmitting the "0" signal, the carrier with the transmission frequency of F 1; when transmitting the "1" signal, the carrier with the transmission frequency of f2. It can be seen that FSK uses different frequency carriers to transmit digital information.)