中文说明：
数字频率调制又称频移键控（FSK），二进制频移键控记作2FSK。数字频移键控是用载波的频率来传送数字消息，即用所传送的数字消息控制载波的频率。2FSK信号便是符号“1”对应于载频，而符号“0”对应于载频（与不同的另一载频）的已调波形，而且与之间的改变是瞬间完成的。
English Description：
Digital frequency modulation is also called frequency shift keying (FSK), and binary frequency shift keying is recorded as 2FSK. Digital frequency shift keying uses the frequency of the carrier to transmit digital messages, that is, the frequency of the carrier is controlled by the transmitted digital messages. 2FSK signal is that the symbol "1" corresponds to the carrier frequency, and the symbol "0" corresponds to the carrier frequency (different from another carrier frequency), and the change between and is completed instantaneously