QPSK

代码说明：

  数字调制就是把数字基带信号的频谱搬移到高频处，形成适合在信道中传输的带通信号。基本的数字调制方式有振幅键控（ASK）、频移键控（FSK）、绝对相移键控（PSK）、相对（差分）相移键控（DPSK）。在接收端可以采用想干解调或非相干解调还原数字基带信号。 (Digital modulation is the spectrum shifting to high frequency digital baseband signals, suitable for the formation of bandpass signal transmission in the channel. Digital modulation basic amplitude keying (ASK), frequency shift keying (FSK), the absolute phase shift keying (PSK), relative (differential) phase shift keying (DPSK). At the receiving end can be used to dry the demodulation or non coherent demodulating the digital baseband signal. )