说明：  QPSK即四进制移向键控（Quaternary Phase Shift Keying），它利用载波的四种不同相位来表示数字信息，由于每一种载波相位代表两个比特信息，因此每个四进制码元可以用两个二进制码元的组合来表示。
(I.e., quaternary toward keying QPSK (Quaternary Phase Shift Keying), which uses the carrier to represent the four different phases of digital information, the phase of each carrier representative of two bits of information, so that each symbol may quaternary with a combination of two binary symbols to represent.)