说明：  正交相移键控（Quadrature Phase Shift Keyin，QPSK）是一种数字调制方式。它分为绝对相移和相对相移两种。由于绝对相移方式存在相位模糊问题，所以在实际中主要采用相对移相方式DQPSK
(QPSK SIMULATION Orthogonal phase shift keying (Quadrature Phase Shift Keyin, QPSK) is a digital modulation method. It is divided into two kinds: absolute phase shift and relative phase shift. As the phase ambiguity problem exists in the absolute phase shift mode, the relative phase shift mode DQPSK is used in practice.)