QAM是一种矢量调制，将输入比特先映射（一般采用格雷码）到一个复平面（星座）上，形成复数调制符号，然后将符号的I、Q分量（对应复平面的实部和虚部，也就是水平和垂直方向）采用幅度调制，分别对应调制在相互正交（时域正交）的两个载波（cos wt和sin wt）上-QAM is a modulation vector, the first mapping the input bits (Gray code commonly used) to a complex plane (constellation), the formation of complex modulation symbols, then symbols I, Q components (corresponding to the complex plane of the real and imaginary parts , that is, horizontal and vertical) using amplitude modulation, corresponding to the modulation in the orthogonal (orthogonal time-domain) of the two carriers (cos wt and sin wt) on