说明：  QAM调制解调的全过程，包括产生随机码，映射调制，加载波，进入信道，解调和判决，过程比较详细，其他调制方式也可以借鉴
(QAM modulation and demodulation process, including the generated random code, mapping modulation, plus carrier, into the channel, demodulation and sentencing, the process in more detail, other modulation can also learn)