说明：  对QPSK解调系统完美建模，其中通过改变码元速率和载波频率，再计算相应的环路滤波器的参数，即可实现多种QPSK模型的解调，且该模型可通过SYSTEM generator进行量化，从而生成ISE能直接使用的HDL代码。 matlab版本：2007a
(Perfect for QPSK demodulation system modeling, which by changing the symbol rate and carrier frequency, and then calculate the corresponding parameters of the loop filter, QPSK demodulator can achieve a variety of models, and the model can be quantified by SYSTEM generator thereby generating ISE HDL code can be used directly. matlab version: 2007a)