matlab仿真程序，产生QPSK调制的信号，严格按照QPSK的调制步骤分I路Q路产生信号，最后两路相加，产生已调信号，调制信号随机产生，载波信号是余弦信号。-matlab simulation program to produce the QPSK modulation signal, in strict accordance with the QPSK modulation of the sub-step road Q road I have a signal, the sum of the last two, have been transferred signal, randomly generated modulated signal, carrier signal is a cosine signal.