在仿真实验中要产生具有某个信噪比的混合信号样本zt。 这时，先求出不含噪声的有用信号的幅度(最大值)am 再根据给定的信噪比snr(db)反推噪声电平theta。以高斯噪声为例-In the simulation experiments to produce with a signal-to-noise ratio of zt mixed signal sample.at this moment, to take the first without noise and useful