中文说明：此代码用于绘制接收器工作特性曲线，以便在主信号为实高斯信号且噪声为加性白实高斯信号时进行简单的能量检测。在这里，阈值是可用的
English Description：
This code is to plot receiver operating characteristic curve for simple energy detection, when the primary signal is real Gaussian signal and noise is addive white real Gaussian. Here, the threshold is available analytically.