可以实现正余弦，方波相关滤波功能，并可以观察原理误差，测量恒带宽特性，研究低通滤波器与带宽的关系，是一个综合性模拟实验平台-Can achieve positive cosine, square wave correlation filter function, and can observe the principle error, measured bandwidth characteristics constant, low-pass filter with the bandwidth o