设计一个简易数字信号传输性能分析仪，实现数字信号传输性能测试；同时，设计三个低通滤波器和一个伪随机信号发生器用来模拟传输信道。(A simple digital signal transmission performance analyzer is designed to test the transmission performance of the digital signal. At the same time, three low-pass filters and a pseudo-ra