用Hanning窗设计线性相位滤波器，绘制幅频和相位特性曲线，并在改变N的值后观察N对滤波器特性的影响及其时域特点。-Hanning window with a linear phase filter design, drawing amplitude frequency and phase characteristic curve, and change the value of N, N were observed on the filter characteristics and time domain characteristics.