FIR函数通过定义的系数和延时线来实现有限脉冲响应FIR滤波器。该函数产生了对输入数据的响应。该过滤器（通带，阻带等特点）由系数和抽头数决定。-FIR function by defining the coefficients and delay line to achieve the finite impulse response FIR filter. The function of the input data generated response. The filter (passban

使用脉冲响应不变法设计巴特沃斯低通滤波器。-Using the impulse response is not political reform design butterworth low-pass filter.