基于MATLAB的FIR数字滤波器设计

MATLAB Design of FIR Digital Filter

针对数字信号处理里面的有限长单位脉冲响应(FIR)数字滤波器的设计方法进行讨论,描述4类线性相位FIR数字滤波器的幅度特性和相位特性.分析了应用MATLAB分别采用窗化法和频率采样法设计具有线性相位特性的FIR数字滤波器的设计过程和设计特点.窗化法的优点是设计简单,可以设计任意频率特性的滤波器,但窗化法设计滤波器时通带和阻带的边界频率不易控制,滤波器的长度也需要多次设计才能得到满意的结果.频率采样法进行FIR数字滤波器设计的优点是直接从频域设计,物理概念清楚,直观方便,特别适合于频率响应只有较少非零取样值的窄带滤波器.

The design of finite unit impulse response （ FIR） filter in digital signal processing has beendiscussed. Amplitude and phase characteristics of linear-phase FIR filter have been described. Design proceduresand characteristics of window method and frequency sampling method for designing linear-phase FIR filter inMATLAB have been analyzed. The advantage of the window method is that the design is simple and the filter can bedesigned for any frequency characteristic. But the boundary frequency of the passband and stopband is not easilycontrolled when the filter is designed by the window method, and the length of the filter needs to be designed manytimes to get a satisfactory result. The advantage of frequency sampling method in designing FIR digital filter is thatit is designed directly from the frequency domain, and its physical concept is intuitive. The frequency samplingmethod is especially suitable for narrow-band filters with only a few nonzero sampling values.