FDATool设计FIR低通滤波器

本文主要是介绍FDATool设计FIR低通滤波器，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

（一）设计一个低通滤波器

采样频率 Fs = 50Hz Fpass = 10Hz Fstop = 20Hz

打开matlab，键入fdatool后，会弹出该工具的对话框。然后按照下图设置相关参数，参数列表中的Fs应该是采样频率，Fc是截止频率，即幅频特性曲线-3dB对应的频率。点击“Design Filter”后，幅频特性曲线会被更新。

Targets -> generate C Header 生成的头文件

/** Filter Coefficients (C Source) generated by the Filter Design and Analysis Tool* Generated by MATLAB(R) 9.0 and the Signal Processing Toolbox 7.2.* Generated on: 26-Dec-2018 09:54:34*//** Discrete-Time FIR Filter (real)* -------------------------------* Filter Structure  : Direct-Form FIR* Filter Length     : 6* Stable            : Yes* Linear Phase      : Yes (Type 2)*//* General type conversion for MATLAB generated C-code  */
#include "tmwtypes.h"
/* * Expected path to tmwtypes.h * C:\Program Files\MATLAB\R2016a\extern\include\tmwtypes.h */
const int BL = 6;
const real64_T B[6] = {-0.08631845386171,   0.0581511407323,   0.5053647362323,   0.5053647362323,0.0581511407323, -0.08631845386171
};   //Fir 滤波器参数

（二）Matlab 脚本测试

clear all;Ts = 0.02;      %采样时间   
%FDAtool设计的参数  Target -> generate C header 
b = [ -0.08631845386171    0.0581511407323    0.5053647362323    0.5053647362323  0.0581511407323  -0.08631845386171];  %滤波器参数
ss = [0 0 0 0 0 0];
for i = 1:1:100time(i) = i * Ts;x(i) = 2*sin(10 * pi * time(i)) + cos(40 * pi * time(i)) + 0.1 * rands(1);        %5Hz 20Hz 原信号%代数方法求滤波后的波形ss(6) = ss(5);ss(5) = ss(4); ss(4) = ss(3);ss(3) = ss(2);ss(2) = ss(1);ss(1) = x(i);zz(i) = b(1) * ss(1) +  b(2) * ss(2) +  b(3) * ss(3) +  b(4) * ss(4) +  b(5) * ss(5) +  b(6) * ss(6);
endyy = filter(b,1,x);         %使用 filter 函数执行滤波器
figure(1);
plot(time,x,'b',time,yy,'r',time,zz,'y+');
xlabel('秒');%% 傅里叶变换，左半,检查滤波效果
figure(2)
fy = fft(x);
fyy = fft(yy);
fzz = fft(zz);
i=1:1:100;
plot(i,abs(fy),'y',i,abs(fyy),'g+',i,abs(fzz),'r-');
xlabel('1/2 Hz');
ylabel('幅度乘以采样频率')

（三）仿真结果