%1、 随机生成1000Hz的数据x
Fs = 1000;
t = linspace(0,1,Fs);
x = cos(2*pi*82*t)+0.5*randn(size(t)); %做模拟时将82改为round(rand*100)
% 2、建立5阶，截止频率128 Hz的滤波器，得到系数b、a
[b,a] = besself(10,128);
% 3、将模拟滤波器转换为数字滤波器,得到num、den
[num,den] = bilinear(b,a,128);
% 4、滤波
x_filtered = filter(num,den,x);
plot(x);hold on; plot(x_filtered,'r');legend('original signal','denoised signal')