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我在MATLAB以下代码:混乱在MATLAB滤波器滚降
L = 10000;
Power = -100;
A = 10^0.5;
Fs = 25e6;
fc1 = 100;
fc2 = 1e3;
fc3 = 10e3;
fc4 = 100e3;
fc5 = 1e6;
a1 = 2*pi*fc1/Fs;
a2 = 2*pi*fc2/Fs;
a3 = 2*pi*fc3/Fs;
a4 = 2*pi*fc4/Fs;
a5 = 2*pi*fc5/Fs;
x = wgn(1,L,Power);
y1 = zeros(1,L);
y2 = zeros(1,L);
y3 = zeros(1,L);
y4 = zeros(1,L);
y5 = zeros(1,L);
y = zeros(1,L);
for i = 2:L,
y1(i) = (1-a1)*y1(i-1) + a1*x(i);
y2(i) = (1-a2)*y2(i-1) + a2*x(i)/A;
y3(i) = (1-a2)*y3(i-1) + a3*x(i)/A^2;
y4(i) = (1-a2)*y4(i-1) + a4*x(i)/A^3;
y5(i) = (1-a2)*y5(i-1) + a5*x(i)/A^4;
y(i) = y1(i) + y2(i) + y3(i) + y4(i) + y5(i);
end
fft1 = fft(y);
fft1 = fft1(1:length(y)/2+1);
psd1 = (1/(Fs*length(y)))*abs(fft1).^2;
psd1(2:end-1) = 2*psd1(2:end-1);
freq = 0:Fs/length(y):Fs/2;
figure(3);
semilogx(freq,10*log10(psd1))
grid on
Ts = 40e-9;
z = tf('z',Ts);
H1 = a1/(1-(1-a1)*z^-1);
H2 = (a2/A)/(1-(1-a2)*z^-1);
H3 = (a3/A^2)/(1-(1-a3)*z^-1);
H4 = (a4/A^3)/(1-(1-a4)*z^-1);
H5 = (a5/A^4)/(1-(1-a5)*z^-1);
H = (H1 + H2 + H3 + H4 + H5);
figure(5);
bode(H),grid
该代码的意图是闪烁噪声,它有在它的功率谱密度斜率10dB的/癸建模。
若要建模,有一个过滤器的输出是y(i)
和输入x(i)
这是白色高斯噪声在这种情况下。在滤波器的波特图中(标记为图5),我可以看到它具有10dB/dec的滚降速度。
但是,当我检查输出噪声(在这种情况下y(i))功率谱密度(标记为图3)时,我看到20dB/dec的滚降。
有人能解释我做错了什么,为什么我无法获得10dB的功率谱密度滚降?
它看起来像这将有助于让你通过调试运行此。 – beaker