213cy
commented
9 years ago 
Open 213cy opened 9 years ago
213cy
commented
9 years ago
213cy
commented
9 years ago Fs = 1000; % Sampling Frequency
%%
t = 0:1/Fs:2;
y = chirp(t,0,1,100);
ax(1)=subplot(421);
plot(y)
axis tight
subplot(422)
spectrogram(y,256,192,256,Fs,'yaxis');
ylim([0,250])
%% IIR elliptic filter
Rp = 1;
Rs = 20;
Wp = 80;
Ws = 120;
[n,Wp_n] = ellipord(2_Wp/Fs,2_Ws/Fs,Rp,Rs);
[b,a] = ellip(n,Rp,Rs,Wp_n);
%
y_IIR=filter(b,a,y);
ax(2)=subplot(423);
plot(y_IIR)
axis tight
subplot(424)
spectrogram(y_IIR,256,192,256,Fs,'yaxis');
ylim([0,250])
%% FIR hann win filter(Signal Processing Toolbox function)
% 40 决定的 hann
n2=round((4_Fs/Wp-1)/2);
b2=fir1(n2-1,2_Wp/Fs,hann(n2));
y_hann=filter(b2,1,y);
ax(3)=subplot(425);
plot(y_hann)
axis tight
subplot(426)
spectrogram(y_hann,256,192,256,Fs,'yaxis');
ylim([0,250])
%% FIR kaiser win filter(DSP Toolbox function)
Fpass = 80; % Passband Frequency
Fstop = 120; % Stopband Frequency
Apass = 1; % Passband Ripple (dB)
Astop = 20; % Stopband Attenuation (dB)
% Construct an FDESIGN object and call its design method.
h = fdesign.lowpass(Fpass, Fstop, Apass, Astop, Fs);
%set(h);
get(h);
designmethods(h);
Hd = design(h,'kaiserwin');
%
y_kaiser=filter(Hd,y);
ax(4)=subplot(427);
plot(y_kaiser)
axis tight
subplot(428)
spectrogram(y_kaiser,256,192,256,Fs,'yaxis');
ylim([0,250])
%%
linkaxes(ax)
%%
fvtool(b,a,b2,1,Hd.Numerator,1)
legend('elliptic','hann','kaiser')