%裝載數(shù)據(jù)
load seat.dat -ascii
dt=0.005;
N=length(seat);
subplot(2,1,1);
plot((1:N)*dt,seat);
xlabel('時(shí)間 t / s');
ylabel('座椅質(zhì)心響應(yīng)');

nfft=1024;
y=abs(fft(seat,nfft));
fs=1/dt;
subplot(2,1,2);
plot((0:nfft/2-1)/nfft*fs,y(1:nfft/2));
xlabel('頻率 f / Hz');
ylabel('功率譜 / W');

%d5小波進(jìn)行4層分解
%一維小波分解
[c,l] = wavedec(seat,4,'db5');
%重構(gòu)第1-4層細(xì)節(jié)系數(shù)
d4 = wrcoef('d',c,l,'db5',4);
d3 = wrcoef('d',c,l,'db5',3);
d2 = wrcoef('d',c,l,'db5',2);
d1 = wrcoef('d',c,l,'db5',1);

%顯示細(xì)節(jié)號(hào)
figure(2);
subplot(4,1,1);
plot(d1,'LineWidth',2);
ylabel('d1');
subplot(4,1,2);
plot(d2,'LineWidth',2);
ylabel('d2');
subplot(4,1,3);
plot(d3,'LineWidth',2);
ylabel('d3');
subplot(4,1,4);
plot(d4,'LineWidth',2);
ylabel('d4');
xlabel('樣本序號(hào) n');