xinhao1.m

应用matlab应用平台信号采集程序设计与整理。

%采样频率为1000Hz；
%数据长度为1024;
%信号生成
t=0:0.001:1.023;
for i=1:1024
    x(i)=8*sin(80*pi*t(i))+6*sin(200*pi*t(i))+sin(280*pi*t(i));
    if t(i)<=0.2
        s(i)=0;
    else
        s(i)=20*sin(2*pi*200*t(i)+pi/3).*exp(-20*(t(i)-0.2));
    end
end
x=x+s;
%graph signal x
figure(1);
plot(t,x);
xlabel('time/s');ylabel('amplitude/mv');title('signal x');
axis([0 1.023 -40 40]);
%3level 2^4=16, choose db wavelet package decomposition
wptree=wpdec(x,3,'db3');                             %wpdec function
plot(wptree);										   %wavelet package tree 
figure(3);
%section 1 to section 8 分解结果
for i=0:7
    subplot(4,2,i+1); section=wprcoef(wptree,[3 i]);
    plot(section);axis([0 1024 min(section) max(section)]);
    grid on;title(['section',num2str(i)]);   
end    
%Energy 每层的能量图谱
for i=1:3
    wptree=wpdec(x,i,'db3');   
    e=wenergy(wptree);
    figure(4);
    subplot(3,1,i);
    bar(e);
    axis([0 length(e) 0 150]);
    title(['第 ',num2str(i), ' 层']);
    for j=1:length(e)
        text(j-0.2,e(j)+20,num2str(e(j),'%2.2f'));
    end
end