work2.m

此程序为用matlab实现信号特征提取的实验程序

dt=0.001;
t1=-5.0005:dt:5.0005;
t2=t1;
fw1=2;
fw2=9;
x2t=(1.2+cos(0.2*2*pi*t1));
x1tRE=x2t.*sin(10*2*pi*t1+sin(2*pi*t1));
ht=1./(pi*t2);
%生成解析信号
[f0,t]=ctsconv1(x1tRE,ht,t1,t2,dt);

for k=5001:15002
    x1tIM(k-5000)=f0(k);
end
x1t=x1tRE+j*x1tIM;
x1t_abs=abs(x1t);
%画出原信号
subplot(311)
plot(t1,x1tRE);grid on;
axis([min(t1),max(t1),min(x1tRE)-abs(min(x1tRE)*0.2),max(x1tRE)+abs(max(x1tRE)*0.2)])
title('x1(t)');xlabel('t')
%画出x2t
subplot(312)
plot(t1,x2t);grid on;
axis([min(t1),max(t1),min(x2t)-abs(min(x2t)*0.2),max(x2t)+abs(max(x2t)*0.2)])
title('x2(t)');xlabel('t')
%画出x1tRE的包络
subplot(313)
plot(t1,x1t_abs),grid on;axis([min(t1),max(t1),min(x1t_abs)-0.2,max(x1t_abs)+0.2]);xlabel('t');title('xt的包络');
%画出检出包络与理论值的差
plot(t1,(x1t_abs-x2t)),grid on;axis([min(t1),max(t1),min(x1t_abs)-0.2,max(x1t_abs)+0.2]);xlabel('t');title('xt的包络');
%求x1t的相位及瞬时频率并画图
x1t_phi=angle(x1t);
figure;
subplot(211);plot(t1,x1tRE);grid on;axis([min(t1),max(t1),min(x1tRE)-0.2,max(x1tRE)+0.2]);xlabel('t'),ylabel('xt');title('实信号xt')
subplot(212);plot(t1,x1t_phi);grid on;axis([min(t1),max(t1),min(x1t_phi)-0.2,max(x1t_phi)+0.2]);xlabel('t'),ylabel('phi');title('xt的相位')
%用微分法求x1t的瞬时频率
for m=1:10001
    x1t_freq(m)=(x1t_phi(m+1)-x1t_phi(m))/(dt*2*pi);
end
x1t_freq(10002)=x1t_freq(10001);
%打开新窗口，画x1t及其瞬时频率
figure;
subplot(211);plot(t1,x1tRE);grid on;axis([min(t1),max(t1),min(x1tRE)-0.2,max(x1tRE)+0.2]);xlabel('t'),ylabel('xt');title('实信号xt')
subplot(212);plot(t1,x1t_freq);grid on;axis([min(t1),max(t1),-2,30]);xlabel('t'),ylabel('frequency');title('xt的瞬时频率')