success.m

这是一个对信号和噪声进行分析的程序

b=0.15;
a=15;
f=14.65;
h=pi/2;
s=zeros(1,100);
y1=zeros(1,100);
y=zeros(1,100);
n=1;
tf=100;
for t=0.01:0.01:1
if t>b
s(n)=sin(2*pi*f*t+h)*exp(-a*(t-b));
else
    s(n)=0;
end
y1(n)=2*sin(2*pi*t+pi/8);
n=n+1;
end
y=20*s+y1;
t1=0.01:0.01:1;
y2 = awgn(y,10,'measured'); % Add white Gaussian noise. 
plot(t1,y,t1,y2) % Plot both signals. 
legend('Original signal','Signal with AWGN');
Y=fft(y2);
figure(1)
plot(t1,s)
figure(2)
plot(t1,y)
figure(3)
plot(t1,y2)
F=Y(1:n/2+1); % F(k)=Y(k)(k=1:N/2+1)
tf=tf*(0:n/2)/n;

figure(4)% 使频率轴f从零开始
plot(tf,abs(F))            % 绘制振幅-频率图
xlabel('Frequency')
ylabel('|F(k)|')
Nw=4;   %窗宽
L=Nw/2;   %L=10%

Tn=(n-Nw)/L+1; %Tn=9  窗的移动次数 
nfft=32;  
TF=zeros(Tn,nfft);
fs=100;
Ts=1/fs;
yw=zeros(1,Nw);
for i=1:Tn
    yw=y2((i-1)*L+1:i*L+L)
 
  temp=fft(yw,nfft);
    temp=fftshift(temp);
    TF(i,:)=temp;
end 
 figure(5)
fnew=((1:nfft)-nfft/2)*fs/nfft;
tnew=(1:Tn)*L*Ts;

[F,T]=meshgrid(fnew,tnew);
mesh(F,T,abs(TF))
Y2=fft(y3);
F2=Y2(1:n/2+1);