短时Fourier

%信号自己写 即x
subplot(2,2,1),plot(x),xlabel('时间/s');
grid on;
X = fft(x);
subplot(2,2,2),plot([0:N-1/2]/N/dt,abs(X*2/N));
grid on;
xlabel('频率/Hz');ylabel('振幅')
Nw = 121;
nstep = 1;
h = window(@hamming,Nw);
Ts = [];
L = floor(Nw / 2);
F = [0:(Nw-1) / 2] / (Nw*dt);
TF = [];
for ii=1:nstep:N
    if(ii<L+1)
        xw = [zeros(1,L-ii+1),x(1:ii+L)].*h';
    elseif(ii>N-L)
        xw = [x(ii-L:N),zeros(1,(ii+L)-N)].*h';
    else
        xw = x(ii-L:ii+L).*h';
    end
    Ts = [Ts,ii];
    temp = fft(xw,Nw);
    TF = [TF,[temp(1:(Nw+1)/2)*2/Nw]'];
end
subplot(2,2,3),mesh(Ts,F,abs(TF));
xlabel('时间/s'),ylabel('频率/Hz'),zlabel('振幅')
subplot(2,2,4),pcolor(Ts,F,abs(TF));
shading interp;