FFT and HHT difference ???

[chill_vicky]

can anyone help me wats the difference between Hilbert-huang transform and FFT... i need the difference in their working... i got the following code in the same blog for FFT


Fs = 1000; % Sampling frequency
T = 1/Fs; % Sample time
L = 1000; % Length of signal
t = (0:L-1)*T; % Time vector
% Sum of a 50 Hz sinusoid and a 120 Hz sinusoid
x = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t)+ 1.2*sin(2*pi*200*t);
y = x + 2*t.*randn(size(t)); % Sinusoids plus noise
plot(Fs*t(1:50),y(1:50))
title('Signal Corrupted with Zero-Mean Random Noise')
xlabel('time (milliseconds)')
%%
NFFT = 2^nextpow2(L); % Next power of 2 from length of y
Y = fft(y,NFFT)/L;
f = Fs/2*linspace(0,1,NFFT/2);
% Plot single-sided amplitude spectrum.
figure,plot(f,2*abs(Y(1:NFFT/2)))
title('Single-Sided Amplitude Spectrum of y(t)')
xlabel('Frequency (Hz)')
ylabel('|Y(f)|')



according to this it seperates the freq components in a given mixed signal and represents it as a single sided spectrum... In case of HHT with the Intrinsic Mode Function we get the same output... so wat is the major difference between the two (FFT and HHT)... the striking difference???!!!????


pls anyone help me out in this...