# FFT spectre graph measurements y-axis

I am very new to this things. Sorry for probably stupid question. I don't understand what units and meaning have the values on Y-axis of Fourier Transform graph? On X-axis it is Frequency (Hz). Pretty clear. Can't find the meaning of Y.

Here is the code in MATLAB I used to produce the graph, and the image of the output:

A = 5;
t = 0:1/1000:1;
f1 = 7;
s = A * sin(2 * pi * fi * t);
F = fft(s);
figure;
plot(abs(F)), (s);


• Are we talking about the discrete Fourier transform (DFT) or the continous Fourier transform? Note that the unit of the x-axis of the DFT (or FFT) is not Hz, it's the normalized frequency. – Deve Nov 7 '12 at 9:58