FINDING FREQUENCY FROM FFT PLOT

my fft plot looks like above.how to find lower and higher frequencies for the above curve so that the bandwidth(upper-lower frequency) can also be calculated .i need to display lower and upper frequencies also.

Answer 1

[Hiro Yoshino]

Try this?:

% P fft power
% F fft frequency
idx = (P == PowerThreshold); % detect the indices of the power that match the threshold.

% Here are what you want I guess:
F_low = F(idx);
F_low = F_low(1);
F_high = F(idx);
F_high = F_high(end);

The point is extracting indices that correspond your threshold of the power.