separating a part of plot from an original fft plot

i have a fft plot of an audio file over the range 0 to 3000hz. now i want to separate the 1000 to 2000 hz part of the plot into a diff variable. how to do that...?????

thanks in advance

Answer 1

[Tom]

you can use the greater than/ less than symbols to do this: say your frequency data is stored as X, and your FFT data is stored as Y.

Z=Y(X>=1000 & X<=2000)

[777]

i had that in mind but the problem here is that fft is stored in a variable which is i dont think a function of frequency.

[Dr. Seis]

If the the number of data points (N) is even, then:

Fs = 6000;

Nyquist = Fs/2; % i.e., 3000 Hz

df = Fs/N;

X = ifftshift(-Nyquist:df:Nyquist-df);

if N is odd:

X = [(0:df:Nyquist) -1*sort(df:df:Nyquist,'descend')]