I have produced this spectrum using this matlab code:
signal= wavread('/Users/ecabuk/Downloads/DR0000_0165.wav'); X_mags = abs(fft(signal)); bin_vals = [0 : N-1]; fax_Hz = bin_vals*fs/N; N_2 = ceil(N/2); plot(fax_Hz(1:N_2), 10*log10(X_mags(1:N_2))) xlabel('Frequency (Hz)') ylabel('Magnitude (dB)'); title('Single-sided Magnitude spectrum (Hertz)'); axis tight
It has two clear picks near at ~24KHz and ~25KHz.
How can I crop 24KHz and then return to time domain and save as a wave file, so I can hear that. (and same thing for 25KHz of course)
I am not sure but am I trying to make a Demodulation process?