2
$\begingroup$

I am measuring acoustic emission signals. The a.e. frequency range is 20kHz to 1 MHz. The sampling frequency that I,set was 100kHz Samples per second. I must be able to detect a maximum of 50 kHz signal using it. But when I do fft I get a maximum of only 300Hz.

Can anyone tell me where I would have gone wrong?

$\endgroup$
  • 5
    $\begingroup$ Could you please use scientific/powers of 10 notation for your frequencies, life is too short to waste it counting zeros in numbers. $\endgroup$ – Conrad Turner Feb 15 '15 at 9:15
  • 2
    $\begingroup$ or units MHz and kHz, or grouping $\endgroup$ – Olli Niemitalo Apr 16 '15 at 12:09
1
$\begingroup$

How are you determining your maximum frequency?

If you sample at $f_s$ the frequency resolution (the frequency difference between frequency components) of your FFT is $f_s/N$, where $N$ is the number of samples collected. And the maximum resolvable frequency is the Nyquist frequency corresponding to the sample rate. For more information see here

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.