Lowering Spectral Resolution of FFT

1. How do I change the resolution on my FFT?
2. How can spectral leakage be reduced?
3. How does FFT length affect the spectrum?
4. How do you prevent spectral leakage in FFT?

How do I change the resolution on my FFT?

The most intuitive way to increase the frequency resolution of an FFT is to increase the size while keeping the sampling frequency constant. Doing this will increase the number of frequency bins that are created, decreasing the frequency difference between each.

How can spectral leakage be reduced?

We have seen that spectral leakage is reduced by tapering the digital signal by a window function before the DFT takes place. A generalization of this technique is the short-time discrete Fourier transform (STDFT).

How does FFT length affect the spectrum?

The selected FFT size directly affects the resolution of the resulting spectra. The number of spectral lines is always 1/2 of the selected FFT size. Thus a 1024 point FFT produces 512 output spectral lines. The frequency resolution of each spectral line is equal to the Sampling Rate divided by the FFT size.

How do you prevent spectral leakage in FFT?

By increasing the side lobe roll-off rate, you can reduce spectral leakage. Selecting a window function is not a simple task. Each window function has its own characteristics and suitability for different applications. To choose a window function, you must estimate the frequency content of the signal.