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When do you apply zero padding to FFT?
One final thought on zero padding the FFT: If you apply a windowing function to your waveform, the windowing function needs to be applied before zero padding the data. This ensures that your real waveform data starts and ends at zero, which is the point of most windowing functions.
Is it a bad idea to zero bins in FFT?
If a time-domain filter that can output all those ripples (ringing) is a “bad idea”, then so is zeroing bins. These ripples will be largest for any spectral content that is “between bins” or non-integer-periodic in the FFT aperture width.
Why does FFT have a poor time resolution?
FFT gives poor time resolution i.e it doesn’t give information at what time that particular frequency exist. It gives information on existing frequency components for given signal duration. By zeroing bins in FFT gives poor resolution after IFFT in time domain. Thanks for contributing an answer to Signal Processing Stack Exchange!
How is the sampling frequency of FFT calculated?
1 Answer 1. The FFT output will be bins evenly spaced from DC (bin 0) to 1 bin less than your sampling frequency. Thus your sampling frequency is at N for bins 0 to N-1, where N is the number of samples in your time domain sequence.
When to use zero padding before or after window?
Zero padding before the window doubles the frequency resolution to 1 Hz, and thus reduces the picket fence, but now the leakge has returned. The best procedure is to window first, then zero pad.
Why do you zero pad a signal before DFT?
In general zero-padding prior to DFT is equivalent to interpolation, or sampling more often, in the transformed domain. Here is a quick visualization of how the opposite works. If you sample a bandlimited signal in time at higher rate, you get a more ‘squashed’ spectrum, i.e. a spectrum with more zeros at both ends.
What happens when you add a window to a FFT?
When taken with a 2 Hz resolution FFT and no window, there is significant leakage and picket fence effect. Adding a window reduces the leakage, but not the picket fence effect. Zero padding before the window doubles the frequency resolution to 1 Hz, and thus reduces the picket fence, but now the leakge has returned.