Zeroing bins before IFFT

1. Why is it a bad idea to filter by zeroing out FFT bins?
2. Why zero padding is needed in FFT?
3. Does zero padding affect FFT?
4. What is the effect of zero padding?

Why is it a bad idea to filter by zeroing out FFT bins?

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.

Why zero padding is needed in FFT?

In addition to making the total number of samples a power of two so that faster computation is made possible by using the fast Fourier transform (FFT), zero padding can lead to an interpolated FFT result, which can produce a higher display resolution.

Does zero padding affect FFT?

Zero padding allows one to use a longer FFT, which will produce a longer FFT result vector. A longer FFT result has more frequency bins that are more closely spaced in frequency.

What is the effect of zero padding?

Zero padding enables you to obtain more accurate amplitude estimates of resolvable signal components. On the other hand, zero padding does not improve the spectral (frequency) resolution of the DFT. The resolution is determined by the number of samples and the sample rate.