How to perform frequency convolution?

1. What is the frequency convolution theorem?
2. How do you use convolution to calculate FFT?

What is the frequency convolution theorem?

Statement - The frequency convolution theorem states that the multiplication of two signals in time domain is equivalent to the convolution of their spectra in the frequency domain.

How do you use convolution to calculate FFT?

FFT convolution uses the principle that multiplication in the frequency domain corresponds to convolution in the time domain. The input signal is transformed into the frequency domain using the DFT, multiplied by the frequency response of the filter, and then transformed back into the time domain using the Inverse DFT.