Husheng Li, UTK-EECS, Fall 2012
The specification of filter is usually given by the tolerance scheme. Discrete Fourier Transform (DFT) has both discrete time and discrete frequency. DTFT has a continuous frequency, which is difficult to process using digital processors. DFT has a fast computation algorithm: FFT.
The sequence having DFS equaling the frequency domain sampling results from the aperiodic sampling.
Since there is a fast computation algorithm in DFT, we can compute convolution via DFT: Compute the DFTs of both sequences Compute the product of both DFTs. Compute the output using IDFT. The length of DFT should be properly chosen; otherwise we will see aliasing.