Stone Studio

“Linear Phase” refers to the condition where the phase response of the filter is a linear (straight-line) function of frequency (excluding phase wraps at +/- 180 degrees). This results in the delay through the filter being the same at all frequencies. Therefore, the filter does not cause “phase distortion” or “delay distortion”. The lack of phase/delay distortion can be a critical advantage of FIR filters over IIR and analog filters in certain systems, for example, in digital data modems [1]. Another application where a constant groupd delay filter is used when filtering music signals or video signals [2].

Links

[1]: FIR Filter FAQ from DSPGuru

[2]: DSP 5C: Digital Signal Processing – Prof E. Ambikairajah

[3]: A live webcast is available at UC Berkeley, by Avideh Zakhor: Linear Phase Filtering. The handout is available here