What is Group delay?
A quantity that describes how much each frequency component of a signal passing through a filter is delayed, defined as the negative derivative of the phase response φ(ω) with respect to frequency (−dφ/dω). If the group delay is the same at all frequencies, the whole waveform is simply delayed with its shape intact. An N-tap FIR filter with symmetric coefficients has a constant group delay of (N − 1)/2 samples. In IIR and analog filters the group delay varies with frequency and often peaks near the cutoff frequency, distorting pulse shapes. Bessel filters are designed for a flat group delay.
Japanese name: 群遅延
Group delay appears in 2 practice questions across 2 topics, including Digital Signal Processing Basics, Analog and electronic circuits.