Group Delay
• grpdelay(filter, N)—Calculates the group delay, the phase change of the input signal envelope, imposed by a filter.
Arguments
• filter is a complex-valued matrix of filter coefficients in cascade form.
• N is an integer number of frequencies at which to evaluate group delay.
Additional Information
• The function returns a vector of length 2N containing the group delay at each frequency.
• The algorithm uses the Fourier transform of an FIR-only filter that gives the same group delay as the original filter, with new coefficients c[n].
• Group delay is given by Re[ j (1/C) dC/dw].
• Group delay is one measure of the filter's impact on the phase of the input signal.