Group Delay
grpdelay(filter, N)—Calculates the group delay, the phase change of the input signal envelope, imposed by a filter.
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.
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