PGRPDELAY Group delay of a filter with periodic boundaries
Usage: ggd = pgrpdelay(g,L);
PGRPDELAY(g,L) computes group delay of filter g as a negative
derivative of the phase frequency response of filter g assuming
periodic (cyclic) boundaries i.e. the delay may be a negative number.
The derivative is calculated using the second order centered difference
approximation.
The resulting group delay is in samples.
Example:
--------
The following example shows a group delay of causal, moving average
6tap FIR filter and it's magnitude frequency response for comparison.
The dips in the group delay correspond to places where modulus of the
frequency response falls to zero.:
g = struct(struct('h',ones(6,1),'offset',0));
L = 512;
figure(1);
subplot(2,1,1);
plot(-L/2+1:L/2,fftshift(pgrpdelay(g,512)));
axis tight;ylim([0,4]);
subplot(2,1,2);
magresp(g,L,'nf');
Package: ltfat