I was playing with the Interpolating FIR Filter Block and noticed that the mentioned filter delays tags not properly. What I mean is that when the interpolation factor is different than 1, then the filter delays the tags by the Sample Delay * Interpolation factor value. In my opinion this is not correct behavior. Group delay of the filter is constant and the interpolation factor shouldn't affect the process of delaying the tags. Below, I am attaching the plot and GRC flowgraph which demonstrate the problem and where you can see the observed behavior.
Number of the taps in RRC filter used in the simulation: 41
Group delay: 20
Actual group delay: 40
What do you think?
