Cascading IIR filter with All pass filter (APF) for constant group delay and linear phase over the passband using MATLAB not working?

1. Which filter should one use to get a constant group delay?
2. How to calculate group delay in Matlab?
3. What is group delay of IIR filter?
4. What is fir1 in Matlab?

Which filter should one use to get a constant group delay?

By far the most common applications for FIR filters are linear phase FIR filters because of the benefit of constant group delay which is the result of linear phase.

How to calculate group delay in Matlab?

The group delay is evaluated at 8192 points equally spaced around the upper half of the unit circle. [ gd , w ] = grpdelay( sysobj , n ) returns the group delay of the filter System object and the corresponding frequencies at n points equally spaced around the upper half of the unit circle.

What is group delay of IIR filter?

The so-called “group delay” is simply the time lag between the envelope of input burst and the envelope of the amplitude of the output burst. So, group delay means a propagation delay through a filter, measured on the envelope of the signal.

What is fir1 in Matlab?

b = fir1( n , Wn ) uses a Hamming window to design an n th-order lowpass, bandpass, or multiband FIR filter with linear phase. The filter type depends on the number of elements of Wn .