Question

Which of the following are required to minimize the value of ε?

(a) rhh(l)

(b) rdh(l)

(c) d(n)

(d) all of the mentioned

This question was posed to me in an international level competition.

My question comes from FIR Least Squares Inverse Filters in section Digital Filters Design of Digital Signal Processing

Answer 1

The correct answer is (d) all of the mentioned

Best explanation: When ε is minimized with respect to the filter coefficients, we obtain the set of linear equations

\(\sum_{k=0}^M b_k r_{hh}(k-l)=r_{dh} (l)\), l=0,1,…M

and we know that rdh(l) depends on the desired output d(n).