### A.3 SNR in second-order pole regime

Substituting Eqs. (528) and (527) into Eq. (526), we obtain that
where
If (the sub-optimal case), then
The maximum of (556) in corresponds to
and is equal to
In both cases (558) and (560), we should minimize the expression
in . It is easy to see that the optimal is equal to
which gives the SNR (530) for the optimal case (529) and (531) – for the sub-optimal one
.