The frequency cutoff (fc) can be dynamically (i.e., actively) set according to the estimated rotational speed (ω) of the rotor 103. Based on the estimated rotational speed (ω) described above, the cutoff frequency (fc) can be calculated, e.g., by the controller 106, as:

$\begin{array}{cc}{f}_c=\frac{\omega }{2?\pi }& \mathrm{eq}.?3\end{array}$

Accordingly, the downstream low pass filter 118 generates a filtered AC bandwidth signal (BW_FILTERED) shown in FIG. 5, which removes the remaining harmonics previously found in the initial bandwidth signal (see FIG. 4).