Frequency estimation of harmonic signals subject to step-wise variations using notch filters and funnel filters

Funnel filters are a recently proposed class of filters, which are useful in the field of adaptive control and signal processing, for the identification of the instantaneous frequency of time-varying harmonic signals. Such filters have been claimed to outperform standard notch filters, when the frequency to be estimated is subject to step-wise changes. A numerical procedure for the evaluation of the tracking performances of notch and funnel filters is proposed, and a comparative analysis is presented.