A Novel Real-Time Convergence Evaluation Index of an Adaptive Notch Filter

This paper proposes an evaluation index (EI) for the frequency estimation accuracy of an adaptive notch filter (ANF). Conventional indices are useful for evaluating the convergence performance of ANFs in simulations and experiments; however, they require the true wideband or narrowband components and therefore cannot be computed in practical online operation. In contrast, the proposed EI is calculated in real time using only signals available inside the ANF. Because the EI is normalized, it can be used as a feedback signal for adaptive algorithms.