Frequency Guided Generalized Adaptive Notch Filtering—Tracking Analysis and Optimization

摘要

Generalized adaptive notch filters (GANFs) are estimators of coefficients of quasi-periodically time-varying systems, encountered e.g., in RF applications when Doppler effect takes place. Current state of the art GANFs can deliver highly accurate estimates of system variations’ frequency, but underperform in terms of accuracy of system coefficient estimates. The paper proposes a novel multistage GANF with improved coefficient tracking properties and smaller sensitivity to choice of estimation gains. The processing pipeline consists of three stages. First, a pilot filter computes preliminary frequency estimates. Second, a special linear filter reshapes the pilot frequency estimates. Third, a frequency guided GANF works out final estimates of system coefficients. A nontrivial design of the second stage filter assures that the proposed solution has a considerably better performance than current stage of the art solutions or a simpler two-stage approach consisting of the pilot and the frequency guided filter only.