Tracking and Mitigation of Chirp-Type Interference in GPS Receivers Using Adaptive Notch Filters

A Global Positioning System (GPS) receiver is extremely prone to intentional and unintentional interference due to weak signal power experienced on the surface of the earth, which severely affects the navigation functionality and occasionally avoids the receivers from acquiring the GPS signal. This work presents a comparative performance analysis of two different types of Adaptive Notch Filtering (ANF) algorithms for GPS specific applications that are (1) Direct form 2nd Order ANF and (2) Lattice-based ANF for tracking and mitigation of Chirp-type Interference. Three classes of chirp-type interference signals, studied in this paper, are linear chirp, quadratic chirp and cubic chirp. Performance of each ANF algorithm is evaluated at the output of the acquisition module in terms of search-grid SNR and Peak metric.