Weight-Function Notch Filter Algorithm for Narrow-band Interference in eLORAN System

In order to solve the problem of in-band interference of enhanced LOng RAnge Navigation (eLORAN) system, an adaptive Weight-Function Notch Filter (WF-NF) algorithm is proposed based on the principle of Notch Filter (NF) to resist narrow-band interference. Firstly, the applicability of NF algorithm in eLORAN system and the pseudo convergence caused by detection frequency difference are analyzed. Then, by adding the weight function of frequency difference, a new WF-NF algorithm is derived to solve the notch logic flaw caused by the inherent frequency difference. Next, a gradient-jump optimization technique is designed to improve the convergence speed of weight coefficients. Finally, the stability, multiple applicability and practicability of the new algorithm are verified by simulation experiments in various environments. The analysis results show that the WF-NF algorithm can overcome the practical problem of detection frequency difference, realize efficient interference tracking and filtering, and compensate the accuracy of interference detection, so as to provide guarantee for the subsequent signal processing process.