Robust GPS Carrier Tracking Algorithms During Strong Equatorial Scintillation for Dynamic Platforms

Abstract

This paper presents two adaptive carrier tracking algorithms to process strong equatorial scintillation signals received on a dynamic platform. One is an adaptive-bandwidth phase lock loop (AB-PLL), and the other is based on a generalized adaptive Kalman filter (AKF) framework. A recently developed physic-based scintillation simulator is used to generate realistic equatorial scintillation signals observed on dynamic platforms to evaluate the two algorithms. Three typical aircraft trajectories are simulated to emulate three scenarios of scintillation signals with fast, moderate, and slow temporal structures. A conventional PLL is implemented to access the performances of fixed-value tracking loop parameters such as integration time and bandwidth. Based on the assessment results, the bandwidth values for the AB-PLL under different fading levels are determined. The AKF algorithm applies the receiver oscillator noise modeling approach to model the phase scintillation effects. This is achieved by deriving scintillation-equivalent h parameters using Allen variance method for simulated phase scintillation. Evaluations of the AB-PLL and AKF using the simulated scintillation data on dynamic platforms showed robust performances of both algorithms.