Design and Validation of a Cascading Vector Tracking Loop in High Dynamic Environments

Abstract

This paper designs a cascading vector tracking loop based on the Unscented Kalman Filter (UKF) for high dynamic environment. Constant improvement in dynamic performance is an enormous challenge to the traditional receiver. Due to the doppler effect, the satellite signals received by these vehicles contain fast changing doppler frequency shifts and the first and second derivatives of doppler frequency, which will directly cause a negative impact on the receiver’s stable tracking of the signals. In order to guarantee the dynamic performance and the tracking accuracy, this paper designs a vector carrier structure to estimate the doppler component of a signal. Firstly, after the coherence integral, the IQ values are reorganized into new observations. Secondly, the phase error and frequency of the carrier are estimated through the pre-filter. Then, the pseudorange and carrier frequency are used as the observations of the main filter to estimate the motion state of the aircraft. Finally, the current state is fed back to the carrier Numerical Controlled Oscillator (NCO) as a complete closed loop. In the whole structure, the cascading vector loop replaces the original carrier tracking loop, and the stable signal tracking of code loop is guaranteed by carrier assisted pseudo-code method. In this paper, with the high dynamic signals generated by the GNSS signal simulator, this designed algorithm is validated by a software receiver. The results show that this loop has a wider dynamic tracking range and lower tracking error than the second-order frequency locked loop assisted third-order phase locked loop in high dynamic circumstances. When the acceleration of carrier is 100 g, the convergence time of vector structure is about 100 ms, and the carrier phase error is lower than 0.6 mm.

A MCKF-based cascade vector tracking method designed for ship navigation

“…The code tracking performance of the vector tracking loop (VTL) has been improved to varying degrees. However, the PLL and FLL are more likely to lose lock than the VDLL [8]. Carrier phase tracking has a positive effect on the reliability, availability, and accuracy of receivers [4].…”

Enhancing USVs navigation based on minimum error entropy of GPS vector tracking

“…This method aims to enhance the robustness and accuracy of GNSS receivers, particularly when partial satellite interruption occurs [27]. The VTL in [28,29] was improved by applying the unscented Kalman filter, which aims to enhance the measurement accuracy of the tracking loop during high-dynamic motions. Cheng et al implemented the adaptive strong tracking Kalman filter on carrier tracking with the objective of enhancing the tracking performance of GNSS receivers in GNSS-challenged environments [30].…”

Performance Enhancement and Evaluation of a Vector Tracking Receiver Using Adaptive Tracking Loops

“…Zeng et al [27] compared the EKFbased tracking loop of GPS receiver with the CTL, demonstrating that the EKF-based tracking loop excels in both high dynamic and tracking accuracy. Nevertheless, the EKF algorithm is a sub-optimal filtering algorithm based on nonlinear functionalization and adopts approximation or neglect method for higher order terms to solve nonlinear problems [28]. In the case of strong nonlinearity, it may result in a significant estimation error and even lead to filter divergence.…”