The coherent vector tracking loop design with FDE algorithm for BDS signals

This work presents a coherent vector tracking loop (CVT) for BDS signals based on cascaded filters. The structure of CVT is based on extended Kalman filters (EKF), including several local filters and a common navigation filter. A fault detection and exclusion algorithm (FDE) integrated to the tracking loop is introduced. This FDE method is used to detect and exclude the failed channel from the navigation filter. The benefits of the vector tracking in comparison of scalar tracking are also analyzed in detail. Evaluations are then conducted in both vector tracking mode and scalar tracking mode with blocked signals and signals with artificial jump of pseudoranges collected by a hardware BDS simulator. Results indicate that the vector tracking loop can operate in blocked signal conditions and can rapidly reacquire the attenuated signals compared with conventional scalar tracking method. Furthermore, the failed channel can effectively be detected and excluded by FDE approach to maintain the system to work normally.