Analysis of Discriminator Based Vector Tracking Algorithms

In this paper, a variant of the vector delay lock loop (VDLL) tracking algorithm for tracking the L(1) civilian GPS signal is introduced. The algorithm functions on the principle originally described in [1]. The VDLL architecture uses a single Extended Kalman Filter to predict the satellite PRN code phase and track the user's position, velocity, and clock states. Additionally, a series of separate Kalman filters is used by each channel to track the satellite carrier signal. The advantages of the vector/Kalman filter based architecture over traditional methods are explained. The ability of the vector tracking algorithms to rapidly reacquire blocked signals is analyzed using data produced by a Spirent GPS simulator. The vector tracking algorithms performance is also compared to traditional methods using tracking loops. The VDLL is shown to outperform the traditional methods.