High Dynamic Gps Receiver Carrier Tracking Algorithm

This thesis focuses on high dynamic GPS carrier tracking. A new tracking method based on Square-root Unscented Kalman Filte(rSR-UKF) which is then implemented in HDL language is introduced to tracking the carrier.The SR-UKF is the same as UKF that does not need to linearize the system models so could get a more accuracy result in estimating nonlinear systems. On the other hand apart from UKF, the SR-UKF uses the sqrare root of the covariance matrix instead of covariance matrix itself during the filtering process, which could improve the numerical stability and guarantee positive semi-definiteness of the covariances, since the process of tracking carrier is nonlinear the SR-UKF can be used in it.After analysing the basic principle and the filtering process, SR-UKF is implemented into the GPS carrier tracking and the tracking algorithm is designed in detail. Compared with UKF and EKF, the SR-UKF was simulated with MATLAB, the result shows that the SR-UKF based carrier tracking algorithm is more stable than UKF and more accuracy than EKF.The algorithm is optimized for FPGA implementation. After optimization there are only up to 4 order matrix addition, matrix subtracting, matrix multiplication, matrix inverser, trigonometric function calculation and Cholesky decomposition, avoiding calculating the QR decomposition and matrix which order is higher than 4. The MATLAB simulation is carried out to validate the correction of the optimized algorithm.One of the main works of this thsis is the implementation of the optimized GPS carrier tracking algorithm based on SR-UKF. In this part, the design and implementation of every module of the optimized algorithm is analysed in detail. In the implementation the 32 bits single precision floating point number is applied. Simulating results in ModelSim of each model are shown. The top module simulating result shows that the FPGA implementation is correct.