Study on the method of weak signals tracking using nonlinear filter

Under bad condition, GPS (Globe Positioning System) signals are too weak to be received, so High-sensitivity GPS positioning under any conditions is the problem that should be addressed at present. For the weak signals tracking, the nonlinear Kalman filter algorithm instead of the traditional methods used by standard PLL (Phase Locked Loop) and DLL (Delay Locked Loop). Simulation results confirmed that GPS receiver with new algorithms improved precision and robustness, which provides theoretical basis of the key technology of GPS receiver.