Multipath parameters estimation of weak GPS signal based on new colored noise unscented Kalman filter

Multipath is one of the dominant error sources of code tracking in indoor and other harsh environments. In this research work, a new colored noise unscented Kalman filter (UKF) is introduced to estimate the multipath parameters of weak GPS signal. For improving the carrier to noise ratio, it uses a block-averaging signal pre-processing method (BAP) to process the received weak GPS signal. The signal after pre-processed is used as input of the multiple correlators. The In-phase and Quadrate phase values of multiple correlators are used as the observational measurements of UKF to estimate the code tracking´s multipath parameters such as amplitude, code delay, phase, carrier Doppler. The simulation results show that this method can effectively estimate multipath parameters of weak GPS signal, of which carrier to noise ratio is down to 21dB-Hz, so it proves the effectiveness of this method.