Research On Signal Tracking Technology Of GPS Receiver In High Dynamic

After years of development, global satellite navigation system ( GPS ) now has been applied in many fields, aerospace, missile guidance, geodetic survey, intelligent transportation need positioning services provided by the navigation. At present, low dynamic receiver tracking algorithm has been able to meet the need in tracking accuracy, but in high dynamic environment, due to the speed of the receiver and satellite, the acceleration is very high,making the signal contains a lot of Doppler frequency shift and its rate of change,the traditional receiver has a large tracking error, and even loss of lock. In this paper,the high dynamic receiver signal tracking algorithm is studied,in order to improve the tracking performance of the receiver in high dynamic. The main work of this paper can be summarized as follows:Firstly, the principle of signal tracking and the traditional signal tracking loop are studied.The limitations of traditional receiver are analyzed, including the carrier tracking loop and the code tracking loop. The receiver carrier tracking loop is usually applied to the traditional structure of FLL assisted PLL. In high dynamic situation, the loop must use large noise bandwidth to improve the dynamic performance, but the larger bandwidth makes the noise increases,resulting in tracking error increases,and even the loss of lock. In this paper,a high dynamic receiver signal tracking loop is proposed, considering the effect of high dynamic.The Vector Delay Lock Loop is studied. Considering good performance of code tracking loop, code tracking loop generally will not lose lock in high dynamic condition. However, the satellite signal received by the receiver in high dynamic is often unstable, which may occur in the case of a satellite signal transient and weak or even disappeared. So this paper proposed a Vector Delay Lock Loop based on EKF. Tracking performance of the Vector Delay Lock Loop and the traditional code tracking loop is compared under simulation of a satellite signal shielding case.The carrier tracking loop of dynamic tolerance is weak,high dynamic and great Doppler frequency shift and the change rate make carrier tracking loop generate big error and even lose lock. So this paper design a new carrier tracking loop by using UKF to instead of discriminators. By observation of the I,Q branch coherent integration,the accurate estimation of carrier phase error, carrier phase error, carrier Doppler and their derivatives are obtained.Based on the vector delay lock loop, the design of the whole signal tracking loop is completed.Finally, the performance of the signal tracking loop is verified by simulation data and real data.