چكيده به لاتين
Abstract:
Satellite navigation systems provide accurate information anywhere in the world for users. The signals received from satellite navigation systems have two features of broadband and low power. These two features make the signals very vulnerable in return noise, all types of disturbances, or in urban environments under difficult conditions such as signal degradation, high dynamic and blocked signal. Because in this situation, the amount of signal strength decreases, which greatly affects receiver performance. For this reason, it is necessary to design the receivers in such a way that they can receive weak signals or missing signal to extract navigation data. This thesis presents a method based on the Kalman filter for tracking section under harsh environments. In tracking section, the goal is to obtain the exact quantities of the code phase and carrier frequency. First in the proposed method, the tracking using the two-variable and four-variable Kalman filter that the four-variable Kalman filter dramatically improves navigation response and improves the RMSE by as much as 2/04 meters. Then, for the dynamic scenario, the combination of GPS and GLONASS has been used. In the tracking section of this combination system, the four-variable Kalman filter is placed and has better performance than traditional combination receivers. Then, a review of the vector tracking method is introduced, and finally, the Dempster Shafer algorithm is introduced as the intelligent unit to select the most appropriate code-phase error value. By providing this proposed method, a significant improvement has been achieved in reducing the phase error of the code and the receiver function.
Keywords: Navigation Systems, weak Signal, Kalman Filter, Vector Tracking, Dempster Shafer.
