Design And Implementation Of GNSS Dual Mode Receiver Positioning Solution

The Global Navigation Satellite System(GNSS)positioning solution algorithm is the core part of the receiver.It is designed to have a high precision and low computational positioning algorithm,which is important for improving the practicality of GNSS in navigation and positioning.In order to improve the positioning accuracy,most algorithms introduce a weight coefficient matrix,but increase the amount of calculation,resulting in lower practicability.The satellite selection algorithm based on carrier-to-noise ratio has less computational complexity,but its positioning accuracy in satellite signal occlusion scenarios is low.Aiming at the above problems,the thesis designed and optimized the GNSS receiver positioning algorithm,and validated the algorithm based on the test development board.According to the principle of satellite navigation and positioning,the positioning solution module was divided into navigation message analysis module,satellite selection module,satellite's position and distance management module,and receiver position calculation module,the system implemented positioning solution function by calling the four sub-modules.Based on the design of positioning solution module,the model of dual-mode positioning algorithm was established,and the optimization scheme of positioning solution accuracy was systematically studied.The precision optimization scheme started from three aspects: measurement error correction,pseudorange smoothing filtering and the optimized satellite selection algorithm,and verified based on VC simulation platform.By comparing the advantages and disadvantages of the pseudorange and carrier phase measurements,the carrier phase smoothing pseudorange was employed.The optimized satellite selection algorithm module selected satellites with reliable signal quality from the successfully tracked satellites,which is based on the signal-to-noise ratio and pseudorange residual of the tracking channel.The C language programming of the dual-mode positioning algorithm was completed on the test development board,and the algorithm model was transplanted into the processor of the development board to realize the positioning solution function together with the dual-mode navigation baseband function.Through the transplantation and testing of the program,the performance of the receiver in the field fixed-point test and road test was evaluated.The test results show that the 95% accuracy error is 2.2275 meters in static scenes.In the dynamic scene,the 95% accuracy error of the open sky test is 7.2614 meters,the 95% accuracy error of the sports car circle test is 11.9466 meters,and the 95% accuracy error of the signal occlusion test is 18.9054 meters..