| In the distributed pseudo-satellite network positioning system,each independent clock on the pseudo-satellite generates a slight frequency offset and frequency shift due to different working start phases and surrounding environmental changes,making it difficult to synchronize the pseudo-satellite clocks in the network.Or the accuracy is not high,resulting in lower positioning accuracy.This paper studies the problem that the independent pseudo-satellite systems are not synchronized or the synchronization accuracy is not high.By designing a reasonable clock distribution scheme,the carrier phase observation equation is used to solve and optimize the clock difference between pseudolites.Thereby achieving high-precision synchronization of the system distributed clock.Based on the study of various clock error calculation and optimization algorithms,a clock difference calculation and hybrid optimization algorithm based on known position is proposed to achieve high-precision synchronization requirements for the system pseudo-satellite clock.At the same time,according to the characteristics of monitoring applications,monitoring the slow and small changes of receiver position,a multi-epoch based receiver position and clock difference algorithm is proposed,which can greatly simplify the clock distribution of pseudo-satellite system and reduce the requirements.Difficulties in clock distribution for pseudo-satellite systems.In order to accomplish the objectives of the project,This paper mainly completed the following research work:(1)Construction of algorithm research and verification platform.Complete the design of pseudo-satellite system structure and parameters,determine distributed clock distribution and synchronization scheme,and construct pseudo-satellite experiment and test system.According to the characteristics and needs of algorithm research,based on the existing pseudo-satellite receiver,Matlab is an algorithm research tool and establishes an algorithm experimental verification platform.(2)The pseudo-satellite system clock difference solution based on single difference.Aiming at the clock synchronization problem of pure pseudo-satellite system in high-precision positioning,the dual-antenna reference receiver and carrier phase observation equation are used to adjust the carrier phase integer ambiguity by the least squares estimation search(LAMBDA)method.The solution method of the pseudo-satellite system clock difference of the difference mode can realize the high-precision synchronization of the system clock by the clock difference broadcast or centralized processing.The simulation and experimental results show that the solution and hybrid optimization algorithm of pseudo-satellite system clock difference based on single-difference method can effectively solve the problem of distributed clock synchronization of pseudo-satellite system.The clock error is high,the technology is feasible,the method is simple,and it has certain Engineering technology reference value.(3)Research on clock difference optimization algorithm.The solution of the clock difference in the system is completed by solving the clock difference of the pseudo-satellite system based on the single difference method.On this basis,a hybrid optimization algorithm(HOA)is proposed to achieve further optimization of the clock difference.The feasibility and correctness of the proposed method in distributed networking positioning system are verified by simulation verification and positioning solution.(4)Experimental testing and verification of the algorithm.On the pseudo-satellite experimental verification platform,the carrier phase experimental data is extracted by the pseudo-satellite receiver,and the pseudo-satellite clock difference and position are solved by the MATLAB software,and the clock difference and position are solved,the verification algorithm is used.Accuracy and actual results. |
