Research On Satellite Positioning Algorithm Based On Pseudorange Data

Satellite navigation system can provide unified temporal and spatial information,which relates to varied aspects of national economy.Realizing positioning process by satellite navigation receiver has the advantage of strong applicability,high efficiency and wide application range,which has great development potential.For the urgent need of positioning method with higher precision,many researchers at home and abroad have carried on key research to satellite positioning technology.Based on the construction of satellite navigation product certification center of CETC-54,this project study on satellite positioning algorithm based on pseudo range observation and give the comparison of algorithm performance with measured data.The main content of this paper can be divided into the following four parts:First of all,satellite positioning belongs to the application of passive location method in the satellite navigation system,based on a clear understanding of research status at home and abroad,this paper first analyze the develop trend and existing problems of passive location system,then focus on the description of basic issues such as the composition of the satellite navigation system,signal structure,space-time coordinate system and reading method of observation file.Then this paper elaborates the method of calculating the position of satellites and complete the simulation of satellite position and pseudorange by using receiver measured file.At the same time this paper analyzes and corrects and common sources of error and its interface on positioning result in pseudo range single point positioning,which lay a foundation on more accurate user positioning with corrected pseudorange.Then this paper gives the research on positioning algorithm,in this part we complete the calculation of user's position with least squares positioning method based on pseudorange measurements.This method does not consider the influence on ranging accuracy of varied elevation angle of satellites,by introducing weight coefficient matrix we adjust the cost function and reduce the positioning error caused by the non equal precision observation.Contrary to the the error increasing caused by frequency domain design which leads to isolated positioning results in different time of the least square and weighted least squares algorithm,Kalman filter which use time domain design method is introduced and the process of satellite positioning is defined.According to strong nonlinear characteristic of satellitenavigation system we compare the improving method of Kalman filter in nonlinear environment and choose the unscented Kalman filter,after establishing the observation model and the state model,the unscented Kalman filter algorithm is used in positioning process.At the end of this paper,the theoretical performance of three kinds of localization algorithms(least square method,weighted least square method,unscented Kalman filter algorithm)are analyzed,we explain their respective advantages.Under the premise of considering the error source we calculates the user position by three algorithms from same observation file and compare the performance of algorithms through the error analysis in the way of comparing the positioning result with the user location determined by precise ephenents.The unscented Kalman filter algorithm adapt to the demand for higher positioning accuracy requirements,the simulation results are in consistent with the theoretical analysis conclusion and can achieve expected results,which provides reference for further research on satellite pseudo range positioning algorithm as well as certain reference value for the construction of satellite navigation system.