Research On Model And Performance Of Dual-Frequency Multi-Mode Relative Positioning

The evolution of technology and the growing use of navigation and positioning applications have led to increased demand for precise navigation and location services.Precise relative positioning with characteristics of real-time and high precision is being used more and more widely in the actual navigation and positioning services and other fields,which provides technical supports for precise positioning of the majority of GNSS users.Especially with the continuous development and improvement of the GNSS system,the current available satellite resources are more and more,thus we can obtain more observation data simultaneously and the satellite geometric distribution is also more reasonable,which provides favorable conditions to relative positioning.Due to the similar signal modulation of GPS and BDS,their combined positioning is easier.However,GLONASS adapts to the frequency division multiple access signal modulation,which results in the existence of the inter frequency bias in relative positioning.Based on the fact that there is a linear relationship between the inter frequency bias and the satellite frequency,a new calibration method is proposed in this paper,that is to calibrate by sampling the inter frequency bias rate,then the method is calibrated and verified in the examples of the same and different brand receivers separately.This thesis establishes a single-system relative positioning model which adopts to the basic observation and the wide lane observations of carrier phase.Then,the parametric estimation is carried out by using the sequential least squares method,and the ambiguity is further fixed by the LAMBDA method,so that the positioning solution is completed.Seven positioning modes of the three systems that is GPS?BDS?GLONASS?GPS+BDS?GPS+GLONASS?BDS+GLONASS?GPS+BDS+GLONASS are compared and analyzed,and the following conclusions are obtained:1.Whether with the ultra short baseline or the short baseline,GPS has the highest accuracy and the strongest stability in terms of single system.BDS and GLONASS are significantly influenced by the number of visible satellites,besides,the fixed successful rate of BDS is higher than that of GLONASS.2.As to the dual-system,satellite geometric configuration is more enhanced than single system and the accuracy is also significantly improved.The accuracy of the three systems is not much better than that of the dual-system.The success rate of both the ultrashort baseline and the short baseline is more than 95%,and the positioning accuracy is 0.5cm and 5cm respectively.