Research On GPS/BDS Precision Relative Positioning Technology

Satellite navigation is a precise method for measuring the position of any point on Earth and time through a global satellite navigation system(Global Navigation Satellite System,GNSS).Currently,satellite navigation receiver provides personal positioning,multi-purpose commercial positioning,navigation,surveying and measuring precise time.In civilian areas,satellite navigation systems promote the profound changes in the global transportation occurs.It is widely used in land,sea and air transportation navigation.In the military field,the application of satellite navigation system is also very extensive.Assess and combat the effects of precision-guided,autonomous navigation full-time domain.The future soldier combat system security,military digital communications network when granted..Many areas command and control various combat platforms such as have a wide range of applications.Although the GPS satellite navigation system technology is more mature.GPS is currently the most widely used to satellite navigation system.But GPS is still a lot of problems in terms of reliability,integrity and other fields.Therefore,in order to meet the higher positioning accuracy of the plurality of composition and properties of the navigation system while used together.In this way,peple will greatly increase the navigation of observables and improve the quality of navigation and positioning services,They also improve the performance of the overall portfolio positioning system and the expansion of satellite navigation applications.In recent years,with the rapid development of the Beidou satellite navigation system,GPS / BDS portfolio positioning technology has become a major research directions in the field of satellite navigation.Therefore,this paper researched the theory and method of GPS / BDS combination of relative positioning,the design of the core algorithms related to the preparation of the relevant procedures,and the measured data is verified by the theory and methods involved.The main work and conclusions are as follows :1.The paper described the observation model GPS / BDS relative positioning.It included non-differential observation,single difference observables,double-difference observables.Studied the error model GPS / BDS relative positioning.It included satellite orbit errors,satellite antenna phase center variation,ionospheric refraction delay,tropospheric delay,receiver antenna phase center variation,effects of multipath and observation noise and correction methods.2.Some problems of GPS / BDS relative positioning exists studied.First I studied the temporal benchmark portfolio positioning reunification.Existing solutions are given.I studied the theory of linear combinations of dual-frequency observations.To locate and select the standard combination of observations are described.Respectively ionosphere combined GPS and Compass systems,wide-lane combinations,combinations alleys,wide lane combinations analysis.I pointed out the advantages and disadvantages of these types of combinations and studied the double difference observation model based on GPS / BDS portfolio constructed.For the case when the group is selected in accordance with the same dual-differential systems and different reference satellite systems were analyzed.And I give the solution.Then I described the right approach given several existing GPS / BDS relative positioning.Including rights law,such as the height angle given rights law,the error probability density function of a given distribution law rights law,Helmert variance component estimation given rights law.And the elevation angle given on the basis of the right to be raised GDOP rights law.I conducted a numerical example.By comparison with the elevation angle given rights law,I proved the effectiveness of this method.3.The paper studied GNSS integer ambiguity estimation process.I'm fuzzy Kalman filter method estimates the degree of real solutions is discussed.I set out the basic Kalman filter model and based on real ambiguity estimation method using a combination of pre-positioning and to study the two-way filter for filtering,and gove its advantages and scope.I described the classic and most widely ambiguity search algorithm(LAMBDA method).And for the continuous use of common ambiguity search method solver,if the previous epoch ambiguity solver poor results,the current epoch solver results will be affected,and this effect is more obvious when initializing problem,using a before and after taking into account the epoch ambiguity search method.The results take full advantage of multi-epoch information,and complete use of LAMBDA method to search ambiguity after further testing.A former Ambiguity improved the accuracy of the results solver.I reduced initialization time.Through the measured data to verify the availability and advantages of this method,I describes the criteria for determining the degree of ambiguity.Commonly used Ratio test,observation residuals,phase residual polynomial fitting method to test the theoretical analysis.4.I described the general steps GPS / BDS relative positioning solver while preparing the GPS / BDS relative positioning procedure.I showed the flow chart of the main modules.Through the measured data,the use of written procedure for GPS / BDS static relative positioning and relative positioning data processed dynamic precision analysis results.The results showed that: a combination of the system greatly increased the number of visible satellites.Satellite geometry spatial distribution of the intensity compared to a single system has improved significantly.Treatment from 31.5km to 72 km length of six different baseline static mode.E direction of maximum positioning error is 1.95 cm.N direction of maximum positioning error is 1.72 cm.U direction of maximum positioning error is 4.16 cm.For relative positioning of the dynamic experiment,the minimum length is the baseline 0.4km.The maximum length is 25.8km.The GPS / BDS result of a combination locate the program.And GrafNav software solver results were compared to verify the availability of self procedure.Program use self GPS / BDS dynamic relative positioning accuracy up to cm level.5.The paper analyzed the satellite elevation angle of 10 degrees,15 degrees,30 degrees,40 degrees impact on positioning.In a static simulation of dynamic positioning,height cut-off angle of 15 degrees positioning accuracy compared to the 10 degrees,30 degrees is better.Positioning accuracy combined system to be slightly higher than the single system.When the height is higher than the cut-off angle of 40 degrees,a single system can be observed to reduce the number of satellites.Even a single system for a long time can't be fixed solution.Combined system can increase the number of visible satellites and space geometric distribution strength.In the case of poor observing conditions were still able to meet the needs of precision positioning.Broaden the satellite navigation applications.Increased the ambiguity fixed rate.It is high stability and availability.