Studies On Precise Relative Positioning And Velocity Determination Technologies Based On Compass

At present, the research on relative positioning and velocity determination mainly based onGPS satellite navigation system, while with the development of Compass satellite navigationsystem construction, the studies on relative positioning and velocity determination based onCompass satellite navigation system also becomes urgent and meaningful. Reference for therelated studies about GPS, the research and consequence being contained in this paper are asfollows.(1) The mathematical model of GNSS relative positioning is given, the error factors whichaffect the accuracy of positioning are analyzed, and several methods to abate these influences areintroduced. The feature of Compass relative positioning is simply introduced.(2) The application of methods on cycle slips detection and repair used in Compass real dataare studied. Some methods to detect cycle slips are introduced, on these methods, the residuals ofcycle slips are calculated. According to the definition of triple frequency combinationobservation, the errors of combination observation are analyzed. Based on the least-varianceprinciple, three linearly independent observations composed of Geometry-free combinationobservations and Melbourne-wubbena combination observations are obtained. Then the test ofcycle slips using Compass real data is made, the result shows these three linearly independentobservations can detect cycle slips completely and detect gross error up to0.1cycle.(3) Basic steps of the solution for relative positioning are discussed. According to thetheoretical foundation of Kalman filter and LAMBDA, the combination method of Kalman filterand LAMBDA is applied to calculate ambiguity. The correctness of relative positioning programmodule designed by author is proved by a numerical example based on zero-baseline real data.Using Compass real data, several tests are made for the times of searching ambiguity, theselection of the Ratio threshold and the rate of fixing ambiguity, the results show that when theambiguity Ratio threshold is set at3,the fixed solution’s accuracy of horizontal direction is about1cm, vertical direction is about3cm. Finally, examples based on different frequency of Compassreal data is made, the results show that the single frequency of B3data can reach a goodaccuracy.(4) The Mathematical model of velocity determination with Doppler measurement isdiscussed, the effects of error sources on velocity determination are analyzed. Based on theCompass real data, the accuracy of single point velocity determination with raw Dopplerobservations for examples is studied. The results show that the frequency of B3Dopplerobservations used for velocity determination can reach a higher accuracy than B1and B2, whenthese three frequency of Doppler measurements used at the same time, the accuracy of raw Doppler measurements can be better than the0.1m/s, realize the nominal accuracy of0.2m/s.The accuracy of relative velocity determination with carrier phase difference Dopplerobservations and raw Doppler observations for example are studies. The result shows that,theaccuracy of relative velocity determination depends on the precision of observations.(5) Finally, in the Windows XP operating system environment, using Visual Studio2005C#software programming, this paper design the relative positioning and velocity determinationprogram module what can realize above-mentioned process.