Research On GNSS Single Epoch Baseline Solution

GNSS Single epoch positioning algorithm is immune to cycle slips and can be immediately re-initialized after loss-of-lock,providing high availability.High-precision positioning requires the fast and correct fixed ambiguity.Although the high efficiency and reliability of dual-frequency single epoch ambiguity fixed is verified in the practical application,its performance is vulnerable to the impact of the observation environment.And the single-frequency observations usually need a few minutes to complete initialization influenced by the number of tracking satellites,the length of the baseline,and the observation environment.The combination of multiple GNSS systems provides new ideas and data support for ambiguity fixation.For single epoch ambiguity fixation and its baseline solution,the paper focuses on the study in the following four aspects:This paper briefly introduces the general situation of GNSS and the causes and solutions of ill-posed problems in surveying.The key is to analyze the combination of GPS and BDS.Based on the double-differential carrier equation,the reason of the ill-condition in the single epoch ambiguity resolution is analyzed.And a single frequency single epoch ambiguity resolution method based on regularization is proposed for the short baseline.The method adopts only single frequency carrier phase.The problem of rank defect and the least squares floating point solution not credible is reduced by means of regularization theory.Meanwhile,the success rate of ambiguity fixed is improved.Aiming at the problem that the fixed rate of single epoch ambiguity is low for the medium-long baseline,a two-step regularization based on the short baseline single epoch ambiguity fixed method is used to realize the double-frequency single epoch ambiguity fixed.That is,the pseudorange and wide lane carrier were combined,joining a regularization,to achieve wide lane ambiguity fixed.On the basis of the previous,construct the ionosphere-free combination,joining a second regularization,to realize single epoch original carrier ambiguity fixed.The problem can be more difficult as the troposphere parameters are highly correlated with the height component.In this paper,the decorrelation matrix is constructed by using the tropospheric delay parameters,and the influence of the number of tropospheric parameters on the decorrelation is considered.Respectively,use two parameters and a parameter to conduct baseline solution.The results show that considering the effect of a troposphere parameter is better,the accuracy of the vertical direction is improved effectively.The accuracy baseline resolution of the 56 km is millimeter.And that of 170 km is better than 2 cm.