LI Bofeng1 SHEN Yunzhong^1,2(1 Dept.of Surveying and Geo-informatics Engineering,1239 Siping Road,Shanghai 200092,China)(2 Key Lab.of Modern Engineering Surveying of SBSM,1239 Siping Road,Shanghai 200092,China)

In the rapid GPS positioning with carrier phase observations,the coordinate parameters and ambiguity parameters are highly correlated so that the float ambiguities resolved by least squares method are seriously biased.Therefore,it is difficult to correctly fix ambiguities.However,in the real applications,the various constraints exist in the coordinates or(and) ambiguities parameters.The constraints for coordinates can always be used to resolve float ambiguities with higher accuracy and the constraints for integer ambiguities can be employed to efficiently search ambiguities.Firstly,the general forms of constraint equations for coordinates and integer ambiguities are given;and the general solution is also derived.Each constraint equation for specialized situation is ulteriorly discussed in detail.At last,the numerical examples are implemented;and the results indicate that most of combinations of ambiguities can be rejected based on these constraints;and consequently success rate and efficiency of ambiguity resolution can be significantly improved.Therefore,the constraints should be fully used in GPS positioning.