Indirect-Inversion A lgorithm via Precise Integration for Ill-Conditioned Matrix in Ambiguity Resolution

Global navigation satellite system(GNSS)positioning depends on the correct integer ambiguity resolu-tion(AR).If the double difference equation for solving the float solution remains il-conditioned,often happening due to the environment complexity and the equipment mobility,the corrcct AR is difficult to achieve.Concern-ing the il-conditioned problem,methods of modifying the equation cofficient matrix are widely applied,whose effects are heavily dependent on modifying parameters.Besides,the direct inversion of the il-conditioned coef-ficient matrix can lead to a reduction in the accuracy and stability of the float solution.To solve the problem of il-conditioned matrix inversion and further improve the accuracy,the present study for the first time proves the positive definite symmetry of the coefficient matrix in AR model and employs precise integration method to the indirect inverse of cofficient matrix.AR model for the GNSS positioning and the general resolving strate-gies introduction are briefly introduced.An indirect-inversion algorithm via precise integration for il-conditioned coefficient matrix is proposed.According to the simulations and comparisons,the proposed strategy has higher precision and stability on foat solution,and less dependence on modifying parameters.