Information Matrix Algorithms to Produce Least Independent Close Loops in GPS Network

To address the problems of multiple solutions and indefinite ring length in the classical independent closed loop algorithm,using the closed ring-shaped information matrix and taking into account the side element,this paper introduces a new algorithm based on matrix operations.The resulting closed loop meets all the requirements of the least independent closed loops.Through comparing the results of two algorithms in GPS network closed loop researching,the uniqueness of the result and the shortest length of ring are verified.