A RAIM Method of Pseudo-range Residual Based on Positioning Result of Proportion of Visible Satellites

The conventional receiver autonomous integrity monitoring (RAIM) algorithm of pseudo-range residual causes large residual error without a relatively accurate priori receiver position, which may lead to fault detection and identification. Therefore, measurements with gross errors may be used in positioning instead of high quality ones, especially when there are more than one measurement being distorted by gross errors. Meanwhile, the accuracy of the positioning result will be seriously deteriorated. In order to solve this problem, a new robust RAIM algorithm with positioning result based on the proportion of visible satellites is proposed in this paper. Using the proportion of visible satellites, the new algorithm produces a coarse position by the least squares method to calculate the pseudo-range residual. Accordingly, a robust approach to evaluate the accuracy of the coarse position based on the least median square (LMedS) is also proposed to make sure the position can meet the requirements of the following fault detection. In addition, the threshold mentioned in the new algorithm is derived theoretically. Finally, the performance of the new algorithm is good in simulations and real-data-tests, compared with conventional approaches. Results show that under the complicated scenarios the new algorithm can provide a considerable reduction of the probability of miss detection (7.89 % in this test), and improve the positioning accuracy remarkably.