Algorithm of multi-epoch trajectory determination

GPS is the most used navigation system in today's transportation world. However the performance of GPS decreases in mountains, valleys, urban canyons, where it is not always possible to track enough satellites to calculate the 3-D position. This paper outlines a new method to improve the performance of GPS positioning service, especially for fixed-route transport (train or bus). The algorithm of multi-epoch trajectory determination (METD) is based on multi-epoch observations with Least Squares Adjustment (LSA) to track the trajectory of the moving object. The result is satisfactory, even when the current visible satellites are insufficient.