FORECAST AND IMPROVEMENT OF SHIFT ERROR WITH GPS STANDARD POSITIONING SERVICE

摘要

Recently, GPS (Global Positioning System) has been spreading rapidly. Especially, SPS (Standard Positioning Service) was improved in 2000 by releasing SA (Selective Availability), and now it is paid attention from its confidence and usefulness. SPS is expected to be used various fields. First, we discovered that the position obtained by SPS shifts from true position. Then, we proposed the shift error reduction method using only satellites information (angle of elevation, angle of direction) from a GPS receiver. Next, we compared the result of simulation with that of positioning experiments with the index of an angle and a distance. As a result, we were able to forecast the direction of the shift and the amount of the shift and also were able to improve SPS precision.