群山地域에서의 GPS測位精度 解析

Analysis for Accuracies of Position Fix by GPS in Kunsan Area

The Global Positioning System(GPS) is a worldwide radio navigation system based on satellite technology. Signal availability and accuracy of GPS are subject to change due to an incomplete constellation and operational test activities. In order to analyze the signal availability and accuracy of GPS, we made an experiment on this system in Kunsan during April 6, 7. 9, 10, 1992. The results obtained are summarized as follows: 1. It was possible to avail the GPS system almost 24 hours per day, but sometimes it was impossible to obtain the GPS signal 2 or 3 times per day and its total time was at the most an hour. 2. By using satellite almanac. we also could calculate PDOP(HDOP) and forecast signal availability. And the mean positional error was 37.9-73.6m and standard deviation was 37.4-133.1m. The positional error almost coincided with PDOP(HDOP). 3. The mean positional error of 3D was less than that of 2D. And the altitude error in 3D was about 56-74m and its standard deviation was about 65-93m.