Carrier-Phase DGPS System Accuracy Tests: Increasing Baseline Distance and Using CORS Network Data

摘要

Boeing Flight Test performed a flight test to determine the maximum baseline distance that a carrier phase differential GPS system can operate within and still meet the high accuracy requirements of validating autoland systems. The Boeing 737 airplane used was equipped with Boeing's Differential GPS Aircraft Positioning (DAP) System in which the truth reference site is always placed within 10 km. of the test location. As the airplane flew a round trip path covering over 2300 km, data was collected from 6 ground stations. The carrier solution was analyzed to determine the maximum distance a differential ground station could be placed and still meet the accuracy requirements of 1.5 ft, in the x-, y- and z- directions. This paper shows the results of this one-day test. Additionally, it is valuable to any differential GPS system to be able to use data collected by reliable outside sources such as the Continuously Operating Reference Station (CORS) network of receivers. For this analysis, several sites near where autoland testing occurred were used to compare the results of using CORS data sampled at various rates at various distances as the reference site to the data received from the Boeing reference receiver placed within 10 km. of the test. The test parameters and the results of these tests are discussed in detail. This paper shows that very accurate carrier phase differential results can be obtained using much longer baseline distances than originally thought. It also shows that CORS sites can be used as reference sites with few restrictions with respect to the CORS data rates or baseline distances.