Estimation of DGPS Carrier-Phase Errors Using a Receiver Network

Wednesday, August 16, 2000 - 3:50pm - 4:45pm
Keller 3-180
John Raquet (Air Force Institute of Technology)
Current approaches for obtaining the most accurate GPS positioning, based upon differential carrier-phase ambiguity resolution, encounter significant performance degradation as the distance between the mobile and reference receiver increases. This presentation will describe an approach for using a network of reference receivers to perform precise, cm-level positioning over a large geographical region. This approach, called NetAdjust, is a linear minimum variance of error estimator, and it can be shown that it is equivalent to least-squares collocation and also to a least-squares condition adjustment. All three of these viewpoints provide unique insights into the operation of the NetAdjust algorithm. Both theoretical and actual results from field tests will be presented, highlighting the strengths and limitations of using a network of reference receivers for precise positioning.