OBSERVING-SESSION DURATION OPTIMIZATION OF GPS DEFORMATION NETWORKS USING POINT-SENSITIVITY ELLIPSES

Abstract

This study investigates the relationship between GPS observing session duration and sensitivity, measured using non-centrality parameters. TUSAGA-AKTIF (T & uuml;rkiye's CORS-TR) network with 15 stations was used for this aim. Data with 4h, 6h, 12h, and 24h observing session durations from three sequential days in 2011, 2012, and 2013 were analyzed using Bernese 5.2 GPS software. The repeatability of the daily solutions for each year was carefully analyzed to properly scale the Bernese cofactor matrices. The root mean square (RMS) values for daily repeatability relative to the combined 3-day solution were computed (generally less than 2 mm in horizontal directions (north and east) for 24h observing sessions). For each yearly dataset, a comparison of non-centrality parameters revealed a linear relationship between session duration and non-centrality parameters. Using the cofactor matrices obtained from these observing sessions, the minimum detectable displacements along the maximum eigen directions were compared. Results showed that longer session durations led to smaller minimum detectable displacements, establishing a linear relationship between observing session duration and minimum detectable displacement. Finally, sensitivity ellipses were drawn using the minimum detectable displacement parameters.