Estimating the Optimum Duration of GPS Static Observations for Short Baseline Length Determination in Greece

SUMMARY Cost-effecctiveness is a requirement of most geodetic projects. In order to estimate the minimum duration of GPS static observations to determine an optimum, cost- effective accuracy in baseline length measurements, a statistical analysis of data collected during a 6day long record, in the framework of the GERCOP project, were analyzed. Using a random number generator we defined each time 9 sets of observations, 15min to 3 days long from this 6-day record. These sets of data were analyzed on the basis of postprocessing static analysis and a commercial software, and the corresponding baseline lengths were computed. The differences between the average and maximum estimated baseline length for each data set from the best estimate baseline length and their standard deviation were subsequently computed. A plot of the obtained result versus time revealed an exponential trend for the decay of the uncertainty of the baseline length versus time. This analysis reveals that only a slight improvement in the accuracy of the baseline length is obtained after 3 and definitely after 24 hours of observations. This indicates that the optimum duration of GPS static observation for short baseline length measurements in Greece is 3 hours.