Analysis of Very Long Baseline Accuracy Using GPS Data of the IGS

Because very long baseline measurement systems like VLBI, SLR have problems for practical use, there have been many studies to determine very long baselines using GPS which have many advantages for observation and data processing. For evaluating the accuracy of very long baseline using GPS, we obtained GPS data of IGS sites in and around Korea and precise ephemerides from IGS Global data center via internet. With those data, we carried out data processing according to observation durations, ephemerides, and data solution methods. As the result of this study, the relative accuracy of was deduced from two weeks observation data processing using precise ephemerides. In case of using precise ephemerides, its accuracy showed about 2 times better than that of broadcast ephemerides. This results can be used for the basic source for crustal movements study by GPS.