Figure 1 shows current status of the continuously operating GPS stations for geodetic and cadastral surveying established by Korean government. The station is equipped with the latest dual-frequency receiver. A receiver, a modem, a power supply and a tiltmeter are installed inside the pillar. The collected data at each observation station are transferred to the data center with the high-speed modem through public telephone lines. At the data center, the collected data are processed automatically using precise baseline analysis software to estimate 3 dimensional coordinates.
Data processing is done repeatedly depending on ephemerides prepared.
Calculations of baselines and positions are carried out using the broadcast ephemerides within 3 hours after the data acquisition. Alternative calculations are done to get final results using precise ephemerides prepared by IGS about 11 days later after the observations. The network will be the backbone of the newly established precise geodetic network in conjunction with the conventional triangulation network. The Korean Datum employs the Bessel ellipsoid as a reference with its origin fixed at Tokyo, Japan. While the request for the coordinates referenced to the existing datum are still large, demands for the well-accepted global coordinate systems have been also increasing a lot.