Korean SBAS, 'KASS'
GPS data readings from an aircraft, ship or smartphone have significant positioning because of the time delay caused by refraction of the electromagnetic signal emitted by a satellite outside the earth’s atmosphere as the signal passes through the ionosphere and atmosphere.
As such, WAAS in the USA, EGNOS in Europe, and MSAS in Japan have been developed to reduce the margin of error using a geostationary satellite.
SBAS is a system which accurately corrects GPS errors in real-time using the geostationary satellites and then broadcasts these messages to its users over a wide area. SBAS is consisted of five main segments and the main function of each segment is described as below;
- Reference station: collects measurement data and broadcast messages from GPS and forward them to Processing stations.
- Central processing station: receives GPS data from Reference stations and performs correction information and integrity information.
- Satellite communication station : generates “GPS-like” ranging signals combined with SBAS messages from Central processing stations and transmit them to Geostationary satellite.
- Geostationary satellite: The Geostationary satellite broadcasts the received SBAS signal to users within the service area.
- Operation and maintenance: monitors system performance and carries out the necessary corrective and maintenance operations.
The ground observation station measures another environmental factor that can affect the signal received by one or more GNSS satellites, satellite signals or users. It then uses these measurements to generate data which are then sent to one or more broadcasting satellites for transmission to the final user.
KARI is developing the Korea SBAS to provide customized navigation data to sky, ground and offshore users by correcting the current GPS error level in real-time.
The KASS project is supervised by MOLIT and led by KARI, with the participation of ETRI, KRISO, and TTA. Upon completion of the ‘KASS’ project, Korea is expected to become the seventh country after the US, Europe, and Japan to own an SBAS.
KASS will provide the precision location data to all areas except the aircrafts beginning in July 2019. Throughout 3 years of verification procedure and stabilization period, the service will be expanded to all aircrafts navigating inside Korea's flight information region beginning in October 2022.
As the data will be provided by satellite free of charge, all terminals using GPS data will be able to utilize the data with nothing more than a software upgrade, without requiring any additional terminals.
Upon completion of the development of KASS, the expected annual benefits in the aviation sector include a 75% reduction of air accidents, a 53,000t reduction of carbon emissions, and a saving of 42,000 barrels of fuel. Meanwhile, benefits in the location-based service area will include the improved performance of information and communication devices, a reduction of automobile navigation errors, the prevention of marine accidents, indoor location tracking, and rapid identification of the location of senior citizens, lost children, and emergency situations.