• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.7
• /
• pp.1344-1349
• /
• 2012

The Korean DGPS station transmits the 200 bps GPS enhancement signal using the MSK modulation in frequency range of 283.5 kHz to 325 kHz. The land-based stations of 6 sites provide the service area of 80 km with the output power of 500 W. The ocean-based stations of 11 sites provide the output power of 300 W, which provide the DGPS service to 185 kM. Some places are serviced from two or three DGPS stations. The interferences among the DGPS stations using the high power can be occurred. Also, the performances of the user terminasl in dual service area can be degraded. In this paper, the protection ratios for the DGPS service are defined. Using the MF wave propagation model, the interferences among the DGPS stations and the adjacent wireless ground stations are analyzed. Also, the performances of DGPS user terminals are analyzed in the viewpoint of interference.

• Journal of the Korean Institute of Navigation
• /
• v.24 no.5
• /
• pp.405-415
• /
• 2000

DGPS/Radio beacons are currently being planned or installed in many countries. They offer a cost-effective way of distributing differential data to large number of users. These networks are also being deployed in South Korea, Japan, and China. Several DGPS stations among them are operating on the same frequencies. The DGPS signal based on a radio beacon in medium frequency band travels principally as a groundwave over the surface of the earth. The signal may also be received as skywaves at locations beyond about 100 km from the reference station. These skywaves interfere with groundwave signals due to fading. This factor has generally ignored in designing DGPS/Radio beacon systems. A further important factor is to reduce the coverage due to interference from other beacons on the same or adjacent frequencies. The desired signal may fade due to interaction between its skywave and groundwave components. It may degrade the accuracy of the positioning in a complex fashion. This paper estimates the coverage of Far East Asia DGPS stations which are operating on the same frequencies, which is based on the signal protection ratio and interference of the signal strength of the groundwave and skywave.