COMMUNICATIONS AND RADIO DETERMINATION SYSTEM USING 2 GEOSTATIONARY SATELLITES .1. SYSTEM AND EXPERIMENTS

We developed two types of hybrid terminals that can provide both satel lite communication and position determination services in one system. One terminal uses the single channel per carrier (SCPC) technique and the other uses the spread spectrum (SS) technique. To evaluate the per formance of the two systems, we carried out experiments in Japan and i n the Pacific Ocean using two geostationary satellites, ETS-V (150 deg rees E) and Inmarsat (180 degrees E). The ranging accuracy between the mobile terminals and the base station via the satellites was found to be about 200 m using the SCPC system and about 10 m using the SS syst em. The measured positioning accuracy was about 1 km in the SCPC syste m and about 600 m in the SS system when experiments were carried out n ear Japan. The experimental results show that the positioning errors w ere mainly caused by the orbital determination errors of the two satel lites. Presented here are the configurations and features of the SCPC and SS terminals, the experimental system, and the experimental result s.