In existing satellites, Inter-Satellite Link (ISL) was used for purposes such as determining orbit, controlling clusters of small satellites, and synchronizing clocks. When ISL is applied to navigation satellite, it has advantages such as decrease of ground reference station, reduction of atmospheric influence, and reduction of influence of signal disturbance such as jamming. GPS uses ISL for the Autonav function. Autonav guarantees the integrity of the system for approximately 180 days without the control of the ground reference station. ISL was used mainly for system management but not for user positioning. Using range measurements between navigation satellite such as ISL in positioning can improve accuracy by increasing measurements. However, ISL is currently not available for user. Thus, a positioning method for generating range measurements between navigation satellite using broadcast ephemeris has been studied. In this paper, range measurements between navigation satellites are simulated using Final Product of International GNSS Service (IGS) as well as created using existing studied broadcast ephemeris. It analyzes accuracy of measurement according to type and accuracy of measurements that can be used as range between navigation satellites.

Keywords: GPS, ISL, ephemeris