GPS and eLoran Integrated Navigation for Marine Applications Using Augmented Measurement Equation Based on Range Domain

Vulnerability to the interference of GPS (Global Positioning Systems) is one of the main obstacles to performing safe marine navigation. As eLoran (Enhanced Long Range Navigation), considered as the backup navigation system of GPS, has been developed specifically in several countries, the need for GPS / eLoran integrated navigation has emerged. This study represents the integrated algorithm for GPS and eLoran to overcome the vulnerability of GPS. The main research contents are as follows: a) Formula for integrated positioning of GPS / eLoran based on range domain is suggested. b) Essential ASF (Additional Secondary Factor) estimation filter to implement positioning by eLoran is presented in terms of real-time processing instead of employing ASF grid map, which should be pre-made at a local area and be distributed to marine users. c) Procedures for determining HPL (Horizontal Protection Level) are represented so that the reliability of the integrated navigation can be investigated. d) The marine test results are presented to validate the suggested methods based on the Loran-C signal. Test results show the integrated GPS and eLoran by the suggested methods can complement each other in terms of accuracy and reliability.