Differential e-Loran Navigation System for Egyptian Coasts & Maritime
Farag Mohamed Bahr, Ezz Eldin Abdelkawy, Samy A.Shedied, Military Technical Institute, Egypt
Abstract: Ship navigation demands position fixing with a high degree of accuracy to enter the harbor mariner. The International Maritime Organization (IMO) has set a list of requirements which must be met by any electronic positioning system to be used on ships. The Global Positioning System (GPS) is most often the primary source of Position, Navigation and Timing (PNT) information. Due to the low levels of GPS signal strength at the surface of the earth and low jamming immunity, the recent concerns about vulnerability of GPS has sparked a renewed interest in the Loran PNT system. Enhanced Loran or simply “eLoran” is the latest version of Loran PNT for longstanding and proven series of low frequency navigation systems which are used to provide back-up capabilities to GPS in maritime navigation.
In this paper, we present a detailed proposal study to establish eLoran navigation system for Egyptian maritime harbors. This study uses the performance requirements for both non-precision approach (NPA) and maritime harbor entrance approach (HEA). The primary requirements of concern for NPA or HEA are the accuracy, integrity, availability and continuity. In the maritime sector, accuracy requirements are the most stringent and are considered the greatest challenge for eLoran establishment. Mitigating the sources of variation and error on Loran signal guided the design of eLoran. The simulation results for this proposal of Egyptian eLoran achieved the IMO's accuracy requirement of better than 20m. Our primary calculations for eLoran establishment show that the position accuracy at some harbors is around 40 m which is not suitable for HEA requirements. So, a suggestion for differential stations is also depicted in this paper to provide accuracy better than 20m. It provides eLoran navigation receiver with an up-to-date database of signal propagation corrections and real-time differential Loran corrections.