GPS/Loran-C: An Effective System Mix for Vehicular Navigation in Mountainous Areas

Abstract

The main characteristics ofboth GPS (1.5 GHx) and Loran-C (1OOkHz) navigation systems are reviewed, with emphasis on vehicular navigation applications. The effects of the GPS line-of-sight requirement and of Loran-C signal attenuation in mountainous areas are illustrated using signal availability statistics collected for major roads located in British Columbia, Canada. The advantages of an integrated GPS/Loran-C system are demonstrated using GPS and multichain digital Loran-C receiver data collected along a 230 km road section. Signals sufficient for horizontal navigation (HDOP 5 5) are available approximately 60 percent of the distance in the case of GPS, 75 percent in the case of Loran-C, and some 95 percent in the case of GPS/Loran-C. The advantages of multichain versus single-chain Loran-C receiver operations in mountainous areas are also demonstrated. A performance analysis of the digital Loran-C receivers used for the tests is presented.