GPS versus Loran-C for vehicular navigation in urban and mountainous areas

The main characteristics of both Global Positioning System (GPS) and Loran-C (LF) navigation systems are reviewed, with emphasis on vehicular navigation applications. The effects of the GPS line-of-sight requirement and Loran-C signal interference and attenuation in urban and mountainous areas are discussed. Unaided GPS and Loran-C signal availability statistics sufficient for 2D positioning with HDOP < 5 are presented using GPS and Loran-C signal statistics. In Calgary, GPS availability is found to be better than Loran-C. This is attributed to a near complete satellite constellation and to the use of a fast signal acquisition GPS receiver. The use of integrated GPS/Loran-C improve GPS availability by only a few percent. In the mountains, the use of an integrated system increases availability to 95% as compared to 65% for GPS and 75% for multi-chain Loran-C.