Analysis of GPS and Loran-C performance for land vehicle navigation in the Canadian Rockies

Loran-C and GPS (Global Positioning System) were assessed for vehicular navigation along selected roads of British Columbia during the winter of 1991. The general topography of this mountainous area is described, together with the specific topographic features and tree coverage characteristics of the 2000 km of roads tested on the mainland and on Vancouver Island. The configuration and characteristics of the Loran-C Canadian West Coast chain along the roads used are described. The portable vehicle-mounted LORCAL (Loran Calibration at the University of Calgary) system used to collect and analyze the Loran-C and GPS signals along road profiles is described. The performance of Loran-C is analyzed in terms of signal to noise ratios, field strength, and time difference distortions, as measured by differential GPS. These distortions, which can reach several hundred meters over distances of less than 20 km, are analyzed in terms of topographic features. The possibility of using these time-independent distortions to calibrate Loran-C for use along the above roads is discussed. Masking of GPS signals due to topographic features and tree coverage along the roads is analyzed. A comparative analysis of Loran-C and GPS is presented in terms of signal availability and accuracy