Demonstration Project Results of GPS·C Wide-Area GPS Corrections for Remote Areas including the Arctic

摘要

Wide-area differential GPS offers significant advantages for special needs users, such as Canadian Coast Guard (CCG), and the Canadian Hydrographic Service (CHS) for their Canada-wide operations, particularly in remote areas of the country. The Geodetic Survey Division of Natural Resources Canada (NRCan) has developed a system of nation-wide GPS corrections or GPS·C. GPS·C provides real-time GPS corrections for distribution and broadcast throughout Canada. The corrections are made available in standard RTCA-159 or RTCM-104 formats for direct input to GPS receivers.rnThe CCG provides a Differential GPS "Initial" operating service (CCG DGPS) for general navigation in identified high traffic areas of the Canadian Waterways System. GPS·C's RTCM-104 format is compatible with the CCG Differential GPS Navigation Service.rnA joint Canadian Coast Guard, Canadian Hydrographic Service, Geographic Data B.C., TMI Communications, Cygnus Satellite Systems Corp. and NRCan GPS·C demonstration project was conducted from mid-July to mid-October 1998. The data collection phase of the project took place on board the CCG vessel "CCGS GRIFFON" on a voyage from Prescott, Ontario to Churchill, Manitoba via the St. Lawrence River, Gulf of St. Lawrence, Labrador Coast, Davis Strait, Hudson Strait and Hudson Bay. The first half of this 4700 km route was within coverage of the CCG DGPS Navigation Service. GPS·C corrections were delivered to the vessel, for the entire voyage, using the MSAT mobile satellite service. An onboard computer system processed RTCM-104 corrections from both GPS·C and CCG DGPS providing continuous real-time comparisons of position differences between both systems. Stored raw data and GPS·C positions were analyzed, in post processing, to determine the performance of the system outside the CCG DGPS coverage area.rnThe paper presents the initial evaluation of positional accuracy resulting from the use of GPS·C outside of the CCG DGPS Navigation Service. The results show that GPS·C corrections, via the MSAT link, were available and reliable for the entire voyage to Churchill, Manitoba which reached as far north as 64 degrees latitude. Further testing and operational use by CHS during the 1998 navigation season demonstrated GPS·C reliability and coverage at 69 degrees north latitude.