A Study to determine the Future of DGPS in Canada

Jean Delisle and Caroline Huot

Abstract:	Mariners navigating in Canadian waters have access to a Ground-Based Augmentation System (GBAS) providing differential corrections and integrity monitoring of the Global Positioning System (GPS) in order to improve their position accuracy and trust in position. Since 1996, the Canadian Coast Guard (CCG) has been providing a GBAS in the form of a Differential GPS broadcast service. This service consists of 19 land-based DGPS sites installed across Canada. The service is only provided south of latitude 60°North. Currently, six United States Coast Guard (USCG) DGPS stations and one Canadian station provide a seamless DGPS service to mariners on the Great Lakes. This service will soon be unavailable with the US gradual decommissioning of its Nationwide DGPS (NDGPS) sites. USCG Great Lakes DGPS stations will be decommissioned in July 2020 creating an immediate challenge for the CCG to provide an augmentation capability in this area. Prior to initiating a DGPS recapitalization program, CCG is evaluating nine options for both the future of the DGPS service and its DGPS network. Options range from doing nothing, to a replacement with a like-for-like service, to the utilization of alternate methods of providing GNSS corrections. The underlying objective of this study is to determine the best way forward for the Canadian DGPS service provider – CCG – and for Canadian DGPS network users given the impending demise of the North American DGPS service and the obsolescence of the Canadian DGPS network. These deliberations are informed by the need to ensure the continuing safety of mariners while maximizing the value of public funding expended in realizing the selected solution. This presentation describes the evaluation undertaken on behalf of the CCG to assess the technical performance criteria, technology availability, regulation compliance, coverage and cost efficiency of each option. A list of recommendations addresses both the immediate Great Lakes coverage issue as well as the best short-term options for CCG (DGPS service and infrastructure) and the interests of DGPS users. As well, long-term options are identified reflecting foreseeable improvements related to the GNSS signal and GNSS receivers. In addition, given the focus on increasing Arctic maritime traffic, consideration of DGPS alternatives includes a review of performance both north and south of latitude 60° North. One of the options included in this study builds upon a paper on WAAS modeling validated with an actual data collection across Canada presented by Serco Inc. and J. Delisle at ION ITM 2019. The outcomes of this study will inform the CCG DGPS replacement strategy and provide a roadmap for the adoption and implementation of recommendations. Maritime authorities that have decided to end their DGPS service have generally neither provided a detailed rationalization of their decision to decommission DGPS nor a detailed rationalization for the choice of their DGPS alternative. Alternatively, this study provides a detailed explanation of the considerations that led to each of the recommendations while taking into account the challenges associated with providing navigation services in a large country bordered by three oceans including the Arctic. A significant number of maritime authorities around the world are operating aging marine radiobeacon DGPS infrastructure and, as is the case in Canada, are investigating potential alternatives. CCG wishes to share the results of its work in order to stimulate dialogue and debate on DGPS alternatives given that other maritime authorities have similar concerns and interests with regards to the future of their DGPS service and their DGPS infrastructure.
Published in:	Proceedings of the 33rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2020) September 21 - 25, 2020
Pages:	729 - 746
Cite this article:	Delisle, Jean, Huot, Caroline, "A Study to determine the Future of DGPS in Canada," Proceedings of the 33rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2020), September 2020, pp. 729-746. https://doi.org/10.33012/2020.17722
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