Field Data Collection to Validate the Usage of WAAS for Maritime Navigation in Canadian Waters

Abstract

Currently, mariners navigating in Canadian waters use a Ground-Based Augmentation System (GBAS) which provides differential corrections and integrity monitoring of the Global Positioning System (GPS) in order to improve their position accuracy and their trust in GPS. Since 1994, the Canadian Coast Guard (CCG) has been providing a GBAS in the form of a Differential GPS broadcast service. This service, called DGPS, consists of 19 land-based DGPS sites installed across Canada. The service is currently only provided south of latitude 60°N in collaboration with the United States Coast Guard (USCG). Before embarking on a recapitalization program of its 24-year old DGPS and given that the USCG is progressively shutting down its National Differential GPS (NDGPS) sites, the CCG is evaluating various options for the future of its own aged DGPS network. One of these options is to propose a space-based augmentation system (SBAS) called the Wide Area Augmentation System (WAAS) as an alternative to DGPS. It has emerged as a reliable and precise source of GNSS corrections. Although originally developed by the US Federal Aviation Administration (FAA) for civil aviation, WAAS has proven to be a reliable option for marine navigation as well. At first glance, with an equivalent performance, this option seems to be a workable solution. Before going further, a confirmation is needed to ensure that navigation using WAAS is safe in Canadian waters, including in the Arctic. With the continued expansion and improvement of WAAS (i.e. additional satellites, additional frequencies), the CCG is evaluating if either the current or the next generation of WAAS could be an acceptable alternative to DGPS performance in Canadian waters including in the Arctic. As part of the evaluation effort, a field data collection campaign has been undertaken to validate the usage of WAAS for maritime use. Two field data collection kits were designed and assembled and then deployed to various locations in Canada; one for use at static locations and one onboard a ship in a dynamic environment at each locale. The Canadian Precise Point Positioning service (CSRS-PPP) was used to post-process the L1/L2 data to generate ground truth positions for both the static and kinematic data collections. This paper describes the data collection kits, both hardware and software, and the receiver configurations used to collect the data. The paper also includes an analysis of the data collected at each location (accuracy, integrity, and availability) and how well this aligned with the simulation model and whether the maritime navigation requirements were met.