Augmentation of DGPS for marine navigation

Marine navigation has been revolutionised with the advent of the Global Positioning System (GPS), and the deployment of differential GPS (DGPS) systems. While most of the precision requirements for marine navigation can now be met with DGPS, the reliability of the user's position is often ignored. The question that is usually unanswered when it comes to marine navigation is “What is the typical marine blunder behaviour?” This question is answered through marine multipath simulations. The wide correlator simulations had a 99.9% blunder limit of 43 m, while the narrow correlator was only 11m. Double blunders also occurred during the simulations, however, the second blunder was less than 4 m (99.9% of the time). This suggests that significant blunders can occur.; Software simulations were conducted to evaluate the availability and reliability improvements when DGPS is augmented with the Global Navigation Satellite System (GLONASS), Galileo, geostationary satellites, and height, clock, and dynamic constraints under various masking environments. These simulations clearly demonstrated the advantage of augmenting DGPS with a second full constellation of satellites, especially under moderate to extreme masking conditions.; The augmentation improvements are irrelevant if the user's receiver does not employ a real time reliability algorithm. Thus the reliability performance of four representative marine user receivers were tested using a DGPS signal simulator. None of the receivers tested employed a reliability algorithm. Although the higher end receivers mitigated the multipath blunders, gross position errors still occurred. A simple reliability algorithm was run in post mission to demonstrate that the blunders could have been detected. It is not good enough to augment DGPS, the user's receiver must also employ a real time reliability algorithm.; The simulation and user receiver testing results were validated through a field campaign on a Canadian Coast Guard survey in Saanich Inlet, British Columbia.