Protecting the global positioning system

A report published by the Volpe National Transportation Systems Center titled "Vulnerability Assessment of the Transportation Infrastructure Relying on the Global Positioning System" (29 August 2001) states that the civil transportation infrastructure, seeking the increased efficiency made possible by GPS, is developing a reliance on GPS that could lead to serious consequences if the service is disrupted, and the applications are not prepared with mitigating equipment and operational procedures. The findings of the Volpe report suggest, among other things, that systems and procedures to monitor, report, and locate unintentional interference should be implemented or utilized in any application for which loss of GPS is not tolerable. This paper discussed the use of the GPS anomaly monitoring equipment suite (GAMES) to detect and report anomalies in GPS. The paper also discussed systems performance via test results and demonstrated how GAMES could be used for critical infrastructure protection. Data is presented to show the different anomalies that could occur as well as demonstrating how GAMES would handle such anomalies. GAMES give the user a real-time report on how accurate GPS is, and by using the GPS interference and navigation tool (GIANT) the user can predict the accuracy and effectiveness of GPS in the near future. The combination of these tools creates a "system" that can be used to monitor and evaluate the GPS environment and determine impacts on GPS-aided applications. Taking the application one step further, General Dynamics has developed the GPS interference location system (GELS) that ties directly to GAMES. When GAMES detects an anomaly, GILS begins to search for the interference(s) source and passes the collected data to the Web server where the location is computed and reported. This sensor will be described and test results will be presented to demonstrate the applicability and use for commercial as well as military use. By implementing GAMES, GILS, and GIANT, the question behind GPS reliability is a thing of the past, which will allow for increased use and reliance upon GPS. The knowledge gained from the development and application of these tools is one of the fundamental building blocks for this effort. This project developed a proof-of-concept that quantified the capability realized from being able to both detect and locate sources of interference during a GPS anomaly or interference event. This includes determining the benefits of interference identification for a variety of critical civil applications, and providing insights to help mitigate potential adverse impacts. The technical approaches undertaken are outlined, results-to-date presented, and recommendations discussed on how to take this project from proof-of-concept to fielded system.