By Spencer Elliott and Colleen Carow
New technology stemming from engineering research at Ohio University may change the way the Global Positioning System is monitored.
The GPS Anomalous Event Monitor (GAEM), developed at the Avionics Engineering Center in the Russ College of Engineering and Technology, can remotely identify, capture and analyze data from GPS satellites during signal interruptions, said Senior Research Engineer Zhen Zhu, who wrote the analyzing software for the system. The information, which otherwise would be lost, can then be relayed to GPS users.
Consistent, reliable information is crucial for the wide variety of interests that use the GPS, a satellite-based radionavigation system developed and operated by the U.S. Department of Defense. Pilots landing aircraft, engineers surveying land, and military outfits coordinating troop movements all rely on accurate GPS data. The first-of-its-kind GAEM system enables users to study and compare data relevant to them, troubleshoot satellite problems and make better use of the GPS.
The research was sponsored by the Federal Aviation Administration.
Zhu noted that, the long-term goal of the research is to develop a commercially viable system. Such a system could have several levels of capability and cost in order to serve a range of public and private interests that rely on GPS.
"We're going to provide service to all levels of users," Zhu explained. Basic users could receive an e-mail about changes in GPS performance, or those with a "Cadillac" version could constantly receive a stream of real-time data about the entire system.
Three prototype systems are already in use, at Ohio University's Gordon K. Bush airport, the FAA technical center in Atlantic City, New Jersey, and at the Memphis International Airport.
The monitoring technology was developed from research into GPS software-defined radios by Senior Research Engineer Sanjeev Gunawardena when he was completing his dissertation at the Russ College. According to Gunawardena, while all the other GPS monitors use traditional receiver technology, the GAEM is the first known monitor based on instrumentation-quality software defined radio technology. The technology allows researchers to monitor GPS signals in unprecedented ways, and allows data records of anomalous events to be archived for future reference.
While the project is currently focused on capturing, analyzing and disseminating information about GPS disruptions, the system may also have applications for predicting when such disruptions are likely to occur.
"A great number of events are repeatable," Zhu said. The GAEM will provide a record of the disruption events, allowing researchers to look for patterns, identify possible causes and potentially forecast future problems with the GPS.