ARLINGTON, Va. -- An Ohio State University research team has developed very efficient approaches vital to the success of global navigation satellite systems.
Air Force Office of Scientific Research-funded scientist, Dr. Inder J. Gupta, led the team and conducted both the theoretical and practical work that has enabled techniques to estimate and lessen antenna-caused biases in GPS (Global Positioning System) receivers equipped with anti-jam antennas or adaptive antennas.
Dr. Arje Nachman, AFOSR Program Manager for this effort noted, "This work has direct impact on Joint Precision Approach and Landing (JPALS) program, AFRL/RY's Worldwide Accurate Sensor Positioning System (WASPS) program or any other program that requires precise navigation and/or geo-location."
Military GPS receivers use adaptive antennas to operate in hostile electromagnetic environments (jamming). An adaptive antenna adjusts its pattern in real-time to minimize the effect of jamming on the GPS receiver. This is accomplished by steering the radiation pattern minima in the jammer directions while maintaining the desired response in the GPS satellite direction.
Dr. Gupta noted, "GPS has become increasingly significant to the military for precision navigation and timing and is the most widely used source to obtain this information. A GPS receiver determines its locations by measuring the distance from multiple GPS satellites in view The approaches we have developed are very significant because previously the receiver's antenna and associated electronics introduced distortion into the satellite signals that resulted in biases in the distance measurements and affected the accuracy of position and time solution."
Dr. Gupta has also designed and built a new ground plane for the testing of the antennas and studied the effects of antenna elements on the performance of GPS anti-jam antennas.
Recently, Dr. Gupta was awarded an Institute of Navigation Fellowship with the citation, "For contributions to the theory and development of adaptive antennas for satellite navigation."