Abstract: An algorithm for improved tracking of Air Traffic Control Radar Beacon System transponders is disclosed. The algorithm can be combined with a system that includes an interrogator which transmits an interrogation signal to an associated vehicle transponder at a first frequency, preferably 1030 MHZ in accordance with FAA regulations, and a receiver array which receives the transponder reply signal transmitted by the transponder at a second frequency, preferably 1090 MHZ in accordance with FAA regulations. An angle of arrival processor calculates an angle of the received reply signal, and a position processor calculates the vehicle position based on at least the received angle data.

Abstract: An algorithm for improved tracking of Air Traffic Control Radar Beacon System transponders is disclosed. The algorithm can be combined with a system that includes an interrogator which transmits an interrogation signal to an associated vehicle transponder at a first frequency, preferably 1030 MHZ in accordance with FAA regulations, and a receiver array which receives the transponder reply signal transmitted by the transponder at a second frequency, preferably 1090 MHZ in accordance with FAA regulations. An angle of arrival processor calculates an angle of the received reply signal, and a position processor calculates the vehicle position based on at least the received angle data.

Abstract: A ground-based, precision aircraft landing system provides CAT I precision approach and landing guidance. The aircraft elevation position is determined by measuring differential carrier phase and time-of-arrival of the aircraft ATCRBS transponder reply. The transponder reply is received at a plurality of sensor antenna locations where it is then conveyed to a sensor, demodulated and digitized. The data is transmitted to a central processor where calibration and multipath corrections are applied. Aircraft transponder diversity antenna switching is isolated from the jitter and colored noise of transponder reply multipath by correlating differential phase jumps measured between separate sensor antennas. An estimate of the diversity antenna separation is maintained by Kalman filter processing; the estimated separation is used to correct the differential phase measurement data of aircraft elevation.