Abstract: An airborne collision avoidance system includes a receiver stage constructed and arranged to detect (a) at a first radio frequency, first interrogation signals, and first collision resolution advisory (RA) signals transmitted from other nearby aircraft, and (b) at a second radio frequency, first acquisition signals including position information with respect to the nearby aircraft, and first reply signals from the nearby aircraft. A transmitter stage is constructed to produce (a) at the first radio frequency, second interrogation signals and second collision RA signals, and (b) at the second radio frequency, second acquisition signals including position information with respect to the given aircraft, and second reply signals from the given aircraft in response to the first interrogation signals. Tracking and collision avoidance information derived by a system processor from the detected first acquisition and first RA signals is shown on a cockpit display.

Abstract: An airborne collision avoidance system includes a receiver stage constructed and arranged to detect (a) at a first radio frequency, first interrogation signals, and first collision resolution advisory (RA) signals transmitted from other nearby aircraft, and (b) at a second radio frequency, first acquisition signals including position information with respect to the nearby aircraft, and first reply signals from the nearby aircraft. A transmitter stage is constructed to produce (a) at the first radio frequency, second interrogation signals and second collision RA signals, and (b) at the second radio frequency, second acquisition signals including position information with respect to the given aircraft, and second reply signals from the given aircraft in response to the first interrogation signals. Tracking and collision avoidance information derived by a system processor from the detected first acquisition and first RA signals is shown on a cockpit display.

Abstract: A system for locating and identifying aircraft while on an airport. Each aircraft has an IFF transponder which is interrogated from on board the aircraft to produce replies at a slower rate than normal interrogation rates. A plurality of receiving stations at different locations about the airport measure the time of arrival of the replies and decode the replies. The time of arrival information is forwarded to a central receiving station along with the decode reply data. Using conventional correlation techniques, the location of each aircraft is established through the time of arrival information as well as the identity of the aircraft from the decoded reply data.