Automatic dependent surveillance air navigation system

Abstract

An automatic dependent surveillance (ADS) system for tracking aircraft includes a GPS navigation receiver for determining the position of an aircraft, a Mode S transponder for transmitting the position of the aircraft, and a Mode S receiving station for receiving the aircraft's position and for determining the position of the transmitting aircraft relative to other aircraft and the ground. The Mode S position information is broadcast as a squitter on a random time basis having a present average transmission rate, or in response to an interrogation signal from a Mode S receiving station. The Mode S receiver can be another aircraft, an en route ground station, and/or a terminal ground station. The en route ground station can include a multi-sector receiving antenna with each sector connected to a separate Mode S receiver. The terminal ground station can include an omni-directional antenna connected to a Mode S receiver. The Mode S transponder transmits a formatted message having airborne or surface position information including the type of GPS signal used to determine the aircraft's position, the latitude and longitude of the aircraft, the barometric altitude of the aircraft, the magnetic heading of the aircraft, and movement characteristics of the aircraft. The Mode S data link can convey differential GPS correction information to the aircraft.

Dependencies are inferred from the claim text.