CYCLE AMBIGUITY ESTIMATION FOR AIRCRAFT PRECISION LANDING USING THE GLOBAL POSITIONING SYSTEM

Measurements of the Global Positioning System carrier phase can provid e the basis for the highest level of satellite-based navigation perfor mance. In particular, the potential exists to exceed even the stringen t navigation requirements for aircraft precision approach and landing. The principal difficulty in this use of carrier phase, however lies i n the real-time, high-integrity resolution of the unknown integer cycl e ambiguities. A new methodology is introduced, using carrier phase me asurements from ground-based pseudolites, for explicit estimation of t he cycle ambiguities. The mathematical basis of the new approach is de tailed, and high-speed nonlinear information smoothing algorithms suit able for real-time airborne execution are derived. Extensive flight-te st data, including the results of automatic landings of a Boeing 737 a ircraft, are presented as experimental validation of algorithm perform ance.