Demonstration of a P(Y)-Code Differential GPS Precision Approach System

Abstract

Honeywell and the United States Air Force (USAF) recently completed the demonstration of a P(Y)-code differential precision approach system. The demonstration was based on differential carrier-smoothed P(Y)-code GPS measurements provided from an RTCA DO-217 compliant ground reference station. The flight path deviations were obtained using standard instrument landing system (ILS) conventions and predefined approach data. The aircraft installation included two GPS receiver types, integrated into an inertial reference system. Both hybrid and autonomous solutions were evaluated in the demonstration. The airborne equipment utilized 5- and 12-channel GPS receivers obtained from two vendors. This paper evaluates the performance of both integrated and autonomous architectures. Honeywell modified the SLS-2000 ground reference station to use P(Y)-code measurements from a Trimble “Force-12” GPS receiver. The objective of this paper is to evaluate the ability of the military aircraft to perform precision approach operations using differential GPS (DGPS) signals.