Power spectral density analysis of ILS, MLS, and GPS landing guidance error data collected simultaneously aboard a general aviation aircraft

During recent flight tests at Atlantic City International Airport (ACY), a general aviation aircraft flew forty one approaches using Instrument Landing System (ILS) guidance. During each of the approaches, guidance data were recorded from the ILS and a Microwave Landing System (MLS), also available at ACY. In addition, GPS data were recorded from two narrow correlator C/A-code receivers and two dual frequency P-code receivers - one of each type receiver was on board the aircraft and one of each type was located at a surveyed ground location. In each instance, the GPS receivers shared a single antenna. GPS data from the narrow-correlator receivers are combined and post-processed using software developed by Ohio University for the OU/FAA/UPS Boeing 757 flight tests conducted in 1994/1995. Position and velocity data, the latter generated with airborne carrier-phase measurements, are developed for comparison with the ILS and MLS data. The GPS dual-frequency P-code data is and post-processed using vendor-developed The latter results are used as truth reference combined software. data for the analysis. Power spectral density plots of the navigation sensor errors are generated for each of the landing guidance systems investigated: ILS, MLS and GPS (narrow-correlator C/A-code) using GPS (dual-frequency P-code) as the truth source.