A Differential Global Positioning System for Determining Time Space Position Information in Support of Aircraft Noise Certification

摘要

Federal Aviation Regulation (FAR) Part 36, Noise Standards: Aircraft Type and Airworthiness Certification, requires that measured aircraft noise certification data be corrected to a nominal reference-day condition. This correction process which can be quite rigorous is typically done for sequential 1/2-second acoustic data records measured for a given aircraft noise certification event. Consequently, the process requires precise time-space-position-information (TSPI) for each acoustic data record within each event. Traditionally, noise certification applicants have used optical positioning systems such as still cameras and video cameras, radar, or in rare instances, laser tracking systems. The accuracy of these systems is typically on the order of 10 to 20 ft., although the accuracy of laser tracking systems can be much better. In addition, many of these traditional systems only provide TSPI data over a relatively limited time interval in the vicinity of aircraft overhead, thus requiring extrapolation of TSPI data to sufficiently define aircraft position for each acoustic data record within each certification event. With the advent of differentially corrected global positioning systems (dGPS), the accuracy and limitations associated with traditional TSPI systems are easily overcome. This paper describes a dGPS TSPI system developed by the U.S. Department of Transportation (DOT) Volpe Center Acoustics Facility (Volpe). The paper includes descriptions of both the hardware and software components of the system. It also details the static and dynamic system performance.