A Differential Global Positioning System forDetermining Time Space Position Informationin Support of Aircraft Noise Certification

摘要

Federal Aviation Regulation (FAR) Part 36, ?NoisernStandards: Aircraft Type and AirworthinessrnCertification,? requires that measured aircraft noiserncertification data be corrected to a nominal reference-dayrncondition. This correction process which can be quiternrigorous is typically done for sequential ?-secondrnacoustic data records measured for a given aircraft noiserncertification event. Consequently, the process requiresrnprecise time-space-position-information (TSPI) for eachrnacoustic data record within each event. Traditionally,rnnoise certification applicants have used opticalrnpositioning systems such as still cameras and video cameras, radar, or in rare instances, laser trackingrnsystems. The accuracy of these systems is typically onrnthe order of 10 to 20 ft., although the accuracy of laserrntracking systems can be much better. In addition, manyrnof these traditional systems only provide TSPI data over arnrelatively limited time interval in the vicinity of aircraftrnoverhead, thus requiring extrapolation of TSPI data tornsufficiently define aircraft position for each acoustic datarnrecord within each certification event. With the advent ofrndifferentially corrected global positioning systemsrn(dGPS), the accuracy and limitations associated withrntraditional TSPI systems are easily overcome. This paperrndescribes a dGPS TSPI system developed by the U.S.rnDepartment of Transportation (DOT) Volpe CenterrnAcoustics Facility (Volpe). The paper includesrndescriptions of both the hardware and softwarerncomponents of the system. It also details the static andrndynamic system performance.