Research On LPV Approach Performance Based On WAAS

The Satellite Based Augmentation System?SBAS?is an enhanced system of Global Navigation Satellite Systems?GNSS?,with the United States,Europe,Russia,Japan and India all building their own SBAS.Among them,the United States'Wide Area Augmentation System?WAAS?plays a leading role in technology.WAAS is designed to provide seamless navigation from route to non-precision approach for the aircraft in WAAS service area,up to Localizer Performance with Vertical guidance?LPV?-200 approach.A total of nearly 4,000LPV/LPV-200 approach procedures were issued within the WAAS service area to guide the aircraft to a safer approach on the runway without Instrument Landing System?ILS?.1.The operation principle of WAAS system is introduced,and WAAS message is elaborated.The positioning error source in WAAS system is analyzed,and the correction algorithm is given in combination with WAAS message solving.2.Combined with the solution of WAAS message,the algorithm of accuracy and integrity parameters is elaborated.The accuracy and integrity parameters of WAAS system are analyzed with the measured data.Taking the 24h data of a single-point monitoring station as an example,the comparison of GPS and WAAS positioning accuracy is given,and the changes of?²_flt,?²_UIRE and?²_tropo values in integrity protection level are given.The measured data is extended to a total of 44 stations for 4 days,and the accuracy and integrity of the WAAS service area are analyzed.Based on the algorithm,a WAAS performance analysis utility software is developed.3.The development and application of LPV/LPV-200 approach procedure is analyzed.The similarities and differences between LPV/LPV-200 approach and ILS approach are given,and the availability coverage of LPV approach is solved with measured data.The simulation experiment system is built to simulate the normal situation,1 satellite fault and 2 satellite faults when the aircraft carried out the LPV-200 approach,and the accuracy and integrity parameters in the approach process are solved.The results show that normal conditions and a satellite failure can support the aircraft to complete the LPV-200 approach.The performance parameters based on the monitoring data are in good agreement with the statistics published by the Federal Aviation Administration?FAA?and the National Satellite Test Bed?NSTB?.The research on the approach performance of WAAS-based LPV approach can provide theoretical and experimental support for the performance evaluation of LPV approach operation based on the construction of the BeiDou Satellite Based Augmentation System?BDSBAS?.