A Ground Based Augmentation System Prototype for GPS and BDS

  • 葉 碩儒

Student thesis: Doctoral Thesis


Global Navigation Satellite System (GNSS) is the generic term used for all the satellite navigation systems that have a global coverage Nowadays the air traffic management system which is based on the GNSS has been used as the primary system Since the civil aviation requirements are stringent several architectures aiming at augmenting the navigation satellite system were developed In response to the problem ground based augmentation system (GBAS) is recommended by international civil aviation organization (ICAO) to increase the capacity of airports with limited airspace and has been carried out since the 1990s in the USA To develop and implement our own GBAS this work investigates the necessary algorithms Thus one objective of this work is to implement the GBAS algorithm to support terminal area navigation enhancements using augmented global positioning system (GPS) and meet the requirements of category (CAT) I precision approach and landing The hardware configuration of GBAS prototype comprises three reference stations and one pseudo-user To exclude the measurements with potential threat of integrity the reference station monitors the measurements quality and validates the navigation data from receivers Before broadcasting the corrections to user the GBAS prototype algorithm checks the consistency of correction across all reference stations Lastly the protection levels are estimated by following radio technical commission for aeronautics (RTCA) documents for evaluating the performance of the GBAS prototype The results demonstrate the capability of the GBAS prototype at National Cheng Kung University (NCKU) for CAT I approaches with 99 896% availability To prevent the civil aviation users from the HMI GBAS flags the satellites which impose potential integrity risk and excludes them from positioning In general if a GBAS user relies on fewer satellites for positioning then the resulting protection level would be higher While the protection level exceeds the alert limit the navigation availability decrease The further objectives of this work are to keep the protection level low and meet the navigation integrity requirement at the same time As the solution the additional ranging sources from BeiDou navigation satellite system (BDS) are intended to integrate into the current GBAS algorithm However since the GBAS algorithm is designed for GPS issues must be resolved before the integration For this purpose this work demonstrates the analysis for the ranging source and details the solutions for the integration At the end this work conducts the field tests to show the capability of the dual-constellation GBAS prototype and compare it to the one based on GPS only and BDS only The field test results of the developed GBAS prototype with dual-constellation showed that the GBAS with the combined use of GPS and BDS has the capability of keeping the integrity and reducing the protection level at the same time To compare with the GBAS prototype based on GPS only the results at Kaohsiung international airport show improvements in the average protection level of 24% and that of the BDS only is 52% Importantly the reduced protection level obtained from the developed dual-constellation GBAS prototype can meet the CAT I requirements with more than 99 999% availability
Date of Award2016 Aug 22
Original languageEnglish
SupervisorShau-Shiun Jan (Supervisor)

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