Prediction and analysis of GBAS integrity monitoring availability at LinZhi airport

Prediction and analysis of GBAS integrity monitoring is important, especially at the airports where a GBAS station it to be installed. Based on existing standard documents and published research, we present a software tool for GBAS availability prediction. Simulations have been conducted that include single point, single approach path, and multiple repetitions of a same approach path in order to analyze the availability of GNSS signal integrity monitoring with a GBAS at LinZhi airport. The results show that the long-term 24-h service availability figure at two typical single points along the approach path for GBAS Approach Service Type C (GAST C) is above 99.999 % for each point, and for GBAS Approach Service Type D (GAST D) at three typical single points, it is lower than 99.8 % for each point. The unavailability percentage over a 24-h period is 0.76 and 2.40 % for GAST C and GAST D, respectively. The results of sensitivity tests show that the impact of the mask angle and the latitude on the GBAS availability at LinZhi airport are more important than that of the constellation. Our conclusions could also be of interest for the implementation of GBAS stations at other plateau airports.     

GBAS testbed development in Taiwan with a prototype GPS/GBAS receiver

In this paper, we present the development of a local area differential GPS testbed of the ground-based augmentation system (GBAS) as the future airport navigation facility in the Taipei Flight Information Region (FIR) in Taiwan. The testbed is mainly a GBAS ground facility, which consists of a ground station, three GBAS receivers, and a VDL (VHF data link) broadcast antenna. We also present an airborne GPS/GBAS prototype receiver in this paper. The airborne subsystem (a GPS/GBAS receiver) receives the correction messages from the ground subsystem to perform a differential GPS (DGPS) positioning. In order to provide an ILS-look-alike approach and landing, the output messages of the airborne receiver are packed in an ARINC 429 format. The proposed airborne system has a software-based global navigation satellite system (GNSS) receiver structure.     

北斗地基增强系统数据通信综述

数据通信是实现北斗地基增强系统高精度导航、定位不可或缺的部分,在系统中起着关键作用。首先探讨了北斗地基增强系统参考站与数据中心进行数据通信所用到的TCP／IP和RS232接入模式,其次,针对用户与数据中心的数据通信,分析了NMEA0183信息、NRTIP协议和RTCM数据,并阐述了RTCM3.2较以前版本的改进内容。      

Code carrier divergence monitoring for dual-frequency GBAS

GPS Solutions - The ground-based augmentation system (GBAS) includes a ground monitor designed to protect against a code carrier divergence (CCD) fault originating from the satellite payload. The...     

陆基增强系统在无人机进近着陆中的性能分析

针对大型无人机与民用客机在同一空域环境中运行,使用传统的单点定位方法,定位精度低,可靠性差,不能满足大型无人机进近着陆需求的问题,提出了一种提高大型无人机进近着陆过程中的定位精度的方法。利用陆基增强系统,为传统的伪距观测提供差分修正,使大型无人机在进近着陆过程中获得更精确的高程信息。实验结果表明,相比于传统的单点定位方法,利用陆基增强系统进行无人机进近下降着陆,在很大程度上提高了无人机的高程定位精度,确保了无人机在进近着陆过程中的运行安全。研究结果为无人机与民用客机的联合运行以及未来"空管一体化"标准的制定提供了重要理论支撑。     

Ionospheric delay gradient model for GBAS in the Asia-Pacific region

GPS Solutions - We investigated characteristics of anomalous spatial gradients in ionospheric delay on GNSS signals in the Asia-Pacific (APAC) low-magnetic latitude region in the context of the...     

Approach service type D evaluation of the DLR GBAS testbed

Ground-based augmentation systems (GBAS) for satellite navigation are intended to replace the instrument landing system for precision approach of aircraft into an airport in the near future. Here, we show an evaluation of data collected during flight trials with the GBAS testbed of the German aerospace center with respect to requirements for the GBAS approach service type D. This service will permit approach and landing down to the zero visibility conditions of category IIIc approaches. We show output of all airborne monitors and the results of an integrity analysis. During all flight trials, the system performed within the required criteria for integrity, continuity, and availability.     

局部电离层异常对局域增强系统的影响及其监测方法

传统的局域增强系统认为影响用户和基准站伪距的观测误差是基本相同的,因而可通过伪距差分技术将这部分误差消除,但为发生电离层风暴时,叠加在基准站和用户伪距上的电离层延迟误差将会不同,因此会影响定位结果。本文利用CCDMA算法和DSCMA算法对电离层异常进行探测,并对伪距差分技术进行改进。仿真结果显示,这种方法可有效减小局部电离层异常对CATⅢ飞行阶段的威胁。     

BDS/GPS双系统组合GBAS性能评估

随着北斗卫星导航系统(BDS)全球组网进程的推进,BDS/GPS组合导航成为提高导航性能的重要方法,同时地基增强系统(GBAS)作为实现精密导航的新一代导航方式是当前研究的热点。本文通过推导BDS/GPS双系统组合GBAS数学模型,分别对BDS、GPS独立作为GBAS导航源及BDS/GPS组合导航作为GBAS导航源时系统的精度因子(DOP)、垂直保护级(VPL)性能进行了对比分析,对比验证了应用各系统时GBAS性能的差异。结果表明,基于BDS与GPS的GBAS性能接近,且互有优势;BDS/GPS组合GBAS性能优于各单系统性能。     

伪卫星辅助下的北斗GBAS完好性增强技术研究

根据机场实施精密导航技术（RNP）的要求,国际民航组织（ICAO）提出地基增强系统（GBAS）,GBAS必将成为未来发展的必然趋势。但是在复杂的机场环境下,卫星信号易受外界影响和干扰,连续性不足,进而影响GBAS系统完好性性能的实施。因此,本文提出了伪卫星与北斗卫星联合定位增强GBAS的方法,并从加入伪卫星后的精度因子（DOP）、多参考一致性检测（MRCC）、完好性等方面进行了对比仿真分析。仿真结果表明,增加伪卫星后的系统精度因子得到了明显改善（PDOP小于3）,同时提高了完好性性能,能够为复杂环境下的机场提供GBAS CAT Ⅱ类及以上等级的精密进近服务。     

载波相位平滑时间常数对GBAS精度增强的影响

陆基增强系统(GBAS)是利用载波相位平滑伪距差分修正实现对导航辅助定位的. 其中,平滑时间常数是影响载波相位平滑伪距精度的关键参数. 本文分析研究了不同平滑时间下电离层时间梯度和空间梯度对Hatch滤波的影响. 在结合电离层时空梯度和多径效应引起的滤波总误差方差的基础上,推导出自适应的最优平滑时间常数. 分别对GBAS静态和动态两种环境下的定位误差进行实验,实验结果表明,采用本文推导出的自适应平滑时间常数降低了GBAS伪距测量误差,从而使定位精度得到增强.      

SENSOR: a tool for the simulation of hyperspectral remote sensing systems

The consistent end-to-end simulation of airborne and spaceborne earth remote sensing systems is an important task, and sometimes the only way for the adaptation and optimisation of a sensor and its observation conditions, the choice and test of algorithms for data processing, error estimation and the evaluation of the capabilities of the whole sensor system.The presented software simulator SENSOR (Software Environment for the Simulation of Optical Remote sensing systems) includes a full model of the sensor hardware, the observed scene, and the atmosphere in between. The simulator consists of three parts. The first part describes the geometrical relations between scene, sun, and the remote sensing system using a ray-tracing algorithm. The second part of the simulation environment considers the radiometry. It calculates the at-sensor radiance using a pre-calculated multidimensional lookup-table taking the atmospheric influence on the radiation into account. The third part consists of an optical and an electronic sensor model for the generation of digital images. Using SENSOR for an optimisation requires the additional application of task-specific data processing algorithms.The principle of the end-to-end-simulation approach is explained, all relevant concepts of SENSOR are discussed, and first examples of its use are given. The verification of SENSOR is demonstrated. This work is closely related to the Airborne PRISM Experiment (APEX), an airborne imaging spectrometer funded by the European Space Agency.     

Flight test evaluation of ILS and GBAS performance at Gimpo International Airport

We address the differences in the ways the Instrument Landing System (ILS) and Ground-Based Augmentation System (GBAS) offer approach guidance, and their principles and methods. We perform comparative analysis of the accuracy of deviation between the GBAS Landing System (GLS) and ILS by means of flight tests, using the flight inspection aircraft at Gimpo International Airport. Our results show that the ILS deviation error increases as the distance between the threshold of runway and the aircraft increases; on the other hand, the GLS deviation error is stable, within the range of ±0.5 to ±2 m lateral and vertical deviation, respectively. We also analyze the alignment accuracy of the ILS and GLS based on the evaluation criteria of Category I of the Federal Aviation Administration, and our analysis results confirm that both systems satisfy the requirements (lateral: ±0.1°, vertical: ±0.05°).     

遥感与GIS技术在西部支线机场建设中的初步应用研究——以云南腾冲机场为例

本文就西部支线机场建设的不利因素,提出了将遥感和GIS技术的优势充分应用于机场建设前期选址决策中,并以腾冲驼峰国际机场建设为例,探讨应用遥感技术,制作遥感图像三维可视化,为决策者提供直观的实地三维影像图;利用地理信息系统的空间分析功能,进行坡面、坡度和净空分析,可以为机场选址、布线等方面提供决策依据。遥感和GIS技术的综合应用对西部支线机场现代化建设创优工程提出了一定思路和技术方法。     

机场净空GIS快速评定方法研究

本文通过对机场净空规格进行分析,建立了机场净空区障碍物限制面的数学模型。在此数学模型的基础上使用ArcGIS、AutoCAD软件建立净空限制面三角网高程模型,并进行三维显示以及净空评定,为使用地理信息系统进行净空管理创造条件。     

一种基于跑道检测的机场识别方法

遥感图像中机场的识别以检测跑道为主。用改进的Hough变换方法对机场图像的边缘检测图进行计算,提取出机场跑道对应的平行直线对,然后计算跑道中心线所对应的像素点,以它们为种子点进行区域生长,识别主要机场结构。     

Integrity monitoring algorithms for airport surface movement

Navigation algorithms are proposed for carrier phase ambiguity integrity monitoring to support aircraft surface movement. The enhanced integrity monitoring algorithm addresses the very stringent integrity requirements for surface movement by the use of multiple test statistics and a group separation concept for single and multiple failure detection and exclusion. The algorithms are subject to a detailed performance characterization for precision approaches and airport surface movement, using simulations as well as static and dynamic field trials, taking into account operational specificities, such as multipath and potential decorrelations between the reference station and aircraft due to ionospheric anomalies. Results show that the proposed algorithms have the potential to satisfy airport surface movement requirements if the ionospheric anomalies are monitored using a special ground-based network.     

高填方机场边坡变形监测新方法

分析高填方机场边坡变形监测传统方法的不足,提出应用单台全站仪的自由设站变形监测方法,应用基于光束法平差的多测站观测值统一解算的数据处理方法,并在实际工程中与GPS方法进行比对,论证该方法的正确性和优越性,为今后解决类似工程问题提供借鉴.