Wang Zhipeng, Wang Shujing, Zhu Yanbo, Xin Pumin
National Key Laboratory of CNS/ATM, School of Electronic and Information Engineering, Beihang University, Beijing 100191,China.
Sensors (Basel). 2017 Oct 11;17(10):2313. doi: 10.3390/s17102313.
Ionospheric delay is one of the largest and most variable sources of error for Ground-Based Augmentation System (GBAS) users because inospheric activity is unpredictable. Under normal conditions, GBAS eliminates ionospheric delays, but during extreme ionospheric storms, GBAS users and GBAS ground facilities may experience different ionospheric delays, leading to considerable differential errors and threatening the safety of users. Therefore, ionospheric monitoring and assessment are important parts of GBAS integrity monitoring. To study the effects of the ionosphere on the GBAS of Guangdong Province, China, GPS data collected from 65 reference stations were processed using the improved "Simple Truth" algorithm. In addition, the ionospheric characteristics of Guangdong Province were calculated and an ionospheric threat model was established. Finally, we evaluated the influence of the standard deviation and maximum ionospheric gradient on GBAS. The results show that, under normal ionospheric conditions, the vertical protection level of GBAS was increased by 0.8 m for the largest over bound σ v i g (sigma of vertical ionospheric gradient), and in the case of the maximum ionospheric gradient conditions, the differential correction error may reach 5 m. From an airworthiness perspective, when the satellite is at a low elevation, this interference does not cause airworthiness risks, but when the satellite is at a high elevation, this interference can cause airworthiness risks.
电离层延迟是地基增强系统（GBAS）用户误差的最大且变化最大的来源之一，因为电离层活动不可预测。在正常情况下，GBAS可消除电离层延迟，但在极端电离层风暴期间，GBAS用户和GBAS地面设施可能会经历不同的电离层延迟，从而导致相当大的差分误差并威胁用户安全。因此，电离层监测和评估是GBAS完整性监测的重要组成部分。为研究电离层对中国广东省GBAS的影响，使用改进的“简单真值”算法对从65个参考站收集到的GPS数据进行了处理。此外，计算了广东省的电离层特征并建立了电离层威胁模型。最后，评估了标准偏差和最大电离层梯度对GBAS的影响。结果表明，在正常电离层条件下，对于最大超限垂直电离层梯度σvig，GBAS垂直保护水平提高了0.8米，而在最大电离层梯度条件下，差分校正误差可能达到5米。从适航角度来看，当卫星处于低仰角时，这种干扰不会造成适航风险，但当卫星处于高仰角时，这种干扰会造成适航风险。
