Code carrier divergence monitoring for dual-frequency GBAS
Code carrier divergence monitoring for dual-frequency GBAS
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DOI：
10.1007/s10291-016-0567-4
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发表时间：
2017-04-01
期刊：
影响因子：
4.9
通讯作者：
Macabiau, Christophe
中科院分区：
文献类型：
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作者：
Jiang, Yiping;Milner, Carl;Macabiau, Christophe
地基增强系统（GBAS）包括一个地面监视器，用于防止卫星有效载荷产生的码载波发散（CCD）故障。目前的单频GBAS解决方案被称为GBAS方法服务类型（GAST）C和D，分别支持I类和II/III类精度方法，两者都使用这种监测器，但已经注意到，由于标称电离层误差，测试度量受到非高斯尾部的影响。据观察，在低海拔地区看到的电离层延迟可能触发与有效载荷故障无法区分的警报，从而影响GAST-D的连续性和可用性。未来的GAST-F概念旨在使用多频率测量满足第二/第三类精确方法，使拟议的CCD监测器不受电离层影响。为了解决整个威胁空间，需要结合三个无电离层统计数据来形成测试度量。该测试度量的特征在于通过经验多频数据分析和理论推导的组合，导致由标准差0.0017、0.0050和0.0046 m/s组成的近似对角协方差矩阵，而当前单频GAST-D设计的标准差为0.00399 m/s。结果从广泛的模拟评估显示器的完整性性能，然后提供显示上级性能的现有设计。拟议的GAST-F监测器检测到的分歧小于一半的GAST-D的大小，与相同的概率错过检测。在GAST-F概念下，飞机可能在无电离层平滑模式下运行，这导致发散对大部分威胁空间的影响膨胀，并降低所有潜在CCD监视器的性能。它示出了一个更长的延迟是需要一个平滑的测距测量到解决方案中的纳入。最坏情况的故障模式需要比电流值50 s延迟132 s。
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 current single-frequency GBAS solutions known as GBAS approach service types (GAST) C and D which support Category I and Category II/III precision approaches, respectively, both utilize this monitor, but it has been noted that the test metric is subject to non-Gaussian tails as a result of nominal ionospheric errors. It has been observed that the ionospheric delay seen at low elevations can trigger alarms which are not distinguishable from the payload fault and thus impact the continuity and availability of GAST-D. The future GAST-F concept is designed to meet Category II/III precision approach using multi-frequency measurements which allows the CCD monitor proposed to be free of ionospheric influence. In order to address the full threat space, the combination of three ionospheric-free statistics is needed to form the test metric. This test metric is characterized through a combination of empirical multi-frequency data analysis and theoretical derivations leading to an approximately diagonal covariance matrix consisting of standard deviations 0.0017, 0.0050 and 0.0046 m/s, compared to 0.00399 m/s for the current single-frequency GAST-D design. Results from extensive simulations assessing the monitor's integrity performance are then provided which show superior performance to the existing design. The proposed GAST-F monitor detects a divergence less than half the size of the GAST-D one, with the same probability of missed detection. Under the GAST-F concept, the aircraft may be operating in ionospheric-free smoothing mode which leads to inflation of the divergence impacts for much of the threat space and degrades the performance of all potential CCD monitors. It is shown that a longer delay is required for the incorporation of a smoothed ranging measurement into the solution. The worst-case fault mode requires a delay of 132 s over the current value 50 s.