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SBAS DFMC service for road transport: positioning and integrity monitoring with a new weighting model
Journal of Geodesy ( IF 4.4 ) Pub Date : 2021-02-22 , DOI: 10.1007/s00190-021-01474-z
K. Wang , A. El-Mowafy , C. Rizos , J. Wang

In 2017, the new generation satellite-based augmentation system (SBAS) test-bed was initiated by Australia and New Zealand, which supports the dual-frequency multi-constellation (DFMC) positioning with both GPS and Galileo signals. This new SBAS DFMC service allows the elimination of the first-order term of the ionospheric delays, and extends the service area to the entire footprint of the geostationary satellite. In addition to the satellite clock and orbital corrections, the integrity information is also broadcast by the SBAS satellite to users, so that protection levels can be computed to bound the positioning errors with a pre-defined probability of hazardous misleading information. Different from the aeronautical applications, the ground-based applications for road transport may suffer from new problems in different measurement environments, e.g. complicated multipath behaviours and frequent filter re-initialisations during positioning in urban areas. A new weighting model allowing different impacts of the elevation angles, the signal-to-noise-ratios and the smoothing time after re-initialisations is proposed and compared with the traditional elevation-dependent weighting model. The model is applied to the carrier-smoothed code measurements in different environments, i.e., the open-sky scenario, the suburban scenario and the urban scenario. It is found that the new weighting model effectively de-weights the large residuals in the suburban and the urban scenarios, where the mean values and the standard deviations of the overbounding excess-mass cumulative density function can be significantly reduced for the combined weighted noise and multipath. Using 1 Hz GNSS observations measured in these three measurement environments, the horizontal positioning errors (HPEs) and the horizontal protection levels (HPLs) are computed for different filter smoothing windows. Applying the new weighting model, significant reduction can be observed in the mean HPLs in the suburban and urban scenarios. Among them, the reduction in the HPLs have reached about 35–40% in the suburban scenario. The mean absolute HPEs are also reduced by about 10% in the urban scenario. However, when under the open-sky scenario, the traditional elevation-dependent weighting model is sufficient for the positioning and integrity monitoring using the SBAS DFMC service.



中文翻译:

SBAS DFMC公路运输服务:采用新的加权模型进行定位和完整性监控

2017年,澳大利亚和新西兰启动了新一代基于卫星的增强系统(SBAS)测试平台,该平台支持GPS和Galileo信号的双频多星座(DFMC)定位。这项新的SBAS DFMC服务可以消除电离层延迟的一阶项,并将服务区域扩展到对地静止卫星的整个足迹。除了卫星时钟和轨道校正之外,SBAS卫星还向用户广播完整性信息,因此可以计算保护等级以限制定位错误,并具有危险的误导性信息的预定概率。与航空应用不同,陆路运输的地面应用可能会在不同的测量环境中遭受新的问题,例如,在城市地区定位期间,复杂的多径行为和频繁的滤波器重新初始化。提出了一种新的加权模型,该模型允许对仰角,信噪比和重新初始化后的平滑时间产生不同的影响,并将其与传统的依赖于海拔的加权模型进行比较。该模型适用于不同环境(即,露天场景,郊区场景和城市场景)中载波平滑代码的测量。结果发现,新的加权模型可以有效地对郊区和城市场景中的大残差进行去加权,对于合并的加权噪声和噪声,可以显着降低超量质量累积密度函数的平均值和标准偏差。多路径。使用在这三个测量环境中测量的1 Hz GNSS观测值,可以为不同的滤波器平滑窗口计算水平定位误差(HPE)和水平保护水平(HPL)。应用新的加权模型,可以观察到郊区和城市场景中的平均HPL显着降低。其中,在郊区情况下,HPL的减少已达到约35–40%。在城市场景中,平均绝对HPE也降低了约10%。但是,在开阔天空的情况下,传统的基于海拔的加权模型对于使用SBAS DFMC服务的定位和完整性监视已足够。针对不同的滤波器平滑窗口计算水平定位误差(HPE)和水平保护等级(HPL)。应用新的加权模型,可以观察到郊区和城市场景中的平均HPL显着降低。其中,在郊区情况下,HPL的减少已达到约35–40%。在城市场景中,平均绝对HPE也降低了约10%。但是,在开阔天空的情况下,传统的基于海拔的加权模型对于使用SBAS DFMC服务进行的定位和完整性监视已足够。针对不同的滤波器平滑窗口计算水平定位误差(HPE)和水平保护等级(HPL)。应用新的加权模型,可以观察到郊区和城市场景中的平均HPL显着降低。其中,在郊区情况下,HPL的减少已达到约35–40%。在城市场景中,平均绝对HPE也降低了约10%。但是,在开阔天空的情况下,传统的基于海拔的加权模型对于使用SBAS DFMC服务进行的定位和完整性监视已足够。在城市场景中,平均绝对HPE也减少了约10%。但是,在开阔天空的情况下,传统的基于海拔的加权模型对于使用SBAS DFMC服务进行的定位和完整性监视已足够。在城市场景中,平均绝对HPE也降低了约10%。但是,在开阔天空的情况下,传统的基于海拔的加权模型对于使用SBAS DFMC服务的定位和完整性监视已足够。

更新日期:2021-02-23
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