GAST D GBAS电离层监视算法

GAST D GBAS Ionospheric Monitoring Algorithm

GASTCGBAS传统的电离层监视方法,是码载波分歧监测(CCD)采用一阶线性时不变低通滤波器对电离层异常进行监测,被广泛用于检测GBAS电离层梯度的变化。然而,由于该方法滤波采用固定的时间常数,很难平衡GBAS系统的响应时间和定位精度。为了消除这一局限性,本文提出了GASTDGBAS两种电离层梯度异常监视方法,第一种将CCD算法优化为采用两个低通滤波器进行电离层异常监测;第二种方法为电离层梯度监视算法(IGM)通过监视基准接收机的载波相位观测量来实现,两种方法能够及时快速准确地检测电离层异常,有效避免发生GBAS完好性风险。

GAST C GBAS traditional ionospheric monitoring method is code carrier divergence monitoring(CCD), which uses a first-order linear time invariant low-pass filter to monitor ionospheric anomalies. It is widely used to detect the change of ionospheric gradient in GBAS. However, due to the fixed time constant of filtering, it is difficult to balance the response time and positioning accuracy of GBAS system. In order to eliminate this limitation, two ionospheric gradient anomaly monitoring methods, GAST D GBAS, are proposed in this paper. The first one optimizes the CCD algorithm to use two low-pass filters for ionospheric anomaly monitoring;The second method is ionospheric gradient monitoring algorithm(IGM), which is realized by monitoring the carrier phase observation of the reference receiver. The two methods can detect ionospheric anomalies in time, quickly and accurately, and effectively avoid the integrity risk of GBAS.