Ionospheric Anomaly Detection to Support the BDSBAS

Abstract

Corrections and integrity bounds of the ionospheric delay generated at the Satellite-Based Augmentation System (SBAS) for aviation users may confront a wide range of ionospheric conditions over its update interval. Ionospheric irregularities affecting Single Frequency (SF) SBAS can cause the risk of service integrity and a loss of service continuity. The aim of the Ionospheric Anomaly Detection (IAD) scheme is to detect the effect of ionospheric irregularities on the SBAS SF service operational capability over China. It will help in establishing statistical anomaly models and then provides a high level of service for aviation users. The IAD scheme uses a fusion protocol to reach consensus among subdetectors, which monitor different ionospheric features. Moreover, the threshold of every sub-detector is derived based on system availability. We analyze the IAD scheme by practical ionosphere observations recorded at the crustal movement observation network of China in 2015. It successfully identifies ionospheric anomalies affecting SF SBAS and conforming with physical characteristics. Furthermore, it provides sufficient detection reliability. The statistical results illustrate that the difference of 95% residual error for post-ionosphere correction between normal and anomalous zones is between 1.4 m and 3.2 m. The average value is 2.1723 m. Additionally, there exist two types of ionospheric anomalies affecting SBAS SF service over China. The range is mainly at latitude 15 •-35 • N. The occurrence time is mainly at GPS time 4-15 h and 12-19 h, respectively.

Principle and performance of BDSBAS and PPP-B2b of BDS-3

“…The corresponding single frequency and dual frequency positioning performances were described and analyzed (Chen et al, 2020;Yang et al, 2021); the dual frequency integrity parameter performance of BDSBAS (Shao et al, 2020) and the ephemeris correction performance of BDSBAS in China (Jin et al, 2021) were also analyzed. Since the ionospheric correction is an important influencing factor, some scholars analyzed the ionospheric anomaly detection method of BDSBAS (Bao et al, 2019).…”

“…The ionospheric model of BDSBAS adopts the ionospheric parameters determined by the ground monitoring stations, and the 5° × 5° Grid Ionospheric Vertical Delay (GIVD) is obtained using the Inverse Distance Weighting (IDW) method. The user needs to calculate the ionospheric correction of the location by interpolating the values at its surrounding grid points (Bao et al, 2019;Ma et al, 2021). However, there are only about 80% grid points in China whose ionospheric delay parameters can be reliably calculated, which greatly reduce the availability and continuity of the ionospheric corrections in China's border areas due to the lack of ionospheric monitoring information in China's surrounding areas.…”

Design of Ionospheric TEC Gradient Anomaly Detection Platform Based on GNSS

“…Common ionospheric anomaly detection techniques include chi-square test and logarithmic likelihood ratio test [2]. Walter T et al used chi-square test for anomaly detection, but the calculation of ionospheric vertical error of fusion qualified dot in satellite-based enhancement system was susceptible to influence [3].…”

“…Liu Tong et al, based on the maximum and minimum eigenvalue algorithm, used different satellites to construct a metric matrix of ionospheric delay at different times to detect the ionosphere in time, but the calculation process is cumbersome [5]. Compared with TEC gradient test, the rate of TEC change index (ROTI) is more sensitive to ionospheric anomalies [2]. Zhe et al proved that ROTI was consistent with ionospheric scintillation activity and ionospheric time variation under different geomagnetic storm conditions [6].…”

Distribution of Reference Stations: Initial Explore on the Optimal Selection Strategy

“…The Federal aviation administration (FAA) has developed the Satellite‐based augmentation system (SBAS), as augmentations to the Global navigation satellite system (GNSS) to permit safe navigation and guidance for aircraft [ 1 ] . The BeiDou satellite‐based augmentation system (BDSBAS), for example, is scheduled to be deployed and will provide two service modes to service China and its surrounding areas, named as Single frequency (SF) mode and Dual‐frequency multi‐constellation (DFMC) mode [ 2 , 3 ] . The BeiDou navigation satellite system (BDS) and Global positioning system (GPS) will be augmented initially [ 4 ] .…”