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Global navigation satellite systems
Published in Mike Tooley, David Wyatt, Aircraft Communications and Navigation Systems, 2017
The GNSS receiver can be installed with error detection software known as receiver autonomous integrity monitoring (RAIM). Monitoring is achieved by comparing the range estimates made from five satellites. RAIM is a GNSS receiver function that performs a consistency check on all tracked satellites. This ensures that the available satellite geometry allows the receiver to calculate a position within a specified protection limit:Oceanic 4 nmEn route 2 nmTerminal 1 nmNon-precision approaches 0.3 nm.
Integrity monitoring using multi-GNSS pseudorange observations in the urban environment combining ARAIM and 3D city models
Published in Journal of Spatial Science, 2022
Ahmed El-Mowafy, Bing Xu, Li-Ta Hsu
The concept of RAIM was developed to safeguard the navigation integrity by means of self-contained fault detection at the GNSS navigation receiver. Fault detection, a fundamental task in RAIM, usually relies on statistical hypothesis testing, under the assumption that the observation errors in the fault-free mode are normally distributed with zero mean. One may test the validity of this assumed hypothesis by means of a Chi-square distributed sum-of-squared-residuals (Walter and Enge 1995). Depending on the parametrisation of the underlying model, many implementations of these test-statistics exist (Blanch et al. 2015, Joerger and Pervan 2016, El-Mowafy and Kubo 2017). In addition to application in the observations domain, integrity monitoring can be implemented in the position domain, which is applied in this paper, following the ARAIM Multiple Hypothesis Solution Separation (MHSS) method proposed in (Blanch et al. 2015). The trust in the position solution is evaluated by the Protection Levels (PLs), which are defined as the maximum errors that can possibly occur with probability larger than the allowed Probability of Hazardous Misleading Information (), without an Alert being timely raised (Parkinson and Axelrad 1988). ARAIM requires observing enough number of satellites to enable positioning with some redundancy. Nowadays, this is possible in large sections in the urban environment due to the presence of multiple GNSS constellations.
A Comprehensive Survey on GNSS Interferences and the Application of Neural Networks for Anti-jamming
Published in IETE Journal of Research, 2021
Kambham Jacob Silva Lorraine, Madhu Ramarakula
At the navigation level, Receiver Autonomous Integrity Monitoring (RAIM) based techniques and integration of the inertial navigation system (INS) and GPS are used. However, RAIM is mostly used for spoofing detection and it's too weak against modern spoofers [39]. On the other hand, the impact of jamming signals on inertial navigation is less. Hence, it seems to be effective in tracking the GNSS signals even in a jamming environment. Table 2 summarizes the comparison of different anti-jamming techniques in terms of advantages and limitations and Table 3 gives some of the main existing and recent surveys on anti-jamming.