Receiver Autonomous Integrity Monitoring (RAIM) of GPS and GLONASS

Misra, P.; Bayliss, Edward T.; Lafrey, R R; Pratt, M.; Muchnik, R.

doi:10.1002/j.2161-4296.1993.tb02296.x

Cited by 11 publications

(7 citation statements)

References 7 publications

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“…The efficiency of RAIM is closely dependent on the receiversatellite geometry and this implies that RAIM may not always be available. Many preliminary investigations on RAIM have been performed [128][129][130][131] and the inference is that the stand alone GNSS constellation does not provide the required RAIM availability and GNSS must be augmented if it is to be used as a primary navigation means for en route to non-precision phases of flight. The non GNSS measurements which are helpful to improve the RAIM availability include barometric altitude, receiver clock coasting, geostationary satellite range, etc.…”

Section: Receiver Autonomous Integrity Monitoringmentioning

confidence: 99%

Global navigation satellite systems performance analysis and augmentation strategies in aviation

Sabatini

Moore

Ramasamy

2017

Progress in Aerospace Sciences

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In an era of significant air traffic expansion characterised by a rising congestion of the radiofrequency spectrum and a widespread introduction of Unmanned Aircraft Systems (UAS), Global Navigation Satellite Systems (GNSS) are being exposed to a variety of threats including signal interferences, adverse propagation effects and challenging platform-satellite relative dynamics. Thus, there is a need to characterize GNSS signal degradations and assess the effects of interfering sources on the performance of avionics GNSS receivers and augmentation systems used for an increasing number of mission-essential and safety-critical aviation tasks (e.g., experimental flight testing, flight inspection/certification of ground-based radio navigation aids, wide area navigation and precision approach). GNSS signal deteriorations typically occur due to antenna obscuration caused by natural and man-made obstructions present in the environment (e.g., elevated terrain and tall buildings when flying at low altitude) or by the aircraft itself during manoeuvring (e.g., aircraft wings and empennage masking the on-board GNSS antenna), ionospheric scintillation, Doppler shift, multipath, jamming and spurious satellite transmissions. Anyone of these phenomena can result in partial to total loss of tracking and possible tracking errors, depending on the severity of the effect and the receiver characteristics. After designing GNSS performance threats, the various augmentation strategies adopted in the Communication, Navigation, Surveillance/Air Traffic Management and Avionics (CNS+A) context are addressed in detail. GNSS augmentation can take many forms but all strategies share the same fundamental principle of providing supplementary information whose objective is improving the performance and/or trustworthiness of the system. Hence it is of paramount importance to consider the synergies offered by different augmentation strategies including Space Based Augmentation System (SBAS), Ground Based Augmentation System (GBAS), Aircraft Based Augmentation System (ABAS) and Receiver Autonomous Integrity Monitoring (RAIM). Furthermore, by employing multi-GNSS constellations and multi-sensor data fusion techniques, improvements in availability and continuity can be obtained. SBAS is designed to improve GNSS system integrity and accuracy for aircraft navigation and landing, while an alternative approach to GNSS augmentation is to transmit integrity and differential correction messages from ground-based augmentation systems (GBAS). In addition to existing space and ground based augmentation systems, GNSS augmentation may take the form of additional information being provided by other on-board avionics systems, such as in ABAS. As these on-board systems normally operate via separate principles than GNSS, they are not subject to the same sources of error or interference. Using suitable data link and data processing technologies on the ground, a certified ABAS capability could be a core element of a future GNSS Space-Ground-Aircraft Augmentation Network ...

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Section: Receiver Autonomous Integrity Monitoringmentioning

confidence: 99%

Global navigation satellite systems performance analysis and augmentation strategies in aviation

Sabatini

Moore

Ramasamy

2017

Progress in Aerospace Sciences

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“…Integrity monitors have been widely deployed in aviation navigation systems, most notably in systems based on GPS positioning. A prominent example of integrity monitoring is Receiver Autonomous Integrity Monitoring (RAIM), in which a GPS receiver tests the residuals of the position solution to detect possible anomalous measurements . Other examples of integrity monitoring are found in GPS augmentation systems, notably in Space Based Augmentation Systems (SBAS) and Ground Based Augmentation Systems (GBAS) .…”

Section: Motivating Examplementioning

confidence: 99%

Impact of Time-Correlation of Monitor Statistic on Continuity of Safety-Critical Operations

Rife

Misra

2012

J Inst Navig

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Integrity monitors are an essential component of ensuring the quality of navigation measurements for safety‐critical GNSS augmentation systems. The sensitivity of these monitors is closely related to requirements limiting monitor false alarms. This paper shows that the risk of false alarms interrupting safety critical operations (loss of continuity) is closely tied to monitor‐noise correlation. Analysis shows that specific continuity risk may be as high as 50% for conventional monitor implementations, when time correlation is considered. This paper presents an alternate two‐threshold monitor implementation, which features both a subcritical threshold and a critical threshold, only the latter of which triggers a loss of continuity. Using this two‐threshold implementation, we introduce methods to compute specific continuity risk in the presence of time‐correlated noise. Subsequently, through simulation, we quantify how specific continuity risk is influenced by varying levels of time‐correlation, which may be present in the raw monitor data or introduced by smoothing. Copyright © 2012 Institute of Navigation.

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“…Receiver autonomous integrity monitoring (RAIM) is one of the most popular methods of integrity monitoring (Lee 1992;Misra et al 1993). In a RAIM algorithm, if the threshold value for fault detection is too large, then the RAIM algorithm may not detect faults in measurements and will not provide positioning integrity.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear fault detection threshold optimization method for RAIM algorithm using a heuristic approach

Liu

Tan

et al. 2015

GPS Solut

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The threshold value used in receiver autonomous integrity monitoring algorithms to identify faults has a significant impact on positioning integrity and GPS/ GNSS availability. The value is usually selected empirically or under certain distribution assumptions; its calculation for a non-Gaussian test statistic has not been solved. For fault detection methods using a particle filter, a new heuristic method is proposed to select an appropriate fault detection threshold value using an optimization model. In this method, a non-Gaussian cumulative log likelihood ratio (LLR) value is used as the test statistic. Its threshold is determined using an integrity risk minimization problem with an availability constraint. Since there is no closed form for this optimization model, a genetic algorithm with a local search strategy is adopted to find a near-optimal solution. Experimental results show that this method can be used to compute the non-Gaussian fault detection threshold value subject to different availability constraints. Comparisons with empirical and distribution-based methods indicate that while meeting the same probability for falsealert constraint, the probability of missed detection in the optimized approach is much lower than for other methods, especially for small numbers of errors. Since the cumulative LLR value does not exhibit obvious statistical features for any distribution, the performance of our optimized approach is stable for different test cases and satellite data sets.

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Receiver Autonomous Integrity Monitoring (RAIM) of GPS and GLONASS

Cited by 11 publications

References 7 publications

Global navigation satellite systems performance analysis and augmentation strategies in aviation

Global navigation satellite systems performance analysis and augmentation strategies in aviation

Impact of Time-Correlation of Monitor Statistic on Continuity of Safety-Critical Operations

Nonlinear fault detection threshold optimization method for RAIM algorithm using a heuristic approach

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