Explore the vast range of titles available.

Satellite-based augmentation systems ensure the accuracy and integrity of aircraft position estimates derived from radio signals broadcast by the Global Navigation Satellite System. The United States’ Wide Area Augmentation System (WAAS) protects users of the Global Positioning System from threats generated by ionospheric disturbances. The means by which WAAS mitigates these threats depends upon their magnitude. This paper addresses: a) how WAAS monitors the level of ionospheric perturbation over North America; b) how various availability and integrity concerns have influenced the implementation of WAAS’s extreme and moderate ionospheric storm detectors; c) how the algorithms governing these implementations have evolved since WAAS’s commissioning in 2003; and d) how the largest ionospheric storms of the past two solar cycles can be ranked according to their impact on WAAS. A subsequent companion paper will address the evolution of the WAAS methodology for protecting users from the adverse influence of more moderate ionospheric disturbances.

Intelligence Augmentation Systems (IAS) allow for more efficient and effective corporate processes by means of an explicit collaboration between artificial intelligence and human judgment. However, the higher degree of system autonomy, along with the enrichment of human capabilities, amplifies pre-existing issues of the distribution of moral responsibility: If an IAS has caused harm, firms who have operated the system might argue that they lack control over its actions, whereas firms who have developed the system might argue that they lack control over its actual use. Both parties rejecting responsibility and attributing it to the autonomous nature of the system leads to a variety of technologically induced responsibility gaps. Given the wide-ranging capabilities and applications of IAS, such responsibility gaps warrant a theoretical grounding in an ethical theory, also because the clear distribution of moral responsibility is an essential first step to govern explicit morality in a firm using structures such as accountability mechanisms. As part of this paper, first the necessary conditions for the distribution of responsibility for IAS are detailed. Second, the paper develops an ethical theory of Reason-Responsiveness for Intelligence Augmentation Systems (RRIAS) that allows for the distribution of responsibility at the organizational level between operators and providers. RRIAS provides important guidance for firms to understand who should be held responsible for developing suitable corporate practices for the development and usage of IAS.

To guarantee the integrity of a global navigation satellite system (GNSS) for safety-critical users, a satellite-based augmentation system (SBAS) makes use of the integrity monitoring architecture, of which the signal quality monitor (SQM) is an important component to address the potential risks caused by satellite-induced signal anomalies. Due to the introduction of dual-frequency multi-constellation (DFMC) techniques in 2025, the ranging uncertainty will be reduced by the elimination of first-order ionospheric delay, but the biases measured in each individual signal will be inflated by the ionosphere-free combinations. Moreover, multiple modulations of DFMC signals might introduce applicability uncertainty of a traditional SQM method that has been protecting GPS L1C/A signal only. Thus, higher requirements are put forward for future SQM methods in detection sensitivity and modulation independence. This paper first proposes a design methodology for the SQM algorithm for BDS B1C/B2a signals, which could be easily extended to the DF combinations of other GNSS core constellations. Then, by comparing the performances of SQM baseline algorithms based on traditional multi-correlator and emerging chip domain observables (CDOs), respectively, the superiority of CDO-based SQM is declared. Detailed design iterations are further discussed, including the algorithm practicalization with optimizing code-phase bin length and lowering sampling frequency, as well as the metric simplification, to promote the overall performance while preserving a lower implementation complexity. Ultimately, a CDO-based SQM algorithm for BDS B1C/B2a signals is reached, which would be considered as an effective candidate in new generation DFMC SBASs.

The Wide Area Augmentation System(WAAS) is the most mature satellite-based augmentation system currently available to provide higher performance navigation and positioning services for civil aviation users. WAAS broadcasts a wide range of differential correction data and integrity information to users via Geostationary Orbit(GEO) satellites to achieve enhanced navigation performance of GNSS. This paper selects the enhanced messages broadcast by different GEO satellites from February 1st to February 7th, 2022, decodes and compares the data of the messages MT2-5 and MT25, and analyzes the differences of the messages broadcast by different GEOs.

This paper addresses the potential threats posed by large ionospheric gradients acting between ground-based augmentation system (GBAS) reference stations and aircraft during approach. Current GBAS stations rely on conservative threat models to mitigate ionospheric gradient threats, limiting system availability and continuity.To solve these issues, previous research has introduced a methodology for real-time detection and estimation of ionospheric gradients using a network of dual-frequency, multi-constellation global navigation satellite system monitoring stations. This paper proposes to expand this approach by including the derivation of an uncertainty model for the estimated gradient slope, allowing the threat model to be substituted with the near real-time estimated and overbounded gradient slope in current GBAS algorithms.Evaluations with simulated and real anomalous gradients produced by equatorial plasma bubbles demonstrate the efficacy of this methodology, indicating its potential to enhance GBASs by dynamically detecting, estimating, and overbounding the estimated anomalous gradients instead of relying solely on worst-case models, thus improving system availability and continuity.

Ionospheric storms and scintillation cause great impact on the service performance of single-frequency Satellite-Based Augmentation System (SBAS). On the one hand, conservative estimation method of the ionospheric integrity information can lead to the problem of over-wrapping in the pseudorange domain and cannot make it optimal to the service performance of SBAS. On the other hand, the performance of the ionospheric Kriging method is unstable in some regions with active ionospheric. Meanwhile, there will be a growing number of dual-frequency users with the development of GNSS. This paper proposes IFree Filter-based user positioning algorithm for SBAS and analyzes the positioning performance of 36 Monitor stations in North America. First, high-order differential method is used to detect cycle slip of dual-frequency carrier-phase observation, and chi-square test is used to detect and eliminate outliers. Then, the dual-frequency pseudorange is smoothed with the dual-frequency carrier phase after cycle slip repair, and the ionospheric delay is treated with IFree filter. Compared with the Wide Area Augmentation System (WAAS) algorithm, the signal-in-space correction accuracy by the proposed algorithm is significantly improved, which can provide LPV200 services for most regions in North America and even CAT-I services for some regions, and can be applied as key technologies to monitor stations and information processing center of the civil services platform for BeiDou Satellite-Based Augmentation System (BDSBAS).

Ground-Based Augmentation System (GBAS) is a GNSS augmentation system that meets International Civil Aviation Organization (ICAO) requirements to support precision approach and landing. GBAS is based on local differential GNSS technique with reference stations located around an airport to provide necessary integrity and accuracy. The performance of the GBAS system can be affected by gradient in the ionospheric delay between aircraft and reference stations. A nominal ionospheric gradient, which is bounded by a conservative error bound, is represented by a parameter σvig. The parameter σvig is commonly determined using station pair to GNSS Continuous Operating Reference Station (CORS) data. The station-pair method is susceptible to doubling of the estimation error of receiver inter-frequency bias (IFB) and is not suitable with the CORS conditions in Indonesia. We propose a satellite-pair method that is found to be more suitable for the CORS network over Indonesia which is centered in Java and Sumatra islands. An overall value of σvig (5.21 mm/km) was obtained using this method along with preliminary results of a comparison of σvig from Java and Sumatra islands.

From the beginning of World War II, dual-axis tracking radars have played an important role in the tracking of missiles in test ranges. These radars operate mostly in S- or C-band of frequencies. However, these Radars have associated problems with the costly maintenance budget, various errors that creep into the data, and inter-radar bias correction. The modern-day global navigation satellite system (GNSS) together with space-based augmentation systems (SBAS) have provided scope to obtain internally generated and telemetered trajectory data from the missile under test (MUT) from the onboard GNSS receiver with SBAS capabilities within comparable or better accuracies. This research presents a comparison of the precession parameters of the MUT’s position solutions between data from several tracking radars and those from the enhanced GNSS data. Also, experiments have been conducted using various satellite navigation constellations including NavIC and SBAS augmentation to demonstrate the improvement in accuracy and precession parameters applicable to the Indian scenario. To compete with the outcomes of contemporary satellite-based navigation system together with the augmentation systems for trajectory generation of cooperative missile targets, radar manufacturers must reconsider their design philosophies for usage on missile test ranges.

The BeiDou Satellite-Based Augmentation System (BDSBAS), based on the Radio Technical Commission for Aeronautics (RTCA) protocol, aims to provide high-precision, single-frequency positioning with integrity assurance for civil aviation users in China and surrounding regions. Given the anticipated high solar activity between 2023 and 2025, ionospheric anomalies may degrade positioning accuracy and significantly impact BDSBAS integrity performance. To enhance BDSBAS integrity, this study evaluates and analyzes the system’s ionospheric degradation parameters for 2023. The results indicate that during the active ionospheric period in 2023, the rate of ionospheric grid delay changes exceeding the limits of the currently broadcasted parameters increased by 0.86%, posing potential integrity risks compared to 2022. To address this issue, we propose a novel algorithm for ionospheric degradation parameters and assess its applicability, stability, and effectiveness using BDSBAS single-frequency service message data from IGS monitoring stations in China. Statistical analysis in the localization domain demonstrates that the new method reduces the rate of ionospheric degradation parameters exceeding the threshold by 1.10% in 2023–2024. This approach significantly enhances BDSBAS integrity service capabilities, supporting its performance improvement and official deployment.

Currently, many commercial airline aircraft cannot perform three-dimensionally guided approaches based on satellite-based augmentation systems. We propose a system to rebroadcast the correction and integrity data via a data link as provided by the ground-based augmentation system such that aircraft equipped with a GPS landing system (GLS) can use the wide-area corrections and perform localizer performance with vertical guidance (LPV) approaches while maintaining the same level of integrity. In consequence, the system loses some availability and the time to alert is slightly increased. We build a prototype system and present data collected for one week, confirming technical feasibility. There is a loss of 5.3 percent of availability during a 1-week data collection cycle in which we compared our system to standalone LPV service. We tested our prototype with two commercially available GLS receivers with positive results and successfully demonstrated the functionality with a conventional Airbus 319 equipped with a standard GLS receiver.