Ionospheric monitoring in a dual frequency GBAS

Felux, Michael; Gerbeth, Daniel; Circiu, Mihaela-Simona; Caamano, Maria; Stanisak, Mirko

doi:10.1109/aero.2016.7500884

Cited by 5 publications

(7 citation statements)

References 4 publications

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“…Based on the available single frequency corrections (L1/E1 and L5/E5a) Ifree corrections can be formed on the airborne side. In order to remove the ionospheric delay the single frequency corrections have to be generated using the same smoothing time constant [10].…”

Section: 2mentioning

confidence: 99%

Nominal Performance of Future Dual Frequency Dual Constellation GBAS

Gerbeth

Circiu

Caamano

et al. 2016

International Journal of Aerospace Engineering

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In this work an overview of numerous possible processing modes in future dual frequency, dual constellation GBAS is given and compared to the current GAST D standard. We discuss the individual error contributions to GBAS protection levels and give an overview of the general processing. Based on this the consequences when adding a second constellation as well as frequency are investigated. Geometrical implications and changes to the residual differential error bounds are studied separately first. In terms of geometry a comparison between the single and dual constellation case is presented using dilution of precision as metric. The influence on the different sigma contributions when using new satellites (Galileo) and signals (E1, L5, and E5a) is individually discussed based on recent measurements. Final simulations for different varying parameters are carried out to compare relevant processing modes in terms of achieved nominal protection levels. A concluding discussion compares the outcomes and analyzes the implications of choosing one or the other mode.

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Section: 2mentioning

confidence: 99%

Nominal Performance of Future Dual Frequency Dual Constellation GBAS

Gerbeth

Circiu

Caamano

et al. 2016

International Journal of Aerospace Engineering

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“…In this way, ionospheric delays affecting both the ground and the aircraft are estimated by the airborne subsystem using a quantity called pseudo ionospheric delay. The details about this monitoring strategy are found in Felux et al (2016;. Note that each aircraft is required to make its own ionospheric integrity determination because, while it obtains pseudorange corrections from the ground, it has no means to provide its measurements or delay estimates back to the ground station (i.e., the GBAS VDB only communicates information in one direction, from ground to aircraft).…”

Section: Dual-frequency Multi-constellation Gbasmentioning

confidence: 99%

Ground-Based Augmentation Systems Operation in Low Latitudes - Part 1: Challenges, Mitigations, and Future Prospects

Marini-Pereira

Pullen

Moraes

et al. 2021

J. Aerosp. Technol. Manag.

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Ground-based augmentation systems (GBASs) were designed to support civil aviation precision approach and landing with safety and integrity. It has several advantages over traditional navigation aids, allowing airspace usage optimization and reduction of fuel consumption. However, in low-latitude regions such as Brazil, this technology is still not operational due to the strong influence of ionospheric variability. Considering the increased interest in deploying a GBAS station in Brazil along with efforts toward this goal over the last decade, this paper is the first of a two-part series that provides an overview of the key aspects of this technology and the challenges posed when using it in low-latitude regions. The context in which GBAS operates today in midlatitudes is presented along with its fundamental principles and methods of guaranteeing sufficient accuracy, continuity, and integrity for precision operations, particularly those dealing with threatening ionospheric conditions. Finally, the evolution of GBAS to include multiple Global Navigation Satellite System (GNSS) satellite constellations and signal frequencies are discussed with respect to their ability to mitigate ionospheric effects. The conclusion is that the use of these new elements of GBAS seem to be the most viable solution for operating GBAS in low latitudes with high availability.

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“…The largest portion of this will be the receiver clock but it also includes the part of the ionospheric delay that is common to all satellites. For that reason, only the information about the difference in the ionospheric delay between the satellites is contained in the corrections [5].…”

Section: Dual Frequency Monitoringmentioning

confidence: 99%

“…In order to decide now if the difference of the observations from the ground and airborne system poses a threat to the airborne user or not a threshold for this monitor is necessary. In [5] we derived the monitoring threshold based on the airworthiness requirements as given in the CS-AWO [8] and the AC-120 28B [9]. The derivation uses the requirement to land within the touchdown box on the runway.…”

Section: Dual Frequency Monitoringmentioning

confidence: 99%

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Experimental Validation of an Ionospheric Monitoring Scheme for Dual Frequency GBAS

Felux¹,

Circiu²,

Gerbeth³

et al. 2016

Proceedings of the 29th International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS+ 201

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In this paper we describe a method to monitor for a difference in the ionospheric delay observed by a ground station of a Ground Based Augmentation System (GBAS) and an airborne user. In case of detection the affected satellite can be excluded or a switch to an ionospheric free processing mode can be triggered. As it is not possible to estimate the absolute ionospheric delay at the ground station from the transmitted corrections directly, we compare a pseudo-ionospheric delay estimate from the corrections with an ionospheric estimate after removing biases. We then show the performance of the proposed monitoring architecture in flight trials from our GBAS test environment for different scenarios. In order to obtain results for a full constellation we considered an L1/L2 dual frequency combination where the expected noise and multipath is larger than in the L1/L5 case which will be used in an operational GBAS. Results show that even with the larger test statistic and in the single constellation case the monitor is feasible and provides good results. Furthermore, we also show results using the available L5/E5a signals collected during flight tests. Also in this case the performance is good and the threshold was not exceeded despite the low threshold of the monitor due to the marginal geometry. In order to test the reaction of the monitor to ionospheric gradients we injected a simulated error into the airborne measurements. As the monitoring threshold depends on the satellite geometry we show some exemplary results of the impact of different gradient slopes on the test statistic of the affected satellites.

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Ionospheric monitoring in a dual frequency GBAS

Cited by 5 publications

References 4 publications

Nominal Performance of Future Dual Frequency Dual Constellation GBAS

Nominal Performance of Future Dual Frequency Dual Constellation GBAS

Ground-Based Augmentation Systems Operation in Low Latitudes - Part 1: Challenges, Mitigations, and Future Prospects

Experimental Validation of an Ionospheric Monitoring Scheme for Dual Frequency GBAS

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