GNSS augmentation

About: GNSS augmentation is a research topic. Over the lifetime, 2478 publications have been published within this topic receiving 28513 citations. The topic is also known as: SBAS & Satellite Based Augmentation System.

Satellite Based Augmentation Systems

Abstract: Satellite-based augmentation systems (SBAS s) are designed to enhance the performance of standard global navigation satellite system (GNSS ) positioning. SBASs improve the positioning accuracy by providing corrections for the largest error sources. More importantly, SBASs provide assured confidence bounds on these corrections that allows users to place integrity limits on their position errors. Several systems have been implemented around the world and several more are in development. They have been put into place by civil aviation authorities for the express purpose of enhancing air navigation services. However, SBAS services have been widely adopted by other user communities, as the signals are free of charge and easily integrated into GNSS receivers.

EUROFIX: definition and current status

Abstract: The existing Loran-C infrastructure may with some minor changes become a very powerful augmentation system for GNSS. By additional modulation of the Loran-C pulses a long-range data channel can be established which enables broadcasting of DGNSS correction data and integrity information to GNSS users. Unlike other DGNSS services Eurofix offers a full navigation back-lip system in case GNSS fails. The applied additional three-level modulation is fully balanced so it has negligible influence on the basic Loran-C positioning accuracy. Since 1989 Delft University has been working on this system called Eurofix. The user may expect DGNSS accuracies of better than 5 meters (95%) over the full coverage area that eventually will cover entire Europe. During normal operational conditions the Loran-C ASF model imperfections stored in the receiver are continuously calibrated by the found precise DGNSS positions thereby introducing an efficient zero-baseline DLoran-C system. So, during periods of poor GNSS reception, highly calibrated Loran-C may take over. This way, Eurofix offers the user highly accurate DGNSS data, as well as external GNSS integrity and improved radionavigation availability. The German DOT in close cooperation with NELS started experimental Eurofix transmissions in February 1997. The continuing successful DGPS performance tested in France, Germany, the Netherlands and Switzerland mane NELS decide to extent Eurofix in 1998 to another three Loran-C stations at Lessay (France), Voerlandet (South Norway) and Bo (north Norway). This will make Eurofix available in all NELS countries ranging from the North Cape down to the Pyreneans. These four stations also allow extensive testing of the Regional Area Augmentation System capability of Eurofix. As RAAS may significantly reduce temporal and spatial correction data decorrelation further improvements of the system are anticipated.

Latency Determination and Compensation in Real-Time Gnss/ins Integrated Navigation Systems

Abstract: Unmanned Aerial Vehicle (UAV) technology is now commonplace in many defence and civilian environments. However, the high cost of owning and operating a sophisticated UAV has slowed their adoption in many commercial markets. Universities and research groups are actively experimenting with UAVs to further develop the technology, particularly for automated flying operations. The two main UAV platforms used are fixed-wing and helicopter. Helicopter-based UAVs offer many attractive features over fixed-wing UAVs, including vertical take-off, the ability to loiter, and highly dynamic flight. However the control and navigation of helicopters are significantly more demanding than those of fixed-wing UAVs and as such require a high bandwidth real-time Position, Velocity, Attitude (PVA) navigation system. In practical Real-Time Navigation Systems (RTNS) there are delays in the processing of the GNSS data prior to the fusion of the GNSS data with the INS measurements. This latency must be compensated for otherwise it degrades the solution of the navigation filter. This paper investigates the effect of latency in the arrival time of the GNSS data in a RTNS. Several test drives and flights were conducted with a low-cost RTNS, and compared with a high quality GNSS/INS solution. A technique for the real-time, automated and accurate estimation of the GNSS latency in low-cost systems was developed and tested. The latency estimates were then verified through cross-correlation with the time-stamped measurements from the reference system. A delayed measurement Extended Kalman Filter was then used to allow for the real-time fusing of the delayed measurements, and then a final system developed for on-the-fly measurement and compensation of GNSS latency in a RTNS.

Assessing absolute and relative accuracy of recreation-grade and mobile phone GNSS devices: a method for informing device choice

Abstract: The affordability/availability and portability of recreation-grade receivers and mobile devices, compared with commercial survey Global Navigation Satellite Systems (GNSS), commonly referred to as Global Positioning System, make them worthy of consideration for student fieldwork and research. While empirical evidence of the relative accuracy of low-cost GNSS receivers in open areas is currently limited, initial findings suggest that levels of relative accuracy, as opposed to absolute accuracy, make these devices an inexpensive and manageable technology for measuring the relative location of land features. Given the current speed at which GNSS technology advances, it is important to have an appreciation of any proposed device's accuracy. This paper presents a method for evaluating the levels of absolute and relative accuracy of various devices, which can inform the choice of device for particular survey-based projects. It can also be used to indicate a ‘best practice’ approach to using GNSS devices in a research and study context, through an assessment of the factors influencing levels of relative accuracy, such as the length of time a device is left to settle before recording a point. In addition, this method can be a useful exercise in and of itself for helping students better understand absolute and relative accuracy, the capabilities of their own mobile hardware, and the potential use of recreation-grade and mobile devices in a range of scenarios both within and beyond the academy.

GNSS receiver tracking performance analysis under distance-decreasing attacks

Abstract: Numerous works have investigated the vulnerability of Global Navigation Satellite Systems (GNSS) against attacks. Upcoming systems make provisions for cryptographic civilian signal protection. However, this alone does not fully protect GNSS-based localization. In this paper, we show that attacks at the physical layer, without modification of navigation messages, can be severely effective. We analyze the influence of the, so called distance decreasing attacks, and we investigate their feasibility and we find that they can be practical and effective. Finally, we consider signal quality monitoring, but it can not readily serve as a countermeasure.