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.

A Novel VLSI Architecture for Multi-Constellation and Multi-Frequency GNSS Acquisition Engine

Abstract: This paper proposes a novel VLSI architecture of GNSS acquisition engine based on short-time correlation combined with an FFT scheme. The architecture supports multi-constellation systems and multi-frequency satellite signals flexibly by the manner of time-division multiplexing. The supported signals include GPS, BDS, GLONASS, GALILEO, QZSS, IRNSS, and SBAS. Compared with other direct acquisition structures, the search efficiency of the acquisition engine is improved by using the IF playback structure. Based on the characteristics of L1C and B1C signal spread spectrum codes, an efficient generation method and the circuit structure of Legendre sequence which is compatible with L1C and B1C spread spectrum codes are proposed. It can effectively reduce the die area of the spread spectrum code generator and the generation time of the L1C/B1C spread spectrum code. Combining with the acquisition scheme adopted in this paper, the structure of the short-time correlators’ array is optimized, and the maximum clock frequency of the acquisition engine is significantly improved. The acquisition engine proposed in this paper is implemented in a 55-nm CMOS technology. The system occupied a silicon area of 2.1 mm2 and consumes only 72.02-mW power while realizing the maximum clock frequency at about 333.33 MHz.

Modeling and monitoring of new GNSS signal distortions in the context of civil aviation

Abstract: GNSS is used nowadays in various fields for navigation and positioning including safety -of-life applications. Among these applications is civil aviation that requires a very high quality of service for the most demanding phases of flight in terms of integrity, accuracy, availability and continuity. To meet these requirements any source of potential service degradations has to be accounted for. One such example is GNSS signal distortions due to the satellite payload which can manifest in two ways: nominal distortions that are generated by healthy satellites due to payload imperfections and nonnominal distortions that are triggered by a satellite payload failure. The thesis first looks at the nominal distortions through GPS L1 C/A and Galileo E1C signals. Different types of observations are used based on correlation or chip domain visualization, and using high-gain and omnidirectional antennas. After the observation of nominal distortions, the dissertation investigates the non-nominal distortions due to the payload failure. Supported by the groundwork performed by civil aviation on signal distortion for the GPS L1 C/A signal, this dissertation aims at proposing new distortions models associated to the new GPS and Galileo signals that will be used by civil aviation after 2020. In particular, new TMs for new signals (GPS L5, Galileo E5a and Galileo E1C) are proposed. Finally, in this dissertation is built an appropriate monitor, referred to as SQM that is able to detect any distortion from the proposed TMs (for new signals) that could lead to a position integrity failure. Regarding GPS L1 C/A signal monitoring, such SQM is today implemented in GNSS augmentation systems including GBAS and SBAS. The current monitors are based on the analysis of the correlation function.

Breaking the Ice: Navigating in the Arctic

Abstract: Arctic navigation is becoming increasingly important, because oil exploration and normal shipping in the region are both on the rise. Navigation integrity is particularly important, because an accident could be very damaging to the sensitive Arctic environment. Thus, this article investigates the Arctic extension of space-based augmentation systems (SBAS) such as WAAS, EGNOS, and MSAS. More specifically, it analyzes the potential benefit of adding new SBAS reference stations for the far North, use of Iridium satellites to broadcast integrity information to the users, and multi-constellation GNSS to improve vertical performance.

The SGR-ReSI - A new generation of space GNSS receiver for remote sensing

Abstract: SSTL has undertaken pioneering work in spaceborne GPS and GNSS, ranging from miniaturised space GPS receivers, to the GIOVE-A Galileo demonstrator satellite, which itself carried an experimental GEO GPS receiver. Recent activities in GNSS remote sensing undertaken by SSTL have included new reflected GNSS measurements over the poles from the experiment on the UK-DMC satellite, and in-orbit ionospheric scintillation measurements in connection with the Shrewsbury School instigated POISE experiment. SSTL with partners from The National Oceanographic Centre, the University of Bath and the Surrey Space Centre have been developing a new generation GNSS instrument, with funding from the UK Centre for Earth Observation Instrumentation (CEOI), to further exploit GNSS potential for remote sensing in the fields of ocean and atmospheric monitoring. GNSS-Radio Occultation is a technique that is already well established and current satellite missions are providing valuable data to scientists around the world. GNSS Reflectometry, on the other hand, is a relatively new application and this technique seeks to derive information about the Earth by looking at GNSS signals that have been reflected off the Earth's surface and subsequently received by a satellite in low Earth orbit. In the process of reflecting, these signals are distorted by the reflecting surface and, through the use of inversion models, it is possible to subsequently derive information about that surface from the signals. The driving application for this development is the monitoring of the Earth's oceans and, in particular, information about ocean roughness and wind speeds could be derived. Reflections off land and ice have also been detected and potentially contain a wealth of useful information. While the concept has been proved, more data from orbit is required to improve the models that will allow this technique to become a useful tool to scientists. This need for more data is what the development of the SGR-ReSI (Space GNSS Receiver - Remote Sensing Instrument) seeks to address. At its heart, the SGR-ReSI is a highly versatile, multi-frequency GNSS navigation receiver. With the addition of multiple front-ends, reconfigurable DSP capabilities, a small data recorder and specialised antennas, the SGR-ReSI will support both Reflectometry and Radio Occultation applications. Building on SSTL's small satellite expertise and using state of the art technology, the instrument aims to provide a highly capable yet relatively compact and affordable way of studying the Earth from orbit, with core technology that can be reused for a new family of navigation-grade receivers.

Accurate Relative Localization for Land Vehicles with SBAS Corrected GPS/INS Integration and V2V Communication

Abstract: In this paper, different algorithms for performing relative localization based on GNSS measurements only are presented. The focus of this work is to provide an accurate and reliable distance vector between moving vehicles on the road. Therefore, two different algorithms are described and evaluated with real data gathered from several scenarios and test sites. To achieve communication between the vehicles the 802.11p standard for wireless automotive communication is utilized. Moreover, an extension to transmit GNSS raw data in real-time is introduced. Even though the main focus is on relative localization, an absolute position estimate for the ego vehicle is often required as well. In order to provide a stabilized absolute position, orientation and velocity of the vehicle, a Bayes filter implementation to integrate GPS and in-vehicle INS measurements is proposed. Additionally, a vehicular motion model, which describes the dynamics, is applied. The algorithms are tested and evaluated with several prototyping test vehicles which are equipped with reliable ground truth sensors to generate reference trajectories. The paper concludes with the generated results and gives an outlook to potential applications for relative localization in automotive domain.