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 New Solution of Autonomous Navigation for GEO Satellites Based on GNSS

Abstract: To solve problems such as weak navigation signals,lack of visible navigation satellites and poor performance of GDOP for HEO autonomous navigation based on GNSS,this paper presents a new solution,where a new antenna is added to a navigation satellite.Transmit and receive antenna pattern is designed and the required transmit power is studied.Finally,the visibility of navigation satellites,geometric dilution of precision and the precision of the new solution are analyzed.It is verified that a single extra antenna significantly improves visibility,geometric dilution of precision and precision.

Assessment of software-defined gnss receivers

Abstract: The aim of this paper is to trigger a conversation about the assessment, definition of metrics and testing procedures of software-defined GNSS receivers. While the evaluation of traditional (i.e., built on application–specific integrated circuit technology) GNSS receivers is now well–understood, and enjoys both a solid testing industry providing the required equipment and universally agreed figures of merit, the particularities of software–defined radio technologies claim for a more comprehensive approach. In order to account for such a multi–faceted nature, the authors identify sixteen design forces, or dimensions in which a software-defined GNSS can improve. Upon those definitions, a wide list of performance indicators, metrics and procedures are then proposed for each of the identified thrusts. The list can be used as a generative source of ideas when defining key performance indicators in projects, products or services involving a software–defined GNSS receiver.

GNSS-Based Navigation for Lunar Missions

Abstract: Numerous applications, not only Earth-based, but also space-based, have strengthened the interest of the international scientific community in using Global Navigation Satellite Systems (GNSSs) as navigation systems for space missions that require good accuracy and low operating costs. Indeed, already used in Low Earth Orbits (LEOs), GNSS based-navigation GNSS-based navigation systems can maximize the autonomy of a spacecraft while reducing the costs of ground operations, allowing for budget-limited missions of micro- and nanosatellites. This is why GNSS is also very attractive for applications in higher Earth orbits up to the Moon, such as in Moon Transfer Orbits (MTOs). However, while GNSS receivers have already been exploited with success for LEOs, their use in higher Earth orbits above the GNSS constellation is extremely challenging, particularly on the way from the Earth to the Moon, characterized by weaker signals with wider gain variability, larger dynamic ranges resulting in higher Doppler and Doppler rates, critically lower satellite signal availability, and poorer satellite-to-user geometry. In this context, the first research objective and achievement of this PhD research is a feasibility study of GNSS as an autonomous navigation system to reach the Moon, and the determination of the requirements for the design of a code-based GNSS receiver for such a mission. The most efficient combinations of signals transmitted by the GPS, Galileo, and combined GPS-Galileo constellations have been identified by analyzing the theoretical achievable signal acquisition and tracking sensitivities, the resultant constellation availability, the pseudorange error factors, and the geometry error factor and accordingly the achievable navigation performance The results show that GNSS signals can be tracked up to Moon altitude, but not with the current GNSS receiver technology for terrestrial use. The second research objective and achievement is the design and implementation of a GNSS receiver proof-of-concept capable of providing GNSS observations onboard a space vehicle orbiting up to Moon altitude. This research work describes the hardware architecture, the high-sensitivity acquisition and tracking modules and the standalone single-epoch navigation performance of the developed GPS L1 C/A hard-ware receiver, named the WeakHEO receiver. Although they can still be collected, GNSS observations at Moon altitude, if not filtered, but simply used to compute a single-epoch least-squares solution, lead to a very coarse navigation accuracy, on the order of 1 to 10 km, depending on the number and type of signals successfully processed. Therefore, the third and main research objective and achievement is the design and implementation of a GNSS-based orbital filter (OF) determination unit, based on an extended Kalman filter (EKF) and an orbital forces model, able to significantly improve the achievable navigation performance and also to aid acquisition and tracking modules of the GNSS receiver. Simulation results of the OF performance when processing simulated GPS and Galileo observations, but also real GPS L1 C/A observations provided by the WeakHEO receiver (when connected in a hardware in the loop configuration to a full constellation GNSS radio frequency signal simulator), show a positioning accuracy at Moon altitude of a few hundred meters.

Integrity of GNSS-based Train Positioning: From GNSS to sensor integration

Abstract: Accurate and safe train position determination is of great importance for railway systems. Additionally, it has become one of the biggest challenges for the Safety-of-Life (SoL) services in railway transport systems using GNSS techniques. The critical performance requirements of these services promote the users to develop safe Train Positioning Systems (TPSs), in which integrity has to be highly concerned to real-timely monitor the quality of the TPS results. This paper presents a solution to the problem of integrity monitoring in GNSS-based train positioning with a global prospect. Different from the RAIM (Receiver Autonomous Integrity Monitoring) approach, a novel hierarchical architecture is proposed to expand the RAIM concept to the TPSAIM (Train Positioning System Autonomous Integrity Monitoring) domain, where integrity monitoring is closely correlated with both GNSS navigation computation at the local level and sensor integration at the global level. Integrity monitoring and fault detection with respect to the integration of GNSS and the Dead Reckoning (DR), which can be simply implemented with odometer and gyroscope, are investigated with different coupling structures. Results from simulations based on the field experiment illustrate characters of the proposed TPSAIM solution, and demonstrate its capabilities in terms of the effectiveness, coverage and flexibility with various TPS structures and operation conditions.

Global navigation satellite systems (gnss) positioning using precise satellite data

Abstract: Method to estimate parameters derived at least from GNSS signals useful to determine a position, including obtaining at least one GNSS signal observed at a GNSS receiver from each of a plurality of GNSS satellites; receiving global correction information useful to correct at least the obtained GNSS signals from a first set of GNSS satellites, wherein the global correction information includes correction information which is independent from the position to be determined; receiving local correction information useful to correct at least the obtained GNSS signals from a second set of GNSS satellites, wherein the local correction information includes correction information which is dependent on the position to be determined; processing the obtained GNSS signals from the first set of GNSS satellites by using the global correction information; and processing the obtained GNSS signals from the second set of GNSS satellites by using the local correction information.