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.

System and method of communicating GNSS information between mobile machines

Abstract: In one embodiment, a method comprising, receiving at a moving vehicle first global navigation satellite systems (GNSS) information broadcasted from a base station and second GNSS information provided by one or more satellites; determining by a processor residing in the vehicle a position of the vehicle based on the first and second GNSS information; and re-broadcasting the first GNSS information to a receiver located remotely from the moving vehicle.

Simulation of GNSS reflected signals and estimation of position accuracy in GNSS-challenged environment

Abstract: The paper describes the development and testing of a simulation tool, called QualiSIM. The tool estimates GNSS-based position accuracy based on a simulation of the environment surrounding the GNSS antenna, with a special focus on city-scape environments with large amounts of signal reflections from non-line-of-sight satellites. The signal reflections are implemented using the extended geometric path length of the signal path caused by reflections from the surrounding buildings. Based on real GPS satellite positions, simulated Galileo satellite positions, models of atmospheric effect on the satellite signals, designs of representative environments e.g. urban and rural scenarios, and a method to simulate reflection of satellite signals within the environment we are able to estimate the position accuracy given several prerequisites as described in the paper. The result is a modelling of the signal path from satellite to receiver, the satellite availability, the extended pseudoranges caused by signal reflection, and an estimate of the position accuracy based on a least squares adjustment of the extended pseudoranges. The paper describes the models and algorithms used and a verification test where the results of QualiSIM are compared with results from collection of real GPS data in an environment with much signal reflection.

An iterative method for attitude determination based on misaligned GNSS baselines

Abstract: Multiple Global Navigation Satellite System (GNSS) antennae systems have been among the well-known approaches to attitude determination of moving platforms in recent years. However, the constraints on the onboard GNSS antennae configuration, that is, installing the antennae baselines along the main axes of the platform, can lead to practical difficulties and inevitable uncertainty. In this contribution we present an iterative method to obtain the accurate attitudes by means of the onboard misaligned baselines. In order to remove the effects of the horizontal and vertical misalignments from GNSS observations of the baselines, attitude-induced corrections have been developed through the relative lever-arm coordinates of the onboard antennae. This approach provides us with more freedom from spatial distribution of the onboard antennae. The performance of the proposed method has been analyzed by simulated data and an actual experiment in low- and high-dynamic situations. The simulation has been designed to evaluate the capability and reliability of the iterative method under the presence of small and large misalignments. The field experiment was carried out in the offshore waters of Kish harbor using three dual-frequency GNSS receivers with choke-ring antennae onboard a survey vessel, which was also equipped with an inertial measurement unit (IMU). The maximum allowable misalignments, the convergence of the iteration, and the advantage of the proposed method over the trigonometric approach in spite of applying the traditional calibration are presented. The long-term stability of GNSS attitude determination as well as IMU accuracy degradation, due largely to the increase in the time-varying biases/noises, have demonstrated the potential of the method to estimate the accuracies and biases of the onboard inertial sensor. The overall results affirm that the presented method can effectively provide the platform attitudes using the misaligned GNSS baselines with as much flexibility as possible for the onboard antennae configuration.

Research on Positioning of High Earth Orbital Satellite Using GNSS

Abstract: The GNSS as a navigation and positioning method has global,all-weather,real time and high precision characteristics.Using it on the high earth orbital satellites in positioning can provide precise orbit and attitude determination,overcome the disadvantage of complex equipment and high cost which using ground measurement and control system to positioning,make it possible to autonomous navigation.New and exciting opportunities become possible if satellites are able to autonomously determine their own orbit.For example,precise onboard orbit determination opens the door to satellites flying in formation.However,receivers in low Earth orbit have virtually the same view of the navigation satellite constellation as receivers on the ground.But satellites orbiting at geostationary altitudes and higher have a severely limited view of the main beams of the GNSS satellites.The main beams are either directed away from these high-altitude satellites or they blocked to a large extent by the Earth.So,using much weaker signals is a fundamental requirement for a high orbital altitude GNSS receiver,but it is certainly not the only challenge.Other unique characteristic of this application must also be considered.On the one hand,dynamic characteristics will be more different at high Earth orbit.High dynamic situation makes it difficult to use weaker signals.On the other hand,Position Dilution of Precision(PDOP)figures are much more higher at geostationary and higher altitudes because visible navigation satellites are concentrated in a much smaller region with respect to the spacecraft antenna.Spacecraft navigation receiver must be designed to withstand a variety of extreme environmental conditions.In this paper,positioning of high earth orbital satellites using GNSS is researched.The visibility of navigation satellites,dynamic characteristics,Geometric dilution of precision are analyzed using single GNSS and integrated GNSS.Through simulation and analyzing,it is verified that using GNSS can realize the positioning of HEO satellite and obtain enough positioning precision requirement.

Extending access to localizer performance with vertical guidance approaches by means of an SBAS to GBAS converter

Abstract: 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.