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 operational low cost GNSS software receiver for microsatellites

Abstract: This paper presents a new low cost GNSS Software (SW) receiver for Microsatellites. TES Electronic Solutions (Bruz, FRANCE) has been chosen by CNES for developing and manufacturing this equipment which should be tested on board the scientific microsatellites named TARANIS and MICROSCOPE that will be launched in 2013 and 2014. The GNSS receiver under development is a high-performance equipment specially designed and optimized for the needs and constraints of small platforms for which small volume, low mass and low power consumption are important parameters. This equipment is based on COTS (Commercials off The Shelf) in order to exploit the performance of the advanced technology developed for terrestrial applications and to reduce significantly the global cost of the equipment. The structure of this GNSS receiver is organized around a reconfigurable architecture with the use of one FPGA (Field Programmable Gate Array) associated with one DSP (Digital Signal Processor). The GNSS function is then split in two main parts according to the real time requirements of the processing and navigation operations. The hardware (HW) architecture has been optimized to be able to support a low power mode through a fractioned activity that has been implemented by introducing standby time frames during the mission. An orbital extrapolator is also implemented for propagating position and velocity without pseudo range measurements. This receiver is able to process GPS (L1) and GALILEO (E1) signals simultaneously in the first version of the software and will be able to evolve in a second step to a dual frequency mode, compatible with E5a/E1, or with E5b/E1. This GNSS receiver dedicated to low earth orbit (LEO) satellites will withstand the radiation environment therefore the hardware and software architecture has been defined to reduce the single event effects (SEE) and to maximize the service availability.

TEC and Instrumental Bias Estimation of GAGAN Station Using Kalman Filter and SCORE Algorithm

Abstract: The standalone Global Positioning System (GPS) does not meet the higher accuracy requirements needed for approach and landing phase of an aircraft. To meet the Category-I Precision Approach (CAT-I PA) requirements of civil aviation, satellite based augmentation system (SBAS) has been planned by various countries including USA, Europe, Japan and India. The Indian SBAS is named as GPS Aided Geo Augmented Navigation (GAGAN). The GAGAN network consists of several dual frequency GPS receivers located at various airports around the Indian subcontinent. The ionospheric delay, which is a function of the total electron content (TEC), is one of the main sources of error affecting GPS/SBAS accuracy. A dual frequency GPS receiver can be used to estimate the TEC. However, line-of-sight TEC derived from dual frequency GPS data is corrupted by the instrumental biases of the GPS receiver and satellites. The estimation of receiver instrumental bias is particularly important for obtaining accurate estimates of ionospheric delay. In this paper, two prominent techniques based on Kalman filter and Self-Calibration Of pseudo Range Error (SCORE) algorithm are used for estimation of instrumental biases. The estimated instrumental bias and TEC results for the GPS Aided Geo Augmented Navigation (GAGAN) station at Hyderabad (78.47°E, 17.45°N), India are presented.

An analysis of positioning and map-matching issues for GNSS-based road user charging

Abstract: The time for new paradigms for pay-per-use road use charging (RUC) has come, and it is still unclear whether or not current Global Navigation Satellite Systems (GNSS) supply reliability enough to lead the technological deployment. It is the general belief for RUC stakeholders that GNSS is the most flexible and cost-efficient technology for such a large deployment. However, the German experience of Toll Collect shows that GNSS must be strongly complemented by road side equipments to reach the necessary charging reliability standards. This paper analyzes some significant points of a GNSS-based RUC schemes, with a special emphasis on relevant map-matching issues. This analysis is complemented by our proposals for supporting GNSS with aiding onboard sensors and maps, and discussions about how the charging reliability may result affected by that. The paper finishes with a summary of the most remarkable conclusions achieved in our investigations.

Determining the optimal site location of GNSS base stations

Abstract: The relative positioning technique plays an essential role in Global Navigation Satellite System (GNSS) surveys. Simultaneous observation at base and rover stations eliminates the majority of error sources thus the quality of a positioning solution can be substantially improved. However, topographic obstruction is still a key issue affecting positioning quality. In this study, an integrated approach for analyzing the impact of topographic obstruction on GNSS relative positioning has been developed. By considering varied satellite geometry according to actual terrain variation, this approach can be used to realistically determine satellite visibility condition for a specific base station with respect to any rover station. Furthermore, a base station quality index (BSQI) is proposed as an explicit indication of the sufficiency in a relative positioning. By incorporating the proposed approach, one can immediately identify an optimal site location for a GNSS base station with subsequent GNSS field survey thus achieved in a more reliable and cost-efficient manner.

The Availability of Space Service for Inter-Satellite Links in Navigation Constellations

Abstract: Global navigation satellite systems (GNSS) are widely used in low Earth orbit (LEO) satellite navigation; however, their availability is poor for users in medium Earth orbits (MEO), and high Earth orbits (HEO). With the increasing demand for navigation from MEO and HEO users, the inadequate coverage of GNSS has emerged. Inter-satellite links (ISLs) are used for ranging and communication between navigation satellites and can also serve space users that are outside the navigation constellation. This paper aims to summarize their application method and analyze their service performance. The mathematical model of visibility is proposed and then the availability of time division ISLs is analyzed based on global grid points. The BeiDou navigation constellation is used as an example for numerical simulation. Simulation results show that the availability can be enhanced by scheduling more satellites and larger beams, while the presence of more users lowers the availability. The availability of navigation signals will be strengthened when combined with the signals from the ISLs. ISLs can improve the space service volume (SSV) of navigation constellations, and are therefore a promising method for navigation in MEO/HEO spacecraft.