As signals emitted by global navigation satellite systems (GNSS) propagate toward users on or near the surface of the Earth, they experience delay due to the presence of charged particles in the ionosphere. Currently, ionospheric delay is the largest source of GNSS positioning error. To guarantee the safety of airline navigation based upon GNSS signals, satellite-based augmentation systems have been developed to ensure the accuracy, integrity, availability, and continuity of user position estimates derived from GNSS measurements.
In the United States, the Wide Area Augmentation System (WAAS) of the Federal Aviation Administration (FAA) measures the ionospheric slant delay of signals propagating from Global Positioning System (GPS) satellites to multiple, dual-frequency receivers distributed across North America in a network of 38 reference stations. To allow the user to correct for the error due to ionospheric delay, WAAS derives from these measurements a vertical delay estimate at each ionospheric grid point (IGP) on a specified grid; this delay is designated the ionospheric grid delay (IGD) at that IGP. In addition, WAAS derives the grid ionospheric vertical error (GIVE) at each IGP from inflated and augmented values of the formal estimation error. GIVEs protect the user from the effects of delay estimation error resulting from ionospheric irregularity, both sampled and undersampled. The Ionospheric Slant TEC Analysis using GNSS-based Estimation (IonoSTAGE) software package is a Matlab platform for performing analysis and visualization of ionospheric slant total electron content (TEC) using measurements of GNSS. IonoSTAGE requires Matlab version 7.7 or later for execution.
IonoSTAGE provides three fundamental capabilities: (1) estimation of ionospheric slant TEC along arbitrary ray paths, based upon fits of historical GNSS data; (2) calculation of the WAAS ionospheric threat model; and (3) calculation of the IGDs and the GIVEs that are broadcast by WAAS for a given set of observational data. In addition, IonoSTAGE contains various scripts that serve as tools for analyzing the behavior of ionospheric TEC and for optimizing WAAS performance. IonoSTAGE computations have been used by the FAA to validate the ionospheric threat model for WAAS’s initial operating capability and for three successive upgrades.
This work was done by Lawrence C. Sparks, Anthony J. Mannucci, and Attila Komjathy of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Refer to NPO-43504.
This Brief includes a Technical Support Package (TSP).
Ionospheric Slant TEC Analysis Using GNSS-Based Estimation (IonoSTAGE)
(reference NPO-43504) is currently available for download from the TSP library.
Don't have an account?
Overview
The document titled "Technical Support Package for Ionospheric Slant TEC Analysis Using GNSS-Based Estimation (IonoSTAGE)" serves as a comprehensive guide to the IonoSTAGE system, which is designed for analyzing ionospheric conditions affecting satellite navigation systems. Developed under the auspices of NASA and the Federal Aviation Administration (FAA), this package outlines the methodologies and technologies employed in estimating total electron content (TEC) and assessing ionospheric threats.
The document is structured into several key sections, beginning with an introduction that provides an overview of IonoSTAGE and its significance in enhancing the accuracy of Global Navigation Satellite Systems (GNSS). It includes a detailed operation manual that covers essential topics such as installation procedures, document notation, and the estimation of total electron content, which is crucial for understanding ionospheric behavior.
A significant portion of the document is dedicated to the analysis of delay model accuracy and the computation of ionospheric threat models. This includes a quickstart guide for creating the Wide Area Augmentation System (WAAS) ionospheric threat model, along with an overview of the computation process. These models are vital for predicting and mitigating the effects of ionospheric disturbances on satellite signals, thereby improving navigation reliability.
The document also addresses broadcast data computation, options available within the IonoSTAGE framework, and procedures for reporting bugs, ensuring users can effectively utilize the system and contribute to its ongoing improvement. Acknowledgments highlight the collaborative efforts of researchers from the Jet Propulsion Laboratory, Stanford University, and the FAA, emphasizing the importance of interdisciplinary cooperation in advancing aerospace technology.
In addition to technical content, the document includes references for further reading and research, providing a pathway for users to explore related topics in ionospheric science and GNSS technology. The information is presented with a focus on practical applications, aiming to facilitate the transfer of technology and knowledge to users in various fields, including aviation and satellite communications.
Overall, the IonoSTAGE Technical Support Package is a vital resource for understanding and utilizing ionospheric analysis tools, contributing to the enhancement of satellite navigation systems and ensuring safer and more reliable aviation operations.
