Broadcast of Pseudorange and Carrier-Phase in MT23 (By Indra)
This work proposes broadcasting pseudorange (PRR) and carrier-phase (RCI) residuals instead of full measurements.
The approach significantly reduces bandwidth usage in Message Type 23 (MT23).
Smoothing and leveling techniques are detailed, along with their impact on ionospheric delay estimation and positioning accuracy.

AUGMENTED GEOMETRY SCREENING USING EUROPEAN GNSS (By Indra)
This document proposes an enhanced geometry screening method for European SBAS using multi-constellation GNSS data. It aims to protect aircraft from ionospheric gradients by adjusting integrity parameters in simulated worst-case scenarios and introduces a local algorithm to estimate ionospheric delays based on dual-frequency measurements and ICAO threat models.

GAST E Ranging Source Integrity (By Indra – June 2024)

This presentation, part of the EDGAR project, outlines integrity monitoring requirements for ranging sources in DFMC GBAS, focusing on GAST E operations. It addresses how airborne geometry screening and ionospheric gradient mitigation can be optimized using dual constellations and multi-frequency data. The goal is to improve performance and flexibility for CAT III approaches while managing stricter threat models and maintaining compatibility with existing aircraft.

Extension of DUFMAN models in support of DFMC GBAS standardization activities (By DLR – 13Th & 17Th May 2025)

The presentation addresses the extension of DUFMAN models to enhance the accuracy of satellite-based landing systems for DFMC GBAS.
New smoothing methods and calibration of multipath and antenna errors are being studied.
This work lays the foundation for future, more robust and safer air navigation standards.

AUGMENTED GEOMETRY SCREENING USING EUROPEAN GNSS (By Indra – June 2024)

This document proposes an enhanced geometry screening method for European SBAS using multi-constellation GNSS data. It aims to protect aircraft from ionospheric gradients by adjusting integrity parameters in simulated worst-case scenarios and introduces a local algorithm to estimate ionospheric delays based on dual-frequency measurements and ICAO threat models.

Update airborne Multipath Models for Dual – Frequency Mutli-Constellation GBAS (By DLR – September 2024)

This presentation introduces updated airborne multipath models for DFMC GBAS systems, considering smoothing times of up to 600 seconds. Data from the DUFMAN project was reprocessed with improved antenna calibration and enhanced cycle slip detection. The new models provide a more accurate representation of error, supporting future standardization in aviation navigation.

Proposed changes to MT23 (By Indra – Decembre 24)

This presentation proposes changes to the MT23 message in DFMC GBAS systems, focusing on broadcasting carrier phase measurements without integer ambiguities. A solution using residual carrier phase increments is presented, enabling reduced bit usage. The implications on ionospheric delay estimation and potential implementation in the ground subsystem are also discussed.

Broadcast of pseudorange and Carrier-pase in MT23 (By Indra - February 2025)
The presentation proposes broadcasting pseudorange residuals (PRR) and residual carrier phase increments (RCI) in MT23 instead of full-resolution measurements. This approach significantly reduces bandwidth while preserving accuracy for ionospheric delay estimation and Dfree smoothing. Results show that using PRR and RCI yields performance equivalent to full-resolution data.

Gauss-Markov Models for Over-Bounding Carrier Smoothed Code Errors (By DLR – March 2025)

This work proposes multi-dimensional Gauss-Markov (GM) models to over-bound Carrier Smoothed Code (CSC) errors in GNSS airborne applications. It models pseudorange errors as a combination of multipath, white noise, and bias, providing accurate bounding during both transient and steady-state filter phases.
Preliminary results show promising performance for airborne use, with potential applications in ground systems and advanced GNSS services.

GBAS Ground Antenna (Error) Characterization (By DLR – May 2025)
This study analyzes how GBAS ground antennas affect navigation signal quality. It found the antennas perform very consistently, though signals at certain frequencies (like L5/E5a) show slightly more error.
Future work will use digital simulations to predict how each antenna behaves once installed on-site.