Integrated Galileo Reference Infrastructure and technology development for height modernization

Last Updated: 13/06/2024 06:54     Created at: 13/06/2024 06:54

Final Presentation of NAVISP Project EL3-024 now available:

On Tuesday, June 11th, 2024, the Lechner Knowledge Center  presented the results of the NAVISP EL3-024 project " Integrated Galileo Reference Infrastructure and technology development for height modernization (INGRIM)". 

The use of multi-GNSS positioning, which leverages a multitude of satellite systems and the availability of numerous satellites, is increasingly prevalent in traditional navigation, geodetic applications, mass market products, and scientific monitoring. Despite its extensive use, GNSS positioning is still underrepresented in surveying for determining physical heights with <1 cm accuracy. Current classical levelling technology requires a dedicated, dense, and often unfavourably distributed set of reference benchmarks. Maintaining this system is costly, labour-intensive, and time-consuming. Furthermore, the static network needs to be updated every few decades, creating uncertainty about height changes between measurement epochs. In Hungary, the situation is particularly challenging. The long-anticipated update to the levelling network (EOMA) has only been partially completed, and its continuation remains uncertain. Partial re-measurements have revealed significant systematic height changes, rendering EOMA unreliable as a height reference.

In this context, the project aimed to establish a new height reference infrastructure by transitioning from traditional levelling benchmarks to multi-technique stations with expanded application opportunities. By leveraging multi-GNSS, including Galileo, and InSAR from Earth observation technologies, the project sought to create a robust and versatile height reference system.

A key objective was to define and implement a semi-kinematic height reference. This involved developing a virtual height reference surface for converting spatial coordinates into local frames, shifting from a static world view to a semi-kinematic height reference that models ground motion from a given reference epoch. This approach provided a more dynamic and accurate height reference system.

The project also proposed recommendations for transitioning from traditional levelling to GNSS heightening in the medium term. To achieve this, two comprehensive campaigns with in-situ measurements were conducted. The first campaign focused on static measurements, covering the entire pilot area using four multi-GNSS equipment setups and over 50 benchmarks. Measurements were taken using a centred antenna setup with 45-minute measurement periods, followed by RINEX postprocessing. The second campaign, the RTK campaign, included 18 points in Szeged city, with standard 3-minute RTK sessions repeated for verification. Eccentric measurements were conducted to validate the superiority of multi-GNSS, including Galileo, and to assess environmental dependency ("free" horizon vs. covered environment). 

At the end of the project, Lechner Knowledge Center successfully implemented a new, modernized, space technology-supported height reference system. All hardware elements became operational, supporting geodetic practice and providing a resilient background for multi-GNSS RTK positioning. Extensive testing proved the solution's reliability.  The approach, demonstrated through this successful NAVISP project,  has been  accepted for implementation at national level and a national-scale extension has been  initiated, expected to be completed within three years.

The project was part of NAVISP Element 3, aiming to support national PNT strategies by providing support per country and possibly per domain for the development and promotion of products, applications and services based on PNT systems to foster national and international cooperation.

The slides are accessible here.