For safe navigation, maritime transportation relies heavily on accurate positioning and timing information provided by Global Navigation Satellite Systems (GNSS), such as the American GPS or European Galileo. The availability of this information is especially crucial in challenging conditions, such as poor visibility, congested waters, or port areas. Radio frequency interference, whether intentional (jamming and spoofing) or unintentional, can disrupt the relatively weak GNSS satellite signals, leading to navigation errors, delays, or even accidents. To maintain precise navigation and enhance safety, efficiency, and security at sea, interference-resistant GNSS receivers serve as a key solution, as envisioned by the IMO's e-navigation concept.
The Institute of Communications and Navigation of DLR has developed a prototype of an interference-resistant GNSS receiver called GALANT, which utilizes adaptive antenna arrays. This receiver can adaptively shape its reception pattern based on the observed signal environment to improve the reception of GNSS satellite signals while mitigating unwanted signals by placing "nulls" in the direction of the interference. The use of such a receiver significantly reduces the impact of jamming and spoofing signals. Consequently, the positioning and timing information remains undistorted and continuously available for safe ship navigation.
Additionally, the GNSS array receiver enables the estimation of the directions from which interference signals arrive. This allows for the localization of interference sources and enables efficient countermeasures in traffic management. Several versions of the receiver at Technology Readiness Level (TRL) of 4-5 are available, allowing for the validation of the technology in real-world environments. Various DLR antenna array designs, developed in-house at different levels of miniaturization, are also available. One version of the GALANT receiver operates similarly to a Controlled Reception Pattern Antenna (CRPA), a system that replaces conventional GNSS antennas and is compatible with legacy single-antenna GNSS receivers. This version is currently being commercialized by Lange Electronic GmbH. For more details, please see the description of the CRPA-Guard system at https://www.lange-electronic.com/de/gnss-resilienz.
Principle of interference mitigation with an adaptive antenna array
