Advantages of a Robust Multi-Antenna GNSS Receiver in UAV Flight Jamming Scenarios

Abstract

The multi-antenna Global Navigation Satellite System (GNSS) receiver GALileo ANTenna (GALANT) has been developed at German Aerospace Center (DLR) since several years. Recently, effort has been spent to miniaturize the antennas and digital processing system in order to enable applications in the field of Unmanned Aerial Vehicle (UAV) navigation for example. In addition, array processing technologies have been further improved for this kind of application. This publication focuses on the conduction of flight test of the complete system and the therein occurring advantages towards a commercial receiver in difficult navigation scenarios like under the influence of jamming. The flight experiments are divided into two parts. Firstly, it is investigated how the different receivers react to corresponding jamming from the ground while the receiver is not moving, but is hovering close to the ground. During this experiment, the jamming power is increased step by step. The reference receiver goes into saturation, gradually loses all satellites, the position accuracy drops and finally no valid Position/Velocity/Timing (PVT) can be computed. In contrast, the GALANT receiver detects the interference and suppresses it appropriately based on spatial signal processing techniques. In the second part of the experiments, it is investigated how jamming signals emitted from ground affect the receiver during real flight scenarios. A static and directional jammer is set up and the UAV flies a trajectory passing multiple times through the beam. Interestingly the reference receiver does not only lose all satellites in track, like expected from the first experiment, but computes a false position increasingly diverging from ground truth before and after the total loss. The deviation of position is in the range of multiple hundred meters. The GALANT receiver is able to keep most of the satellites in track, and computes a continuous position with negligible deviation. The flight experiments conducted show that it is reasonable to protect UAVs appropriately against interference such as jamming. The tests also show that techniques, such as those presented, can be an effective solution to the stated problems. The developed robust, multi-antenna receiver outperformed the corresponding comparison receiver in the presented areas.