Small unmanned aerial vehicles (UAVs) are increasingly becoming a challenge for both civilian and military security. Even simple modifications of these inexpensive and widely available systems can create a serious threat which potentially causes major damage. Using signals from global navigation satellite system (GNSS), UAVs are able to operate over long distances and to find their target zone without remote control of a pilot. In this flight mode, radio direction finder cannot detect any transmitted signal. Typical countermeasures like RF jamming or Wi-Fi hacking become ineffective to stop the threat.

The DLR smart GPS spoofing approach is a promising technology for a cost-effective countermeasure against such autonomously flying Micro UAVs. Several dedicated devices must reliably interact to fulfil this task. The optical identification and position measurement of the UAVs was developed at the DLR Institute of Technical Physics. By optimizing the tracking processes and the laser ranging systems, even small and agile targets can be tracked. The measured position and flight data are forwarded to a GPS spoofing system developed by the DLR Institute of Communications and Navigation. The emitted GPS signal is modified in such a way that the UAV leaves its original flight trajectory and is redirected to a save one. Outside the protected area the UAV can be forced to ground without collateral damages. The feedback loop via the independent optical position measurement ensures that the desired flight trajectory is maintained. The basic functionalities of the smart GPS spoofing countermeasure were successfully demonstrated in realistic field tests. The optical setup and first results will be discussed.

Due to the growing number of small and agile unmanned aerial vehicles (UAVs), including consumer micro-drones, appropriate countermeasures technologies are necessary to protect public and military forces, to increase critical infrastructure resilience, and to secure exchange of data. Most of the countermeasure requires reliable up-to-date position information of the approaching threats. Beside precise determination of the angle-of-arrival laser pulse time-of-flight information is one of the promising technologies to measure the distance to a target. Laser Range Finders (LRF) are typically used for long ranges to large objects or slowly moving targets.

Within the scope of this paper we are going to show a method to enhance laser ranging capabilities to small and fastmoving UAV targets. Dealing with small and agile targets the primary limitation of many laser ranging systems is the reduced hit rate. The restricted torque of the pan-tilt-unit drives is not able to align the LRF in the direction of agile UAV targets in the sky. In this paper, we will present a method using an additionally piezo steering device to reduce this residual tracking error. To estimate the improvement, we are going to compare results under same conditions with and without the fast steering device. Experimental evaluations show an improvement of the LRF hit rate during high accelerations of micro UAVs. We present theoretical analysis and experimental results of UAV laser range measurements under realistic environmental conditions.