Global Navigation Satellite Systems (GNSSs) have become a critical part of the infrastructure of modern society. Radio interference can introduce position or timing errors in systems that use GNSS or, in a worst-case scenario, block the reception of GNSS signals in full. Part of this critical infrastructure is, among others, power plants, banks, and transport. Interference of GNSS signals could originate from nature, such as solar activity or ionospheric effects. Other interference could originate from unintentional sources (e.g., radio signals from a malfunctioning radio tower) or intentional sources such as a jamming or spoofing device. The latter is what this thesis will focus on. This thesis consists of two parts. The first part is about jamming and elaborates on the impact of seven different forms of jamming on two types of GNSS receivers, a time-worn receiver and a cuttingedge receiver. The cutting-edge receiver has as option to turn on Interference Mitigation (IM). The performance of both receivers is the roughly the same in case the IM is turned off on the cutting-edge receiver. However, when the IM is turned on the cutting-edge receiver clearly is more resillient to the jamming signals. In the second part of the thesis various types of spoofing are discussed. Due to time and hardware restrictions it was not possible to perform synchronous spoofing, which is an advanced form of spoofing. Instead, various concepts are discussed that describe how synchronous spoofing could be achieved.

Due to the advancements made in the GPS technology, a new smartphone RTK-GPS system can be used to do measurements with high accuracy, while the equipment is much cheaper than before. In addition, the equipment is relatively small. This makes the system useful for measuring the velocity of the water currents with the use of a drifter. Currently there are no cheap drifters available in which the RTK-GPS smartphone system is integrated. Therefore, such a drifter must be designed. The design needed to be compact, lightweight, watertight and must be designed for use in rivers and small streams. Concept drifters have been made to test the shape, dimensions, material and watertightness of different designs. Using the obtained knowledge, a final drifter design for the bachelor thesis was made, which met most of the requirements for a working design. All the steps taken in the design process of the drifter are described in the report. Further steps in the process of designing a drifter with an integrated smartphone RTK-GPS system have been described in the conclusion of the report.

Estimating groundwater levels spatially using time series analysis. With time series analysis a response function of an observation well is determined. The response function is used to calibrate a conceptual groundwater model. This conceptual model is used to estimate groundwater levels in an area.

From this study can be concluded that using drones equipped with cameras a 3D model van be created of an incident on the rail. From the recordings, a 3D model van be made using photogrammetry. In this model it is possible to measure post distances with an estimated error of less than 1 centimeter. The distances between the laser scanner point cloud and the point cloud created with the drone are in 78% of cases smaller or equal to two centimeters. In order to further reduce the distances between the point clouds more photos from the bottom of the train.