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Terrain navigation has been used extensively by underwater vehicles the last decade. By comparing bathymetric measurements with a digital terrain model, it estimates a global position of the vehicle underwater, where Global Positioning System (GPS) signals are unavailable. With the increasing threat of GPS signal jammers and spoofers to marine vessels, GPS independent techniques are becoming more interesting for surface vessels as well. This paper explores the idea of using terrain navigation to detect GPS spoofing, and as a substitute position source during GPS jamming. The results from an experiment simulating GPS jamming of a surface vessel indicate the feasibility of such a system.

Cameras with filters in the focal plane provide the most compact solution for multispectral imaging. A small UAV can carry multiple such cameras, providing large area coverage rate at high spatial resolution. We investigate a camera concept where a patterned bandpass filter with six bands provides multiple interspersed recordings of all bands, enabling consistency checks for improved spectral integrity. A compact sensor payload has been built with multiple cameras and a data acquisition computer. Recorded imagery demonstrates the potential for large area coverage with good spectral integrity.