Characterize the signals (based on open literature) of several space-based transmitters of opportunity and analyse these in terms of performances for passive radar applications (e.g., detection range, coverage, resolution, etc.). Evaluate the signal characterisation of selected transmitters of opportunity by performing real-world measurements of the direct signals (in collaboration with the Radar Technology department of TNO) in terms of performances for passive radar applications (e.g., ambiguity function). Design a passive radar system architecture based on space-based transmitters of opportunity.