The vulnerability of Global Navigation Satellite Systems along with potential mitigation strategies has been the subject of discussion in many industry segments where the delivery of precise positioning or timing is of high importance. This paper provides an assessment of the difficulties and issues that currently exist in assessing the robustness of commercial GNSS devices against threats (including RF Interference, solar weather effects and Spoofing). Real world threats against GNSS are reviewed along with the expected evolution of threats as criminals seek to obtain financial gain from the use of jamming and spoofing to induce malfunctions in sophisticated tracking equipment. The paper shows that it is essential to develop a risk assessment framework for Positioning Navigation and Timing (PNT) systems so that the robustness of the system can be assessed against real-world theat vectors-and the most appropriate (and cost effective) means of mitigation can be selected.

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