Inside GNSS Media & Research

MAY-JUN 2018

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46 Inside GNSS M A Y / J U N E 2 0 1 8 www.insidegnss.com T he spoofing of GNSS signals is a controversial and divisive topic within the satellite navigation community. Some believe that spoof- ing is virtually infeasible, while other industry insiders believe that spoofing is actually trivial. Referring to Figure 1 , we present an example of a survey grade receiver, reporting that it is tracking each of L1 C/A, L2C, L1P(Y), L2P(Y) signals and generating a valid position solution in Norway while it is actually sitting on a desk in the Netherlands being fed a spoofed signal from an low-cost off-the- shelf "single frequency" soware defined radio. Contrary to other assertions, it was possible to perform this using only 12 megahertz of instantaneous broad- cast spectrum. is resulted in no mea- surable code-carrier divergence, nor was the spectrum quite as obviously dis- torted as has been suggested. Given that these apparently reasonable assumptions (that multi-frequency spoofing required a "multi-frequency" signal generator, and that spoofed signals will have obvi- ous imperfections), were demonstrated to be unfounded, then we should per- haps revise our assumption, and recon- sider our approach to the problem. Background e reliability of radionavigation equip- ment and the trust that can be placed in its correct functioning has become of increased importance as ever more aspects of modern infrastructure and civilian services have become dependent on it. Systems and techniques aimed at providing robustness or resilience against the malicious adversary come in a variety of forms: some are based on the augmentation of the receiver with sen- sors that are deemed inaccessible to the Recent presentations and publications have suggested that multi-frequency spoofing is infeasible using low-cost, off-the- shelf equipment, and that a good defense against any but well- funded and technically competent adversaries would be to use a multi-frequency capable survey grade receiver. The authors of this article wish to demonstrate that this is definitively false. MULTI-FREQUENC Y SPOOFING Challenging Our Assumptions About the Technical (In)Feasibility of Multi-Frequency Spoofing JAMES T. CURRAN EUROPEAN SPACE AGENCY AIDEN MORRISON SINTEF DIGITAL CILLIAN O'DRISCOLL CONSULTANT "It doesn't have to be pretty, it just has to work."

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