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Detecting meaconing attacks by analysing the clock bias of GNSS receivers

Marnach D., Mauw S., Martins M., Harpes C.

Artificial Satellites : Journal of Planetary Geodesy

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2013

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Vol. 48, No. 2

63--83

EN

Existing Global Navigation Satellite Systems offer no authentication of their satellite signals towards their civilian users. As a consequence, several types of GNSS-related attacks, including meaconing, may be performed and remain undetected. In the scope of the project “Developing a prototype of Localisation Assurance Service Provider”, which is funded by ESA and realised by the company itrust consulting and the University of Luxembourg, a methodology to visualise the beginnings and the ends of meaconing attacks by monitoring the clock bias of an attacked receiver over time was developed. This paper presents an algorithm that is based on this attack visualisation technique and is capable of detecting meaconing attacks automatically. Experiments in a controlled environment confirmed that the chosen methodology works properly. In one of these tests, for example, six meaconing attacks were Simulated by using a GNSS signal repeater. The algorithm was able to detect the beginnings and the ends of all six attacks, while resulting in no more than two false positives, even though the average delay introduced by the meaconing stations (repeater) was just 80 nanoseconds.

2

Numerical evaluation of sound attenuation provided by periodic structures

Martins M., Godinho L., Picado-Santos L.

Archives of Acoustics

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2013

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Vol. 38, No. 4

503--516

EN

The use of periodic structures as noise abatement devices has already been the object of considerable research seeking to understand its efficiency and see to what extent they can provide a functional solu- tion in mitigating noise from different sources. The specific case of sonic crystals consisting of different materials has received special attention in studying the influence of different variables on its acoustic performance. The present work seeks to contribute to a better understanding of the behavior of these structures by implementing an approach based on the numerical method of fundamental solutions (MFS) to model the acoustic behavior of two-dimensional sonic crystals. The MFS formulation proposed here is used to evaluate the performance of crystals composed of circular elements, studying the effect of varying dimen- sions and spacing of the crystal elements as well as their acoustic absorption in the sound attenuation provided by the global structure, in what concerns typical traffic noise sources, and establishing some broad indications for the use of those structures.

3

An energy harvesting circuit for self-powered sensors

Fernandes J. R., Martins M., Piedade M., Goncalves H.

International Journal of Microelectronics and Computer Science

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2011

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Vol. 2, nr 1

1-5

EN

In this work we present a prototype circuit to harvest energy from radio waves or through magnetic coupling based on a stack of full-wave rectifiers with transistors working on sub-threshold region. This circuit will use as an input a field-to-voltage converter capable of outputting a 200mV waveform and is able to self-start without any other energy sources. The circuit presented here is a proof of concept energy-harvesting circuit powering a low frequency ring oscillator which acts as the load. The circuit is designed, simulated and tested in a standard CMOS process, AMS CMOS 0.35 μm.