Global Navigation Satellite Systems (GNSSs) constitute afundamental element for the new Intelligent TransportSystems (ITSs) architecture. Due to the weak signal strengthof navigation signals, these applications are easily threatenedby interference sources. In particular, a serious threat for thesesystems is represented by the so called in-car jammers, cheapdevices able to obscure the navigation signal in a radius ofseveral hundreds of meters.The introduction of standards for vehicular ad-hoc networks(VANET) enables the exchange of data regarding detectedinterference events which can be used to enhance theawareness of interference sources, thus increasing thereliability of future ITSs.The main idea of this work is to make use of VANETs inorder to monitor and locate jammers representing a threat forvehicular commercial applications.In the first part of the paper the analytic description of thejammer localization problem is described. The technique hereadopted makes use of Differential Received Signal Strength(DRSS) measurements, which can be used to estimate thejammer position through a centralized maximum likelihoodmethod. The theoretical lower bond on the estimationaccuracy is also derived.In the second part of the paper the jammer localization isperformed with real measurements. The measurementcampaign carried out in the Galileo test range (GATE) inBerchtesgaden (Germany) is described in details, as well as theequipment used during the experiments and the set-up of thescenarios. Finally the results obtained from the post-processingof the measurements are presented.
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