ARS Advances in Radio Science ARS Adv. Radio Sci. 1684-9973 Copernicus Publications Göttingen, Germany 10.5194/ars-10-39-2012 A cooperative transponder system for improved traffic safety, localizing road users in the 5 GHz band Schaffer B. 1 Kalverkamp G. 1 Chaabane M. 1 Biebl E. M. 1 Fachgebiet Höchstfrequenztechnik, Technische Universität München, Munich, Germany 18 09 2012 10 39 44 Copyright: © 2012 B. Schaffer et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://ars.copernicus.org/articles/10/39/2012/ars-10-39-2012.html The full text article is available as a PDF file from https://ars.copernicus.org/articles/10/39/2012/ars-10-39-2012.pdf

We present a multi-user cooperative mobile transponder system which enables cars to localize pedestrians, bicyclists and other road users in order to improve traffic safety. The system operates at a center frequency of 5.768 GHz, offering the ability to test precision localization technology at frequencies close to the newly designated automotive safety related bands around 5.9 GHz. By carrying out a roundtrip time of flight measurement, the sensor can determine the distance from the onboard localization unit of a car to a road user who is equipped with an active transponder, employing the idea of a secondary radar and pulse compression. The onboard unit sends out a pseudo noise coded interrogation pulse, which is answered by one or more transponders after a short waiting time. Each transponder uses a different waiting time in order to allow for time division multiple access. We present the system setup as well as range measurement results, achieving an accuracy up to centimeters for the distance measurement and a range in the order of hundred meters. We also discuss the effect of clock drift and offset on distance accuracy for different waiting times and show how the system can be improved to further increase precision in a multiuser environment.

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