Location and communication using cooperative RADAR system dedicated to guided transports

Abstract Nowadays, automated systems and sensors are being developed to improve reliability, safety and offer new exploitation modes in guided transports. In maritime and airway domains, many intelligent systems are used for simultaneous location and exchange of information. However, in guided transports domain, no system is nowadays able to ensure the both functionalities. This paper presents a new system called CODIBDT (communication, detection and identification of broken-down trains) allowing multi-user access and combining the two main functionalities, location and high data rate communication, using a cooperative collision avoidance radar transponder inside targets (train, metro, etc.). The proposed system is made of a couple of microwave transmitting and receiving equipments fixed on each train, one ahead and other behind. The sensor uses a matched digital correlation receiver in order to detect the position, compute the distance towards the preceding vehicle and get its status and identification. This radar exploits two frequencies, 2.2 GHz for transmitting and 2.4 GHz for receiving. The distance to the targets is measured, in real time, with a resolution of 3 m in a range of 800 m in tunnel and 500 m in open space using a transmitted power about 600 mW. To allow multi-user access and to combine the two main functionalities, two original multiplexing methods called SSS2 (sequential spreading spectrum technique) and CPM (code position modulation) are performed. This study is focused on the comparison between the two methods in terms of bit error rate, degree of complexity and data rate.