Long-range radar sensor for application in railway tunnels

This paper presents a feasibility study of a technique for measuring the distance between two trains following one another through a tunnel at a distance of several kilometers. A preliminary series of measurements was performed in the Channel Tunnel, between France and England, in order to characterize the propagation of high-frequency waves in such an environment, with the primary objective of showing the influence of frequency on received power. After a description of the main results of this first phase, a measurement system based on correlation techniques and employing pseudorandom sequences is presented. The last section of this paper reports the test results produced by the prototype; these results show promise in terms of range and measurement accuracy.