Development of the compact maintenance system for railway signalling equipment using the multiplex system and FFT analysis

The authors have developed a compact maintenance system that can be mounted under the floor plate of a commercial train. The new system shares a single sensor to measure ground coils for ATS (automatic train stop), track circuits, and electronic train detectors for level crossings. Accordingly it doesn´t take much space when installed under the floor plate of a train. It refines the measuring method. The primary coil of the sensor can transmit multi-carrier wave simultaneously, and its secondary coil can receive mixed multi-carrier wave induced by coupling with ground coils for ATS. This system calculates f_o and Q of ground coils by FFT analyzing mixed multi carrier wave using a digital signal processor (DSP). Using simultaneous multi carrier wave and digital signal processing, it can measure signalling equipment precisely, if a train runs at high speed. Moreover, we can analyze the collected data easily and express the results of measurement graphically by the wayside analysis system. In this paper, we explain the new method of measuring signalling equipment, construction and function of this system, and report on the results of its field test