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Environmental characterization for track signaling
Problem
Rail signalling equipment may be perturbed by electromagnetic noise. If the ambient electromagnetic noise or the EMI generated by rail vehicles is too high, then it may infer with the operation of rail signalling equipment. In this case study excessive electromagnetic noise was detected in the on-board signalling equipment. In addition, track-side signalling equipment and balises also detected false track occupation.
Aim
To determine the source of electromagnetic noise interfering with trackside equipment.
• Electromagnetic field level measurements
• Evaluation of on-board signaling equipment
• Track signal quality assessment
Instrumentation/ measurement
The input voltage received by the on-board signalling equipment was recorded in order to evaluate the magnitude of the interference signal detected by the on-board signalling antenna.
Results
Despite the noise in the signal, the wayside signal could be distinguished from the on-board equipment on the majority of occasions. As the system is so sensitive, the track signal was recorded with misleading information that in some cases produced false signal decoding. Furthermore, the signal level was out of specification in some locations (infrastructure problem) and the on-board equipment was unable to decode the rail message correctly.
Actions
• Software modification to adjust sensitivity option.
• Rail signal adjustment to meet the specifications.
• Rail signal adjustment to meet the specifications.
