Method for detecting jamming signals superimposed on a radio communication application to the surveillance of railway environments

The Railroad network composed of stations, depots, tracks, trains... constitutes one of the major critical infrastructures in industrial countries. Because of this criticality and of its large deployment, studying the resilience of the railway network regarding intentional electromagnetic interferences (IEMI) is important. This paper considers IEMIs generated by low power electromagnetic jammers operated in railway environments. Jammers can be used to disturb or even interrupt the radio communications of railway operators. This paper concentrates on methods which were developed and evaluated to detect jamming signals appearing in a radio channel while a radio communication is running. Several supervised detection methods were tested. We concentrate and detail one of these methods which is derived from conventional EMC measurements. We present two hardware and software implementations using successively a real time analyzer and a prototype equipment built in the laboratory. Jamming signals are injected on a cellular phone radio communication and the results are analyzed. We obtain that the jamming signals are readily detected and some of their radiofrequency characteristics extracted.