Jean Rioult

Study of the Susceptibility of the GSM-R Communications Face to the Electromagnetic Interferences of the Rail Environment

The Global System for Mobile Communications-Railway (GSM-R) system is currently deployed in Europe in order to ensure the interoperability of the high-speed trains. Knowing that data related to control and command will be transmitted to trains through this communication system, the immunity of the GSM-R system against electromagnetic disturbances on board trains has to be certified. After a background about the GSM-R communication system, we will present in detail the typical disturbances that can affect this system in the railway environment. Significant differences between these disturbances and the test signals defined in the current European electromagnetic compatibility standards will be highlighted. The criteria that can be employed to evaluate the immunity of the GSM-R transmissions will then be discussed. Finally, new test signals and immunity test bench will be presented in order to expose the GSM-R transmissions to noise scenarios representative of the railway environment. Different immunity results will be presented and analyzed.

Novel electromagnetic field measuring instrument with real-time visualization

Nowadays, a wide variety of terminals are proposed to nomadic users. Generally, these terminals provide wireless communication operating at frequencies between one and a few GHz. For technical reasons, including multiple access to the communication channel and battery autonomy, these terminals transmit only during very short periods i.e. transmission bursts. For a direct observation of certain characteristics of the transmitted signals radiated by such terminals, only a few measurement setups exist. This paper proposes such a novel real-time 3D electromagnetic field measurement instrument with direct visualization. The prototype used for validation is based on an array of probes regularly attached on a non conductive rigid loop which is put into fast rotation around the terminal under test.

On the use of 3-D TEM cells for total radiated power measurements

Three-dimensional (3-D) TEM cells offer new issues in EMC immunity and emission testing, where the question of orienting the object under test is no longer raised. This paper starts by presenting the general concept of 3-D TEM cells and hybrid chambers followed by one of the first applications in measuring the total radiated power of devices under test. After a short background on emission measurements in TEM and GTEM cells, the second part of this paper considers a practical industrial case where the total radiated power of an electronic equipment is measured in a 3-D TEM prototype cell, and the results compared to those of TEM and GTEM cells. Finally, the repeatability and reproducibility between TEM, GTEM and 3-D TEM cells is studied and discussed.

On the use of three-dimensional TEM cells for total radiated power measurements

Three-dimensional TEM cells offer new issues in EMC immunity and emission testing, where the question of orienting the object under test is no longer raised. This paper starts by presenting the general concept of 3-D TEM cells and hybrid chambers followed by one of the first applications in measuring the total radiated power of devices under test. After a short background on emission measurements in TEM and GTEM cells, the second part of this paper considers a practical industrial case where the total radiated power of an electronic equipment is measured in a 3-D TEM prototype cell, and the results compared to those of TEM and GTEM cells. Finally, the repeatability and reproducibility between TEM, GTEM and 3-D TEM cells is studied and discussed.

Analysis of electromagnetic pollution radiated due to embedded 802.11a/b/g equipments both inside and outside railway vehicles

This paper deals with the modelling of a railway vehicle to calculate the electromagnetic field distribution inside and outside the vehicle at 2.45 GHz and 5 GHz. Our objective is to evaluate the electromagnetic (EM) pollution induced outside the vehicle due to onboard Wi-Fi networks. Experimentations have been performed on a railway vehicle both with CW and Wi-Fi standard transmitter-receiver systems. A geometrical model has been defined for the numerical simulations of the vehicle body retaining only the predominant structural parts in the electromagnetic phenomena. This work should then allow to analyse via simulation, the optimal configuration of the onboard Wi-Fi devices in order to reduce the EM field outside the vehicle which can prove to be a source of pollution for other Wi-Fi networks.

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.

Time-frequency processing adapted for the different electromagnetic compatibility issues in the railway domain

The railway environment is very rich in terms of electromagnetic disturbances. The variety of the transient and permanent interferences and the current evolution of the communication and signaling railway systems require the adaptation of EMC railway standards. In particular, standardized emission measurement methodologies are not fully adapted to measure transient interferences which can significantly affect new railway signaling and communication systems. In this paper, we study a new time-frequency processing specifically designed for railway EMC issues, which could be implemented on real time spectrum analyzers. A flexible methodology is proposed offering an optimum analysis in relation with the technical specifications of the different railway signaling and communication systems.

A time-domain diagnostic method for emission measurements in TEM cells

Emission testing techniques using TEM cells are currently based on power measurements at their port(s) in the frequency-domain. Spectrum measurements do not give directly phase information and therefore only offer partial information on the electromagnetic emission of an equipment under test (EUT) such as the total radiated power. This drawback often leads to difficulties in interpreting the emission results in order to determine precisely the origins of radiation within the EUT and to improve its design. This paper presents a new diagnostic method based on time-domain emission measurements using TEM cells in order to determine the origins of radiation within an EUT Unlike spectrum measurements, time-domain measurements can offer full information on radiation, and by correlation with the known currents in the EUT, can help pin-pointing the contributors within the EUT responsible of the highest emission levels.

Time frequency processing dedicated to electromagnetic compatibility issues in the railway domain

The railway environment is characterized by various electromagnetic interferences (EMI) due to the large number of EMIs sources. In parallel, due to the variety of vulnerable systems (location, signalization, communication…) embedded or in the train vicinity, different techniques are required to study EMC issues. This work is focused on time-frequency tool adapted to the analysis of different EMI, whereas their significant differences in terms of frequency, power and time characteristics. Such tools could be integrated in real time spectrum analyzers in order to optimize measurements for railway EMC issues.