Glossary

Crosstalk. Detrimental phenomenon whereby a signal intentionally injected in a transmission channel produces an unwanted effect in another transmission channel. Crosstalk occurs notably in interconnections, for instance in the circuits of telecommunication networks, the cables of local area networks, the traces of printed circuit boards, on-chip interconnects, etc. In the case where crosstalk takes place in a multiconductor interconnection, crosstalk which occurs between transmission channels created in this interconnection is referred to as internal crosstalk, while crosstalk which occurs between a transmission channel created in this interconnection and other circuits is referred to as external crosstalk. In the case of internal crosstalk, we must also distinguish the crosstalk voltages or currents which occur at the end where the signal source is connected, referred to as near-end crosstalk, from the crosstalk voltages or currents which occur at the opposite end, referred to as far-end crosstalk. This is because the properties of near-end crosstalk and far-end crosstalk differ.
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DSP. DSP stands for "digital signal processing". The signals are processed in order to extract or to modify the information contained in them, or to adapt them to the means of transmission or to the means of information storage. The digital signal processing consists of processing a signal made of a set of discrete numbers (digital signal). Digital processing of an analog signal consists basically of three steps: conversion of the analog signal into a digital form, processing of the digital version, and finally conversion of the processed digital signal back into an analog form. DSP also stands for "digital signal processor". It is a microprocessor which architecture is optimized for the digital signal processing.
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Echo. Detrimental phenomenon whereby a signal propagating in a given direction, in one of the transmission channels, produces an unwanted effect on the same transmission channel, propagating in the opposite direction. In a multiconductor interconnection, we distinguish between echo and the more general concept of reflection because reflections occuring for instance at an end of the interconnection may be responsible for echo and/or internal crosstalk.
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Electromagnetic compatibility. See EMC.

EMC. EMC stands for "electromagnetic compatibility". The electromagnetic compatibility is the ability of a device, equipment or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to anything in that environment. By extension, EMC also designate the scientific field of studying and understanding the EMC of items, and the technical field concerned with obtaining the EMC. Equipments and systems are often subject to mandatory EMC requirements. In Europe, most legal requirements are related to the application of the 89/336/EEC directive, also called EMC directive. The technical requirements are expressed in basic EMC standards from the Cenelec, and in product standards. Excem has a lot of activity in engineering for EMC, special measurements for EMC, problem solving for meeting EMC specifications, in providing instruments for electromagnetic measurements, and in editing software for EMC predictions. Excem has also an extensive experience in the EMC of installations, the protection against lightning and electromagnetic pulses, and the manufacturing and installation of special suppressors or filters.
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Electromagnetic pulse. See EMP.

EMP. EMP stands for "electromagnetic pulse". Electromagnetic pulses of large amplitudes occur during lightning, close to high voltage switch gear during switching, or because of nuclear explosions (the so-called NEMP or nuclear electromagnetic pulse). Protection against EMP is one of the suject of EMC.
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SARL. The French "SARL" or "société à responsabilité limitée" is similar to the English "private company". The shares are called "parts sociales". The right to transfer the parts sociales is restricted. The head of a SARL is a "Gérant" (Manager).
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Société par actions simplifiée. The French "société par actions simplifiée" (SAS) is more or less equivalent to the "limited company" of English law or to a limited liability company under United States law. The head of a société par actions simplifiée is its "Président" (Chairman or President). However, this company, unlike the "société anonyme", does not have a board. The Président is also responsible for the operation of the company. The company may also have a "Directeur Général" (General manager or CEO), who has the same authority as the Président with respect to third parties.
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