Étude du couplage d’une onde électromagnétique externe et d’une ligne de transmission aérienne non uniforme

In this paper, a flexible and efficient method for analyzing the electromagnetic field to nonuniform multiwire aerial lines coupling is proposed. This analysis in based upon the finite- difference time- domain (fdtd) algorithm. The transient responses of nonuniform lines excited by different waves obtained by this method are compared with those of Spice and literature. The good agreement between all the simulation results validates the proposed approach.     

Sur une expression des puissances d’une matrice et son application aux réseaux itérés

Annals of Telecommunications - Après une brève introduction, dans unepremière partie, l’auteur donne (I), de lapuissance d’une matrice d’ordre 2, une expression...     

L’apprentissage des modes de vie: une base indispensable au développement d’un habitat «intelligent»

The advent of new technologies in the field of data processing, electronics and wireless communications currently support the integration of essential functions for the provision of services tailored to the user needs at home. These services are destined to address two key societal demands, i.e., keeping health costs and energy costs under control. With this objective in mind, a number of research works involving various approaches have been conducted as those carried out atlaas for the purpose of integrating the habits and practices of home automation users. The principles under investigation rely on learning habits. Two examples of application using these concepts are presented through use of two home automation systems for a personalized behavioral monitoring of the elderly with a view to providing home care, and for the automatic management of thermal comfort. Promising results have been obtained and pave the way for efficient and cost effective systems that could be associated with other functions to contribute to the development of a truly «smart home».     

Présentation d’une technique 3D d’accélération de la recherche de rayons application aux télécommunications microcellulaires

Development of telecommunications using mobile phones requires the installation of many base stations (BTS) in order to cover the large number of cells which make up the network. Existing systems (GSM, DSC) use carrier frequencies within the microwave range. Ideally, operators should have simulation software to determine the position of BTS. This software would be used initially to determine the geometric configuration of the cells. The next step would be to optimise the radiation pattern of each BTS antenna. In this article we present a method for determining radioelectric coverage based on image theory adapted to the problem, which is more accurate and less time-consuming than conventional methods.     

Étude du comportement d’une boucle de Costas en modulation MAQ 16 en présence d’évanouissements sélectifs

This paper gives the variance of the phase recovered by a conventional quadriphase Costas loop in 16 Qam modulation in the presence of a selective fading, represented as a three rays simplified model. The power spectral density of the phase error is computed using a spectral estimation technique. The phase error variance is evaluated for different values of the fade depth, the location of the maximum attenuation in the frequency band and the delay of the reflected ray. Finally the relation between the performance degradation and phase noise is given, assuming a gaussian p.d.f. of the phase error.     

Étude théorique et expérimentale d’une modulation simplifiée par déplacement de fréquence d’indice 1/2 à phase continue

The minimum shift keying modulation (MSK)to which a lot of recent publications have been done,presents some advantage about linear and non-linear distortions towards common 2 or 4 Phase Shift Keying (PSK)modulations. The simplified MSK modulation described in this paper is obtained by linear filtering of a coherent 2 phase shift keying modulation. Then the demodulator can be implemented with a matched filter followed by a coherent demodulator using only one carrier recovery circuit. In the first part of this paper, the modulator and the demodulator are described. After, some theorical results in the presence of noise and other impairments are given. In CCETT laboratories at Rennes, a modem has been realized at a data rate of 2,048 Mbit/s and performs at 0,8 dB of the theoretical results.     

Le dépôt et la cristallisation d’une couche mince organique au moyen d’un faisceau laser

An original technique to prepare thin organic films is presented. These materials are of interest for integrated optics. Films are formed after scanning of compacted powder of pom (3-methyl 4-nitropyridine 1-oxyd) with continuous wave Ar ion laser. The action of the laser is to evaporate organic molecules from the compact and cristallize them on a supporting substrate. The developments and limits of this technique are discussed.     

MobileJMS: une solution globale d’adaptation des applications nomades

Middleware technologies have emerged as a key element of future mobile systems. In this paper, we argue that Message Oriented Middleware Systems (MOMS) provides a valuable solution to nomadic environment issues. They are characterized by a communication style allowing a strong decoupling between distributed entities. The first part describes MobileJMS, a mom system characterized by communication adaptability and context-awareness. Its communication module is based on components which can be plugged and configured dynamically to deal with various events such as bandwidth variation or frequent disconnections. The second part is related to an overall adaptation model that makes adaptation decisions by considering user preferences, application requirements and execution context state. The key function of the model is the selection of the most appropriate policy to the current context.     

Evaluation des performances du réseau en anneau AMBRE pour distribution d’abonnés

ambre is an integrated services digital loop-like network for public local communication. Each communication is a sequence of fixed-length packets separated by fixed-length silences. Performance evaluation is carried through in terms of access-time and transport delays with emphasis on inter packet delay fluctuations.