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Les principaux résultats de recherche présentés dans cette thèse de Doctorat concernent la proposition de nouvelles méthodologies de spécifications et de dimensionnement ainsi que des techniques de mise en œuvre de structures de filtrage et de conception d'architectures matérielles reconfigurables pour la sélection numérique des canaux radio dans un contexte de réception multistandard. Les résultats obtenus à l'issue de cette thèse constituent une contribution à un nouvel axe de recherche qui vise à développer de nouvelles technologies pour des équipements radio flexibles, multi-service, multi-standards, multi-bandes, re-configurables mais tout en limitant la complexité de traitement et d'implantation matérielle en vue de réduire d'avantage l'encombrement des équipements portables ainsi que leur consommation d'énergie. Notre première étape d'étude a concerné la définition de structure et de méthode de dimensionnement d'un récepteur radio à conversion directe doté de fonctionnalités large bande et multi-bande. Une méthode a aussi été établie pour déterminer les spécifications des étages de sélection des canaux en tenant compte de la structure de filtrage en cascade, des profils des signaux et interférents radio ainsi que des effets de repliement de spectre. Les résultats de synthèse sur FPGA ont permis de mettre en évidence les performances en terme de qualité de filtrage et d'optimisation des ressources d'implantation matérielle.

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The problem of this study was to determine whether using radio communication can facilitate learning in counseling practicums. This study had four purposes: 1. To determine whether the use of radio communication would be effective in providing positive reinforcement to the counselor during counseling sessions. 2. To determine whether the use of radio communication would be effective in enhancing the learning of facilitative responses by counselors in practicum situations. 3. To determine the effect of positive reinforcement on the student counselors' performance. 4. To provide information that might be beneficial with regard to future research involving the use of radio communication in counselor training.

Thesis (Masters Diploma( Technology)) --Cape Technikon, Cape Town, 1989 / Soekor's exploration programme has moved totally offshore and expanded greatly in the past few years. Use of computers necessitated the exchange of data between offshore and land installations. At the same time the exploration programme is moving further offshore While the coastal. stations of the Post & Telecommunications can not handle the volume of traffic that the oil drills present nor the data modes. A study of the transmission requirements revealed that a minimum of one voice channel per drill must be available at all times, While Some 20M byte of data per oil drill per year will be transmitted. Facsimile will be needed at times, also as a back-up for the data systems. A study of publications revealed that only five of the eleven methods studied where viable, namely VHF-EM, satellite, HF-telephony, HF-teleprinter and HF-data. These possibilities as well as their practical implementation were studied in depth. The effect of the atmospheric conditions on the propagation of VHF-signals around the coastline was studied and 17 sites identified and evaluated from the mouth of the Orange River to Port Elizabeth in respect of coverage, accessibility, facilities and cost. INMARSAT facilities and costs were evaluated as well as HF-systems. Finally a system was designed consisting of HF-telephony, separate "packet" HF radio data system, satellite telephony back-up and satellite high speed data as well as a limited VHF system. The entire system is complemented by marine telephony and telegraphy equipment. On-going system guidance in the form of propagation predictions is provided. Some existing equipment was used, While R950 000 has been spent to date on additional equipment.

Denna studie har undersökt möjligheten att implementera ett trådlöst kommunikationssystem i en ugnsmiljö. Den trådlösa kommunikationstekniken som har använts är av standarden IEEE 802.15.4. För denna undersökning har ett trådlöst mätsystem för temperatur konstruerats. För att hålla nere temperaturen på detta mätsystem har kapslingsmaterialen keramik och glasull använts. Resultatet av mätningarna visar att kvalitén på radiokommunikationen kan förväntas vara god för de testade förhållande med kapsling och en temperatur upp till 200 grader. För de testade förhållandena i ugnsmiljön visar mätresultat att positionering är av större betydelse än värmeutvecklingen och kapslingen. / This study has explored the possibility to implement a wireless communication system in an ovenenvironment. For this exploration a wireless measurement system for temperature have beenconstructed. The technology of use is a radio communication system with the standard IEEE 802.15.4. The high temperature in the oven environment is kept down at the electronic by using anenclosure. The enclosure material that have been examined is a ceramic layer and a fibreglasslayer. The result of this study shows that the quality of the radio communication for the tested enclosureis expected to be good for temperatures up to 200 degrees. For the test cases the relation betweenthe radio module’s positioning is more important than the increase of temperature and the use ofan enclosure.

In two-way radio systems, talk groups are used to organize communication. Some situations may call for creating a temporary talk group, but there are no straightforward ways to do this. Making a new talk group requires programming radios off-line. Temporary groups can be created, but this requires inputting radio IDs which is tedious on a radio's limited controls. By describing group members using attributes, ciphertext-policy attribute-based encryption (CP-ABE) can be used to quickly create sub-groups of a talk group. This scheme requires fewer button presses and messages sent in the new talk group are kept secret. CP-ABE can be used on deployed hardware, but performance varies with the type of embedded processor and the number of attributes used. Because radio communication is time-critical, care must be taken not to introduce too much audio delay. By using benchmark programs on a variety of single-board computers, we explore the limits of using CP-ABE on a two-way radio.