Experimental measurements of propagation characteristics for maritime radio links

International audienceThis paper presents studies, carried out by Télécom Bretagne, concerning new radio technologies (mainly WiMAX, 802.16e) in the maritime environment. The aim of these studies is to reinforce the quality and the robustness of such transmissions. Several measurements were set up to characterize the propagation channel in maritime environment in order to study the communication performances of WiMAX. This characterization was obtained by specific experimental devices, developed and implemented by Télécom Bretagne. The experimentations were carried out at frequencies of 3.5 GHz (Licensed WiMAX Band in France) and 5.8 GHz (Free Band in France). Similar studies [1] and [2] were already carried out, but they did not take into account all the environment characteristics, namely tides and coast relief masking. Our study looks at these parameters for a better understanding of the propagation in operational transmission environments. In this paper, measurements were carried out by measuring the mean received power both for several distances over the sea and for a coastal point-to-point link during long periods. Part of the work presented in this paper has been obtained during the Ex’treme projec

Activ immunization of the breeding common pheasant (Phasianus Colchicus) against the disease of the mottled spleen virus

Une expérience d'immunisation de faisandeaux contre le virus de la Maladie de la Rate Marbrée a été réalisée en laboratoire. L'antigène utilisé est le virus de l'Entérite Hémorragique du dindon, multiplié sur dindon neaux et administré per os. Les auteurs décrivent les protocoles de production de cet antigène, son contrôle, les résultats cliniques et séro- logiques obtenus sur les faisandeaux ainsi immunisés.An experiment was done concerning experimental immunisation of young pheasants against Marble Spleen Disease Virus. The antigen used was an Hémorragie Enteritis Virus of Turkey and it was produced on turkeys. Immunisation was done by putting this antigen by oral route. Authors are describing methods for producing this antigen, controles, and clinical and serological results obtained

A real time ionospheric channel evaluation and simulation system

International audienceHF propagation simulators have been used for many years to evaluate the performance of data modems. They allow testing to be carried out under repeatable, specified, propagation conditions and therefore allow performance comparisons to be made between different modems. Additionally, they allow simulation of a wide range of propagation conditions, whilst avoiding the expense of extended on-air trials. The bit error rates (BERs) for three modems have been generated with SUEDE (Simulation Using Extended Dispersion Envelope), a non-real-time HF channel simulation system, for a six hour simulation period. A comparison with existing Watterson (1970) model techniques for estimating modem availability has been presented, and a method of improving the Watterson model techniques has been suggested. Results from the new method show good agreement with the SUEDE simulation. The technique cannot provide estimates of BER in the same way as a full SUEDE simulation. However, this may not be required, especially for the serial tone modems, which break and recover very abruptly as the SNR difference changes sign

Experimental measurements of maritime radio transmission channels

International audienceThis paper focuses on experimental measurements, carried out by Télécom Bretagne, concerning both maritime radio transmission channels and new radio technologies (mainly WiMAX, 802.16e). The aim of these studies is to reinforce the quality and the robustness of such transmissions. Several measurements were set up, with specific experimental devices developed and implemented by Télécom Bretagne, to characterize of the propagation channel in maritime environment and to study the communication performances of WiMAX. The experimentations were carried out at frequencies around 3.5 GHz (Licensed WiMAX Band in France) and 5.8 GHz (Free Band in France). A previous paper published by the same authors showed that there is a good agreement between the theoretical values of field attenuation computed with the well known two-ray model and the measurements. New measurements presented in this present paper confirm the possible presence of deep fading and bring to light the benefit to exploit the channel diversity thanks to the use of two receiving antennas separated in height. Furthermore, a comparison between the propagation characteristics and the performances of a WiMAX transmission are analyzed in order to have a better comprehension of the functionality of the system. Some results concerning maritime HF and UHF transmission channels are also proposed in this paper