Etude et réalisation d’une balise de transmission numérique Terre/Troposphère.

Abstract

The theme of our thesis is the study, design, and realization of the first 406 MHz Algerian beacon by the doctoral student Ali Srihen Billel digital transmission associated with a 406 Mhz mobile frame decoder. The atmosphere is a vector that is important for transmission and reception times. Climatic and geographical factors affect the quality of transmission and, at the same time, reception, as research evolutions progressed, led us to integrate the higher levels, and even the distant orbits. This study has been divided into two main parts, one theoretical and the other practical. It seems necessary to present the structure of the atmosphere with the different types of propagation, as well as the physical bases of the tropospheric propagation, to expose the effects of the tropospheric propagation to have an optimal radiation. A new type of photonic antenna is proposed, it is capable of sending complex (digital) signals, while guaranteeing the security of the information contained in the frames. The general structure of the COSPAS SARSAT system, its operating concept, the rules that govern the system, its role of rescue, the recovery of information from distressed targets, locations and organization of rescue. The practical part, relative to the design, the realization of the Beacon 406 MHz, as well as the mobile decoder receiver associated with our Beacon, the receiver is able to monitor all the different frequencies used by 406 MHz beacons. The achievements as well as the tests and results were carried out at the G2Elab Electrical Engineering Laboratory in Grenoble with success. The real-life operating tests were carried out with the assistance of the amateur radio station of Grenoble France, the only civilian authority authorized to transmit signals and receive them in the 406 MHz band, the registration of the beacon and the tests. Complementary projects were conducted under the direction of Professor Jean-Paul Yonnet, who supervises my internships. The emission and reception of a Beacon 406 MHz signal, requires to know the phenomenology of the troposphere, to ensure the best quality of the signal, to identify the interference, as well as the fading, which are likely to influence the show and the reception. For the sake of miniaturization of the beacon, we opted for a micro photonic antenna, in order to improve the reception of the signal of the beacon in distress, and a future encryption of the emitted signals, we demonstrated the balance of link for the MEOSAR system, we have shown that the uplink is more sensitive compared to the MEOLUT downlink, finally we have evaluated the impact of the signal rise time and the symbol rate on the demodulation performance of the distress message, each country participating in this system must comply with all the regulations developed by COSPAS SARSAT. As we pointed out above, our Beacon tested in actual deployment situation, the results obtained are promising, it is interesting to undertake deeper research, in order to have the best explanatory panorama of the operation of the beacon, for a multitude of functions, including coverage of land borders including a set of network encompassing beacons, cameras and sensors. In this way, the monitoring of large oil and gas installations can be envisaged with structured network tags including temperature, pressure and humidity sensors as well as a warning system.