Optimisation d'une liaison faisceaux hertziens numériques

Mémoire (de fin d'études) de l¿année 2006 dans le domaine Ingénierie - Technique de Communication et Télécommunication, note: 1,3, Hochschule Mannheim (Softwaretechnik und Datenkommunikation), langue: français, résumé: This report contains the development of a DVB-T link, using OFDM modulation in order to increase the resistance against fading. It starts with an extract of the recommendations of the International Telecommunication Union (ITU) about microwave links. In particular, we developed a detailed radio link budget taking into account the effects of fading. A channel model was created modelling an overland path. The report shows in detail the practical development in laboratory consisting in assembling the link model using the OFDM modulation. This work includes a test of the model with the channel model found. Furthermore, a diversity technique increases even more the efficiency, by transmitting the signal through two different frequency channels: the receiver chooses the less affected channel by switching between them. An MPEG transport stream switcher does this. Its development is also explained in the report. Finally, the installation of an experimental link in a fading polluted region and the analysis of the first results are being showed.