| The objective of this work is to analyze a communication system based on a telemetric connection between devices placed on the electrical supply network and a center of control. This system will be used for transmitting and receiving measures taken by a current measuring device.;This report presents a theoretical study of the telemetric technique by using Spread Spectrum. It is composed of two parts: the first consists in studying the transmission techniques of values read by the measuring device and the second deals with the reception of values transmitted by the transmitter.;Several techniques are used in the systems of spread spectrum like the technique of direct sequence, frequency hopping and chirp FM. In this report, the study is based on the method of direct sequence by using the binary phase shift keying.;The code synchronization can be the most significant problem in ES technology due to the sources of uncertainties such as the carrier-frequency ( Doppler frequency shift) and code-phase. This synchronization is regulated in two stages: an initial synchronization, and a tracking.;Data acquisition is based on a micro-controller, 68HC11 of Motorola and a data acquisition chip, LM12458 of National Semiconductor. To achieve this acquisition, the micro-controller program is explained in details. (Abstract shortened by UMI.). |
