Sistema de telemetria bidirecional versátil.

Abstract

This paper presents the design and implementation of telemetry systems for short and medium ranges. Two configurations are focused: one unidirectional, where the remote unit sends data to the local unit, and another two-way, where there is information flow in both directions. In this last one, an analysis is made of the operational strategies of the link between the local and remote units and their applications. In both configurations, dual modulation is used, the first PWM (analogue and digital) and second ASK, with carrier in the 27 MHz band. Both configurations are multi-channel with time division multiplexing. The remote and local drives are based on the 68HC11 microcontroller, allowing greater versatility for the link. This microcontroller performs data acquisition, multiplexing and processing of signals, modulation of signals, to be transmitted, demodulation of received signals, as well as error detection. Different applications are possible by changing only the "software". The implemented bi-directional configuration provides for a local unit and four remote units, so that only one transmitter is active at a given time and this control is done by the 68HC11. Validation tests were performed with analogue and digital signals, obtaining satisfactory results.