Protótipo de baixo custo de analisador RS-232 síncrono e protocolo HDLC para linhas de radiodeterminação

Abstract

This work aims to develop a prototype of a low-cost electronic device for evaluating RS-232 signals, in order to inspect indicators of flow control, synchronization and content from HDLC protocol frames in the data link layer. The proposed application seeks to stimulate the development of alternatives for inspection equipments of telecommunications links, through embedded systems at the national level. This proposal contributes to speeding up the inspection and maintenance of radiodetermination lines in the context of the Brazilian Airspace Control System, in order to provide less downtime of radar surveillance sensors. It would optimize the accuracy in projecting the position of evolving aircraft in the airspace, and, in turn, would contribute to a lower risk of aircraft incidents, which, when they occur, can cause financial losses and loss of human lives. First, the theoretical foundation is presented with a literature review, which conceptualizes the main telecommunications technologies used in the links involved, as well as theories and tools used in the design of embedded systems. Next, the steps and materials necessary for the construction of a printed circuit board responsible for equalizing the voltage levels used in RS-232 and TTL are presented, using discrete components that are easily acquired in the national market. Subsequently, an application for the detection and the removal of bits by software is demonstrated, as well as classification, grouping and sending of these received data to a mobile device through a bluetooth transceiver. For the work’s results, the tests and data collected in the validation of the prototype are presented in relation to the equalization of voltage levels and the operating range of the synchronism signals. Comparative data between those obtained by the locally available tools and the developed prototype are also presented. Finally, the data obtained are analyzed to validate the hypothesis about the possibility of developing a device that meets the requirements for inspecting signals from the data link layer on radiodetermination lines.