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In this paper, we propose a methodology to use the received signal strength indicator (RSSI) available by the protocol stack of an installed Wireless Sensor Network (WSN) at an electric-power-system environment (EPS) as a tool for obtaining the characteristic of its communication channel. Thereby, it is possible to optimize the settings and configuration of the network after its deployment, which is usually run empirically without any previous knowledge of the channel. A study case of a hydroelectric power plant is presented, where measurements recorded over a two-month period were analyzed and treated to obtain the large-scale characteristics of the radiofrequency channel at 2.4 GHz. In addition, we showed that instantaneous RSSI data can also be used to detect specific issues in the network, such as repetitive patterns in the transmitted power level of the nodes, and information about its environment, such as the presence of external sources of electromagnetic interference. As a result, we demonstrate the practical use of the RSSI long-term data generated by the WSN for its own performance optimization and the detection of particular events in an EPS or any similar industrial environment.

An instrumentation amplifier with variable gain suitable for biopotential signal acquisition is presented. The architecture proposed is based on the superregenerative receiver created by Armstrong back in the 1920's. It allows controlling the gain by the duty-cycle of a digital clock. This feature reduces the complexity for implementing an automatic gain control circuit, since no digital-to-analog converter is needed in the interface of the gain control. The implemented instrumentation amplifier provides a variable gain of 40.2 dB with a 0.5 dB gain-step resolution, plus a fixed gain of 28.2 dB, giving a total gain range of 68.2 dB dB. It was evaluated by acquiring ECG signals using only two electrodes installed on the body of a volunteer. Results show that the amplifier acquires the ECG signal and that it is capable of adapting its gain to a specified voltage amplitude for delivering it to an A/D converter.

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