Remote communication interface for sound and vibration sensors

Abstract

In this paper are presented the results regarding the implementation of a communication interface dedicated for conditioning and remote transmission of measurement signals acquired from sound and vibration sensors. The interface contains two parts, an analog section, responsible with long distance signal transmission and a digital section that realize demodulation and analog-to-digital conversion of the received signal. The analog part of the interface uses the frequency modulation technique that is well known for its ability to operate in environments characterized by high levels of electrical perturbations, even when are realized high speed data transmissions. The acquisition of signals from sensors is realized with a resolution of 16 bits with a maximum speed of 200kS/s. In order to ensure the compatibility with various communication media and different types of sensors, the proposed circuit has adjustable carrier frequency in the range [0,01 – 0,5] MHz and offers also the possibility to select the carrier signal waveforms: square or sinusoidal wave. In addition, for increased versatility, the communication interface combines two alternative configurations, one based on phase-locked-loop (PLL) structure and the second based on quadrature oscillator with analogue multipliers. Both configurations were thoroughly tested for evaluating the performances of the proposed design. In comparison with other structures, the remote communication interface proposed in this work revealed good stability, accuracy and reliability. Also, the robustness and simplicity of the interface due to the use of frequency modulation technique represent other significant advantages.