Infrared simultaneous gas detector for an atmospheric environmental network

摘要

Abstract: A pollutant gas detector is presented. The sensor system detects simultaneously CO and SO$-2$/ in a range from 0 to 200 ppm with a resolution of 7 ppm, however the system is bale to analyze up to 19 gases simultaneously. A new technique based on a multilayer filter array is proposed to prevent the use of moving parts. The central-wavelengths of filters were selected according to the position of the absorption band of interest for each gas. The CO and SO$-2$/ central-wavelengths were measured and its transmission spectral response was also predicted by using the HITRAN database. Also a new conditioning circuit with high- performance is proposed using low-cost components. The circuit is based on shifting the measured signal to intermediate frequency. With this technique a reduction of 1/f noise is achieved. The new systems features reduction of moving parts, high acquisition speed and low-cost. !15