Digital signal processing technique for increased resolution of a gas detector

Shchuchkin E. Yu.

The study solves the problem of increasing resolution ability of gas detectors with the use of methods of digital signal processing of the signal from an analog gas sensor. The task is significant for industrial and domestic gas detectors. The article provides a diagram of the digital processing path for a typical gas detector module based on a microcontroller with an analog-to-digital converter, an operational amplifier and a gas sensor. The proposed signal-processing path includes temperature compensation unit and a digital low-pass filter. The paper proposes a quasi-linear model of the dependence of the gas sensor signal of temperature for generating of correction coefficients that can compensate the temperature error when operating in an extended temperature range. An algorithm proposed for the implementation of a digital low-frequency filter that increases the resolution of the gas detector based on interpolating the initial discrete data with cubic splines. An important mathematical result of the study is that the method of selecting interpolation nodes allows minimizing the absolute error modulus of the approximating curve with respect to the initial data. Based on the simulation results, a comparison made be-tween the filter described in the article and the median filter. From the point of view of the theoretical study, the proposed method of digital signal processing can increase the resolution of gas detectors in determining the gas concentration, allowing abandoning installation of precision components and reducing the cost of the final product.

Keywords:digital signal processing, analog sensor, gas detector, median filter, interpolation, sensor resolution.