A Portable Data Acquisition System for Online Wavelength Modulation Spectroscopy

Temperature and gas concentration are crucial parameters to be monitored in the combustion processes. As a non-intrusive laser measurement method, Wavelength Modulation Spectroscopy (WMS) has the advantages of high sensitivity, noise resistance, and fast response. To be cost-effective and flexible, it is highly demanded for an integrated, portable, and robust Data Acquisition (DAQ) system that runs without a high-level CPU. This paper aims to design a portable DAQ system using WMS for monitoring the gas parameters. The developed system consists of two main components with Ethernet communication between them: a Field Programmable Gate Arrays (FPGA)-based DAQ hub that digitizes, decomposes, and down-samples the measurement signal, and a Raspberry Pi that stores the data and enables online gas parameters monitoring using a data-driven neural network. The system is validated through a lab-scale combustion experiment, indicating its accuracy and efficiency.