An FPGA-based data acquisition system with embedded processing for real-time gas sensing applications

Real-time gas sensing based on wavelength modulation spectroscopy (WMS) has been widely adopted for several gas sensing applications. It is attractive for its accurate, non-invasive, and fast determination of critical gas parameters such as concentration, temperature, and pressure. To implement real-time gas sensing, data acquisition and processing must be implemented to accurately extract harmonics of interest from transmitted laser signals. In this work, we present an FPGA-based data acquisition architecture with embedded processing capable of achieving both real-time and accurate gas detection. By leveraging real-time processing on-chip, we minimised the data transfer bandwidth requirement, hence enabling better resolution of data transferred for high-level processing. The proposed architecture has a significantly lower bandwidth requirement compared to both the conventional offline processing architecture and the standard I-Q architecture. Specifically, it is capable of reducing data transfer overhead by 25% compared to the standard I-Q method, and it only requires a fraction of the bandwidth needed by the offline processing architecture. The feasibility of the proposed architecture is demonstrated on a commercial off-the-shelf SoC board, where measurement results show that the proposed architecture has better accuracy compared to the standard I-Q demodulation architecture for the same signal bandwidth. The proposed DAQ system has potential for more accurate and fast real-time gas sensing.