Design of Non-dispersion Infrared Detector's Data Processor on Measurement of Automobile Emission CO and CO2

摘要

For the technical requirements of automobile emission CO and CO_2 detector's data processor, the scheme is based on the detection principle of NDIR method and the implementation of data processor' software as well as hardware is discussed. High-speed high-precision DSP is selected as the core of the detector's data acquisition and processing, while four-channel thermoelectricity sensor TPS4339 as infrared detector, digital-analog data acquisition circuit of NDIR is designed and simulated. Then fast Fourier transform (FFT) is adopted for signal processing. Automobile emission CO and CO_2 concentration can be accurately obtained by appropriately adjusting sampling period and the light source modulation frequencies, the system SNR is improved and the detection limit is reduced. The experimental results show that the detector's data processor has 3% accuracy and stability which can meet the measurement and analysis of automobile emission CO and CO_2 concentration.