Aiming at the problems that the traditional non-dispersive infrared(NDIR)method for detecting carbon monoxide(CO)concentration is easily influenced by background gas

the noise interference is large and the precision is low

a NDIR method for detecting CO concentration based on gas filtering correlation(GFC)technology is proposed.On this basis

online CO concentration monitoring system is developed

and a long optical path White cell gas chamber with multiple returns of optical paths is designed.A signal detection software and hardware system based on Cortex—M4 core microcontroller and FreeRTOS real-time operating system is developed

which rea

lizes the online monitoring of trace-level CO gas concentration.The experimental results show that in the volume fraction range of 0~50×10

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the measurement precision reaches ±0.366%FS

the 24h zero point and range drift do not exceed 0.8×10

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and the detection limit reaches 0.106×10

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.The monitoring system has high precision

strong stability and low detection limit

which can provide reliable data support for environmental monitoring.