An automobile emission diagnosis system based on spectral absorption is introduced.Different gases have their corresponding absorption wave crest

so whose emission bandwidth is between the infrared and UV spectrum is selected as the light source

and the corresponding photo-detector constitutes photoelectric sensor.Applied to 16 bits A/D data acquisition module

ARM7 as the CPU

GPRS module communicates with the remote monitoring center PC which uses the virtual instrument technology can display the real-time data.Experiment result shows that it has high sensitivity

good repetition and powerful in real-time

the precision of detecting reaches 0.01 mg/s

which is an ideal equipment for detecting automobile emission.