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The Simulation Of Modulation Coefficient Of Gas Detection System And Experiment Based On TDLAS

Posted on:2015-01-09Degree:MasterType:Thesis
Country:ChinaCandidate:J QiFull Text:PDF
GTID:2268330425493550Subject:Physical Electronics
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Tunable Diode Laser Absorption Spectroscopy technology is widely used in the industrial production and environmental pollution monitor which high spectral resolution, low detection limit, fast response and high sensitivity gradually become the development direction of trace gas detection. As in all areas of TDLAS gas detection technology demand increase gradually, Such as mathematical software Matlab is used to realize the simulation of TDLAS technology has become a new research field. Using the virtual platform for simulating gas parameters, And further analyze the effect of changes on the measurement of optical parameters will be better interpretation of each step of the TDLAS technology, so as to provide related experimental parameters setting of reference, a signal-to-noise ratio (SNR) can be used as a measure of TDLAS gas detection system characteristics, the method of the TDLAS technology more feasible in practical application process.The analog signal is absorbed directly from the Beer-Lambert law of absorption of departure and by the HITRAN database to obtain the required gas absorption line spectral information using Matlab programming for direct simulation of gas absorption signal. Different linear calculations results and the results from commercial spectra software Hitran were compared. The simulation model of spectroscopy gas detection system based on tunable diode laser was established by using Matlab simulation software. This simulation model includes two parts:theoretical simulation part and the modulation factor regulating part. The theoretical simulation part is mainly absorption spectra, modulated signal absorption spectrum and the harmonic extraction diagram; the modulation factor part is modulating all the coefficients of the ideal model. The recent ranges of parameters were acquired by analyzing the variation. By comparing the simulation results with the default values to verify the consistency of the simulation results. Wavelength modulation spectroscopy simulation work first from the basic principle of TDLAS technology.The direct absorption signal modulation and demodulation of the simulation were achieved by using Matlab programming. The different line of the second harmonic signal with changing conditions of temperature and pressure were discussed. Finally, verification of the second harmonic amplitude versus modulation factor changes was achieved based on theory and experiments.
Keywords/Search Tags:gas detection, Tunable Diode Laser Absorption Spectroscopy, Absorption spectrum, modulation parameter, analogue simulation
PDF Full Text Request
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