Method and system for detecting concentration of optical-fiber methane gas on basis of oblique-wave modulation

Abstract

The invention discloses a method and system for detecting the concentration of optical-fiber methane gas on the basis of oblique-wave modulation. The method comprises the following steps of: with oblique-wave modulation signals as driving current of a light source, respectively obtaining a relation of change of the wavelength and the intensity of light signals emitted from the light source with the modulation signals; according to the beer-lambert law, obtaining light-intensity signals after absorption of the methane gas; carrying out differential processing on the light-intensity signals, thus obtaining processed signals; judging a time point t1 when the wavelength of the light source starts entering a methane-gas absorption line and a time point t2 when the wavelength of the light source is completely equal to the central wavelength of the absorption line; carrying out integration in the range of t1 to t2 on the integrated signals; and obtaining the concentration of the methane gas. The method and system disclosed by the invention have the beneficial effects that the signal algorithm analysis only relates to wavelength modulation and differential demodulation, so that the complex algorithms such as Fourier transformation and harmonic analysis are avoided, the signal processing time is saved and the response speed of detection is improved.

Description

technical field [0001] The invention relates to the technical field of gas concentration detection, in particular to an optical fiber methane gas concentration detection method and system based on ramp wave modulation. Background technique [0002] Gas concentration detection methods include electrochemical methods, electrical methods, gas chromatography and optical methods. The electrochemical method uses electrochemical methods to detect gases using electrodes and electrolytes; the electrical method uses semiconductor gas sensitive devices for detection; gas chromatography is a physical separation analysis technology that uses adsorbents to make material components according to their adsorption capacity. Weak chromatography is a laboratory method in chromatography; optical method is to use the optical refractive index or spectral absorption characteristics of gas to detect gas. [0003] The optical fiber methane gas concentration detection method is an optical method base...

AI Technical Summary

Problems solved by technology

The method and system can not only solve the problem of detection error caused by random signals such as signal link coupling degree and environmental noise in the optical fiber methane gas concentration detection method that interferes with the light intensity, but also eliminate the impact of light source wavelength drift on detection. , further improving the detection accuracy

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