Pseudo-differential wavelength modulation optical fiber methane gas concentration detection device and method

Abstract

The invention discloses a pseudo-differential wavelength modulation optical fiber methane gas concentration detection device and method. The device comprises a driving signal generator connected with a light source, wherein the light source is further connected with a temperature controller, a light signal output by the light is transmitted to a photoelectric detector to be converted into a current signal and then amplified and converted into a voltage signal by a weak signal amplifier, the voltage signal output by the weak signal amplifier enters a differentiator, the differentiator is used for performing frequency domain partial differential and frequency domain partial amplification on the voltage signal, an output of the differentiator is divided into two paths, the first path only intercepts a low-voltage signal of a square signal, the second path only intercepts a high-voltage signal of the square signal, the two paths of signals are respectively inputted into a low-pass filter to perform low-pass filtering treatment and then inputted into two input ends of a differential amplifier to be differentially amplified, an output signal of the differential amplifier is transmitted into a controller, and the controller takes integrals of the differentially amplified signals to obtain a methane gas concentration.

Description

technical field [0001] The invention belongs to the field of gas detection, and in particular relates to a pseudo-differential wavelength modulation optical fiber methane gas concentration detection device and method. Background technique [0002] Gas concentration detection methods include electrochemical, electrical, gas chromatography and optical methods. Electrochemical method uses electrochemical methods to detect gases using electrodes and electrolytes; electrical methods use semiconductor gas-sensitive devices for detection; gas chromatography is a physical separation and analysis technology, which uses adsorbents to make material components according to the strong adsorption capacity. Weak chromatography is a laboratory method in chromatography; optical methods use the optical refractive index or spectral absorption properties of gases to detect gases. [0003] The current method for detecting the methane gas concentration of optical fiber is an optical method based...

AI Technical Summary

Problems solved by technology

[0012] (1) There is a certain difference between the detection signal link and the reference signal link, and the random noise is also inconsistent, which will affect the detection accuracy

[0013] (2) For broadband light sources, the detection accuracy is low

In order to obtain high-precision measurement results, the harmonic detection method uses frequency multipliers, lock-in amplifiers, and integrators in the signal chain, and uses Fourier transform and division algorithms in the algorithm processing process. The analytical analysis algorithm and compensation deviation algorithm for the central wavelength of the absorption spectrum of quasi-methane gas are very difficult to implement technically

[0017] (2) Long response time

The algorithm processing of the harmonic detection method is too complicated. In order to obtain enough time-domain data, a long processing cycle is required, and the single response time of detection is sacrificed.

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