Sensing system based on optical OFDM (Orthogonal Frequency Division Multiplexing) and FBG (Fiber Bragg Grating) monitoring method thereof

Abstract

The invention discloses a sensing system based on optical OFDM (Orthogonal Frequency Division Multiplexing) and an FBG (Fiber Bragg Grating) monitoring method thereof, relating to the field of optical fiber sensing. The sensing system comprises an adjustable optical source, an electrooptical modulator, an optical circulator, a weak reflective FBG array, a wavelength tuning control circuit, a signal generator, an optical detector and a digital decoding and control unit, wherein the adjustable optical source is used as a signal optical source; the electrooptical modulator is used for modulating data onto signal optical waves; the optical circulator is used for separating optical signals which are in an incident direction from optical signals which are in a reflective direction; the weak reflective FBG array is used as a sensing element for reflecting the optical signals to the optical circulator; the wavelength tuning control circuit is used for tuning the emitting wavelength of the adjustable optical source; the signal generator is used for generating electric signals which are encoded based on OFDM; the optical detector is used for converting the reflective optical signals into the electric signals; and the digital decoding and control unit is used for positioning an FBG sensor and acquiring variables to be detected. In the invention, by combining the FBG monitoring method based on the optical OFDM, the arrangement density and the sensing distance of FBG sensors are improved, the scanning frequency and the spatial revolution of the system are improved, and large-capacity measurement requirements are satisfied.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to an optical OFDM-based sensing system and a fiber grating monitoring method thereof. Background technique [0002] Optical fiber sensing technology is a sensing technology that uses optical fiber as the medium and light waves as the carrier to sense and transmit external measured signals. The optical fiber itself has a series of unique advantages that are difficult to compare with other media. Since the optical fiber itself is a large-scale passive sensor network with both sensing and information transmission functions, it can monitor the environmental parameters distributed along the optical fiber over the entire length of the optical fiber. Continuous measurement is performed, and the measured spatial distribution status and time-varying information are obtained at the same time, so it is especially suitable for large-scale and long-distance networking measurements. At pres...

AI Technical Summary

Problems solved by technology

However, this implementation has the following disadvantages: due to the total reflection at the FBG in series, the forward transmission loss is large, the sensing distance and the number of FBG sensors placed are limited; at the same time, the tuning performance of the wavelength-tunable laser limits the scanning frequency, so it is difficult to Suitable for the measurement of dynamically changing physical quantities

This TDM-based addressing method has the problem of spatial resolution: a wider optical pulse is required to increase the measurement capacity and increase the transmission distance, but the too wide optical pulse results in a lower spatial resolution of the measurement

At present, the minimum spatial resolution of the TDM system can only reach 2m, and the deployment density of FBG sensors is still limited, and the practical effect is still not ideal

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