Star type optical fiber grating sensing network based on CDMA multiplexing and demodulation method

Abstract

The invention discloses a demodulation method of a star fiber grating sensing network based on the code division multiple access multiplexing. The star fiber grating sensing network is provided with at least one broad band light source which is connected with the input ends of a plurality of coding / sensing grating units connected in parallel, the output ends of the coding / sensing units are connected with a self-correlation digital demodulator through a star coupler; and the centre wavelengths of the coding / sensing grating units are all in a flat region of the broad band light source power spectrum. The star fiber grating sensing network can be flexibly arranged, and can ensure that the autocorrelation digital demodulator obtains signals with enough signal-to-noise, thereby being favorable to telemetering, having easy maintenance, convenient expansion and high reliability, and being an optical fiber sensing network structure suitable for the engineering application.

Description

technical field [0001] The invention relates to a star fiber grating sensing network based on code division multiple access and a demodulation method thereof. Background technique [0002] As a new type of sensor device, the biggest feature of the fiber grating sensor is its strong multiplexing ability and low transmission loss. It is easy to form an optical fiber sensor network through various multiplexing technologies. There are broad application prospects in many fields. [0003] For a long time, the high cost of fiber grating sensors has been an important reason hindering its popularization in engineering applications. In response to this situation, people generally use multiplexing technology to solve it by reducing the average cost of a single fiber grating sensor. More common at present are wavelength division multiplexing technology, space division multiplexing technology, time division multiplexing technology and their combination. [0004] Wavelength division mu...

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Problems solved by technology

[0006] (1) The energy signal (optical signal emitted by the light source) and the measurement signal (optical signal returned by the optical fiber sensor) are bidirectionally transmitted along the same optical fiber, which cannot be amplified, so it is not conducive to long-distance measurement and is not conducive to improving system information. noise ratio;

[0007] (2) Fiber Bragg grating sensors are connected in series, and any sensor failure will make the whole system unable to work, so the reliability is low and the maintainability is poor;

[0008] (3) The system capacity is determined at the initial design, and it is difficult to change once it is completed, so the flexibility is poor, and it cannot meet the user's requirements for system expansion in subsequent use;

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