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PDH multi-sensor strain measuring device using pseudo-random code division multiplexing

A code division multiplexing, pseudo-random code technology, applied in the field of PDH multi-sensor strain measurement devices, can solve the problems of continuous observation by a single sensor, limited frequency sweep accuracy, adjustable light source accuracy, and high cost, and achieve temperature stability. and good anti-vibration stability, improve demodulation accuracy, and save the effect of transformation cost

Active Publication Date: 2019-06-14
HARBIN ENG UNIV
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Problems solved by technology

Because the wavelength division multiplexing technology uses a wide-band frequency-sweeping light source, it is expensive, and the frequency-sweeping accuracy is limited by the adjustable accuracy of the light source
Time-division multiplexing technology cannot continuously observe a single sensor because of the interrogation operation.

Method used

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  • PDH multi-sensor strain measuring device using pseudo-random code division multiplexing

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Embodiment 1

[0029] The invention is an improvement to the optical fiber resonant cavity technology based on PDH technology. It solves the multiplexing and demodulation process in the multi-sensor cascading process of a single fiber, and realizes the simultaneous measurement scheme of multiple fiber gratings. The basic principle adopted is to use the spread spectrum property of random code modulation to realize the code space separation of signals. Among them, the working principle of PDH is as follows figure 2 As shown, taking the use of a fiber grating Fabry-Perot resonator for strain testing as an example, the laser light emitted by the narrow linewidth laser 501 is sent to the phase modulator 503 for phase modulation after passing through the optical isolator 502. The modulated signal of the phase modulator 503 is generated by the RF signal generator 508, and the modulated optical signal is sent to the optical fiber looper 504. Since light with different polarization states will gen...

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Abstract

The invention relates to a PDH multi-sensor strain measuring device using pseudo-random code division multiplexing, and belongs to the technical field of photoelectric detection. A high-stability light source and modulation module in the invention is connected with a single-mode optical fibre loop, a polarization state controller and an integrated multi-channel fibre grating resonator in sequence;and the other end of the single-mode optical fibre loop is connected with a random code modulation and demodulation module, a photoelectric detector, an orthogonal demodulation module, a data acquisition card, a PID controller and the high-stability light source and modulation module in sequence. According to the PDH multi-sensor strain measuring device using pseudo-random code division multiplexing in the invention, multiplexing of multiple fibre gratings can be realized; the device is easy to realize; furthermore, the improvement cost can be reduced; noise can be reduced through a code division multiplexing technology; furthermore, any fibre grating can be measured continuously for a long time; noise is eliminated; the signal demodulation precision is improved; an all-fibre optical pathis adopted; the device has the characteristics of being small in volume, high in measurement precision, good in temperature stability and anti-vibration stability and the like; a demodulation algorithm can be in digital hardware implementation; after being acquired, a signal also can be sent into a computer to demodulate; and the design is flexible.

Description

technical field [0001] The invention belongs to the technical field of photoelectric detection, in particular to a PDH multi-sensor strain measurement device using code division multiplexing of pseudo-random codes. Background technique [0002] Fiber Bragg Grating (FBG) sensors have been effectively applied in smart materials and structural monitoring due to their small size, high-speed response characteristics, and easy reuse. However, for high-precision temperature and strain observation, a single fiber grating cannot meet the requirements because the reflection peak is too wide. Therefore, fiber gratings can be used to form a resonant cavity to reduce the width of the reflection peak and obtain more accurate observation signals. Therefore, many improved FBG measurement schemes have been proposed, such as using phase-shifted FBG and FBG interferometer instead of ordinary FBG, and using laser frequency locking technology to improve the measurement accuracy of FBG. Among t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/16
Inventor 杨军张毅博田帅飞邹晨祝海波苑勇贵李寒阳苑立波
Owner HARBIN ENG UNIV
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