Common-mode noise inhibition method and system in heterodyne demodulation fiber sensing system

An optical fiber sensing system and demodulation system technology, applied in the field of common mode noise suppression, can solve the problems of slowness, unstable system noise floor, poor suppression effect, etc.

Active Publication Date: 2018-08-24
PEKING UNIV
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  • Abstract
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  • Claims
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Problems solved by technology

However, relevant studies have shown [2] that the suppression effect of common mode noise is related to the DC phase of the normal sensor and the reference sensor
Suppression is best when the DC phases of both are equal, but worst when the DC phases differ by π / 2 or 3π / 2
However, in actual use, due to the slow changes in environmental temperature, stress and other factors, the DC phase of the normal sensor and the reference sensor will drift slowly and inconsistently, resulting in the instability of the system noise floor obtained by the common mode noise suppression method [2]

Method used

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  • Common-mode noise inhibition method and system in heterodyne demodulation fiber sensing system
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  • Common-mode noise inhibition method and system in heterodyne demodulation fiber sensing system

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Embodiment Construction

[0063] The present invention will be further elaborated below through specific embodiments in conjunction with the accompanying drawings.

[0064] Such as figure 1 As shown, the suppression system of the common mode noise of the heterodyne demodulation optical fiber sensing system of the present embodiment includes: a pulse generating device, a circulator, a sensor array, a reference sensor, a detector and a demodulation system; wherein, the pulse generating device is connected to The first port of the circulator; the second port of the circulator is connected to the sensor array; the sensor array is connected to the reference sensor in series; the third port of the circulator is connected to the detector; the detector is connected to the demodulation system. The circulator has the following optical properties: an optical signal can be transmitted from the first port to the second port, and from the second port to the third port, and vice versa.

[0065] Such as figure 2 As...

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Abstract

The invention discloses a common-mode noise inhibition method and system in a heterodyne demodulation fiber sensing system. A reference sensor based on a heterodyne scheme is formed by a 3*2 coupler,three paths of reference signals are combined linearly, a DC multiplicative noise portion is eliminated, the characteristic that a 2pi/3 inherent phase difference exists among the three paths of reference signals of the 3*2 coupler is used, a DC phase value of a sensing interference signal equals a DC phase value of a reference interference signal via linear combination, and thus, an ideal common-mode noise inhibition effect is realized.

Description

technical field [0001] The invention relates to optical fiber sensing technology, in particular to a method and system for suppressing common mode noise in a heterodyne demodulation optical fiber sensing system. Background technique [0002] The optical fiber sensing system based on heterodyne demodulation is widely used in the fields of underwater acoustic detection, perimeter security and resource exploration because of its high sensitivity, strong anti-electromagnetic interference ability and excellent multiplexing ability [1]. . In these applications, the noise performance and dynamic range of the system are important indicators that need to be investigated. The core of this is the noise floor of the system, which determines the lower limit of the dynamic range of the system, and at the same time determines the minimum that the system can detect. signal amplitude. In fiber optic sensing systems based on heterodyne demodulation, the noise performance of the system is la...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D5/353
CPCG01D5/35306
Inventor 刘飞张敏何向阁易多古利娟
Owner PEKING UNIV
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