Long-distance trunk line safety fiber wavelength division multiplexing type warning system

Abstract

A long-distance trunk line safety fiber wavelength division multiplexing type warning system is formed by a light path and a signal processing module which collects light path signals. The light path comprises two aplanatic interferometers and one Michelson interferometer. The above three interferometers use three different wavelengths to concentratedly transmit to one fiber so as to form an induction fiber through a wavelength division multiplexer. Three light sources emit three lasers with different wavelengths and the lasers are taken as the light signals. The above three interferometers feel a vibration signal and divides the vibration signal into three paths through the wavelength division multiplexer. The three paths of the signals are transmitted to a photodiode respectively. The signal processing module processes the vibration signal collected by the photodiode, determines an abnormal disturbance position and emits an alarm signal.

Description

technical field [0001] The invention discloses an optical fiber wavelength division multiplexing early warning system. Background technique [0002] The traditional long-distance trunk line safety optical fiber early warning system adopts the trunk line monitoring technology based on the principle of double Mach-Zehnder fiber optic interference. [0003] The principle structure of the technology is as follows figure 1 shown. The monitoring principle is that the two beams of light transmitted in the distributed sensing fiber propagate in opposite directions. After being affected by the same vibration event, the optical paths of the two beams of light from the place where the event occurs to the respective detection points are different. A certain time difference, according to the time difference of the interference light signal change caused by the same event monitored by both ends of the sensor, through the correlation analysis method, the position of the abnormal disturba...

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Problems solved by technology

[0004] This method does not need to demodulate the phase of the interference signal, but it also has disadvantages: because the two sensing fibers are close to each other, the vibration along the sensing fiber may make the phase delays of the two sensing fibers consistent, resulting in no Interference, resulting in reciprocity effect; long-distance temperature changes along the way will lead to large system noise, which will bring difficulties to signal processing; at least three cores in the optical cable need to be occupied, which is difficult to apply in the case of few optical fiber resources; High hardware requirements, such as high A / D conversion rate requirements for data acquisition systems, resulting in increased system costs

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