CN103954349A - Lateral positioning method for distributed optical fiber vibration sensing system - Google Patents

Abstract

Present invention discloses a kind of lateral register methods that can be used for Distributed optical fiber sensor system, step 1: the highest point of Oscillation Amplitude in search optical fiber, and the point is defined as first sensor points S1; Step 2: definition is second sensor points S2 at a distance of the point of d distance with first sensor points S1; Step 3: obtaining the time difference Δ t that vibration source vibration signal reaches first sensor points S1 and second sensor points S2; Step 4: calculating the lateral distance for obtaining vibration source apart from vibrating sensing optical fiber Wherein v is the spread speed of vibration signal in the soil. Localization method of the present invention can accurately measure lateral distance of the vibration source apart from optical fiber, and can realize merely with existing Distributed optical fiber sensor system.

Description

A kind of lateral register method of distributed optical fiber vibration sensing system

Technical field

The present invention relates to a kind of distributed optical fiber vibration sensing system lateral register method.

Background technology

Distributed optical fiber vibration sensor is because it is simple in structure, and detection range is long, is not subject to the features such as electromagnetic interference (EMI), has become the study hotspot of recent domestic.Distributed optical fiber vibration sensor part is the technology of the field active demands such as national defence, oil pipeline, electric power; this technology can be used for the invasion situation of Real-Time Monitoring boundary line, the pilferage of the destruction of oil pipeline and pilferage situation, power cable and destruction situation, realizes the protection to national wealth and life security.Distributed optical fiber vibration sensor is mainly based on two kinds of principles: a kind of is distributed optical fiber vibration sensor based on optical fiber white light interference principle; Another kind is the distributed optical fiber vibration sensor based on Rayleigh back scattering spectrum principle of interference.

The structure of distributed optical fiber vibration sensor as shown in Figure 1, laser instrument sends the continuous light signal that live width is 5kHz, centre wavelength is 1550nm, power is that through acousto-optic modulator (AOM), to be modulated into pulse width be that 10ns repetition frequency is the pulse signal of 1kHz to 10mW.. narrow pulse signal injects sensor fibre through isolator (Isolator) and circulator (Circulator) after being amplified by fiber amplifier (EDFA1), for after optical fiber generation to Rayleigh scattering light.Rear orientation light is detected device (Detector) and is transformed into electric signal after being amplified by fiber amplifier (EDFA1) after optical filter (Filter).Electric signal is through amplifying, after electrofiltration ripple and sampling, sends into computing machine and carries out data processing and obtain distributed oscillating curve data.

The light signal of the continuous narrow linewidth that fiber laser sends, is modulated into the pulsed light of certain width by acousto-optic modulator.Pulsed light after modulation injects sensor fibre after circulator, pulsed light interacts and produces back scattering spectrum with fiber optic materials in sensor fibre, back scattering spectrum produces self-interference rear to when transmission, back scattering spectrum after interfering is after circulator, and through optical filter, filtering is converted to electric signal by photodetector again.Electric signal by electrical filter filtering, converts digital signal at collected card after amplifier amplifies, and finally enters in data handling system data are processed and analyzed.Signal generator in system is for driving acousto-optic modulator to produce pulse signal, and the synchronizing signal of pulse is sent to capture card simultaneously.Above-mentioned cloth formula optical fibre vibration sensor only has longitudinal register function, there is no lateral register function, has limited to the practical application of distributed optical fiber vibration sensor.

Summary of the invention

Technical matters to be solved by this invention is to realize a kind of lateral register method that can be used for Distributed optical fiber sensor system.

To achieve these goals, the technical solution used in the present invention is:

The highest location point of Oscillation Amplitude in step 1, search whole piece optical fiber, and this point is defined as to first sensor points S1;

The point that step 2, definition and first sensor points S1 distance are d is second sensor points S2;

Step 3, by S1 point and S2 point vibrational waveform are analyzed, obtain the mistiming Δ t that vibration source vibration signal arrives first sensor points S1 and second sensor points S2;

Step 4: calculate and obtain vibration source apart from the lateral distance of vibrating sensing optical fiber wherein v is the velocity of propagation of vibration signal in soil.

The invention has the advantages that and can measure accurately vibration source apart from the lateral distance of optical fiber, and only utilize existing profile fiber sense vibration system just can realize.

Accompanying drawing explanation

Below the content of every width accompanying drawing expression in instructions of the present invention and the mark in figure are briefly described:

Fig. 1 is distributed optical fiber vibration sensing system structural drawing;

Fig. 2 is localization method process flow diagram;

Fig. 3 is positioning principle figure;

Fig. 4 is the mistiming schematic diagram between t1 and t2;

Mark in above-mentioned figure is: 1, processor; 2, capture card; 3, signal generator; 4, driver; 5, acousto-optic modulator; 6, laser instrument; 7, the first fiber amplifier; 8, isolator; 9, circulator; 10, electrical filter; 11, signal amplifier; 12, photodetector; 13, optical filter; 14, the second fiber amplifier; 15, sensor fibre.

Embodiment

Known referring to Fig. 2, the lateral register method of distributed optical fiber vibration sensing system is as follows:

Step 1: capture card 2 is gathered to the data of returning and rearrange into the vibration data of arranging by time shaft, the highest location point of Oscillation Amplitude in search optical fiber, and this point is defined as to first sensor points S1;

Step 2: definition is second sensor points S2 with the point that first sensor points S1 distance is d, is self-defining value apart from d, for example, may be defined as 5 meters;

Step 3: the point of Oscillation Amplitude maximum is the nearest point of distance vibration source on optical fiber, the line of this 2 point (referring to Fig. 3, S1 point and vibration source S point) will be perpendicular to sensor fibre.The mistiming Δ t that arrives this 2 point (S1 and S2) by vibration source vibration signal adds that the velocity of propagation of vibration in soil just can calculate vibration source apart from the side direction vertical range of optical fiber, and mistiming Δ t obtains principle as shown in Figure 4;

Step 4: calculate and obtain vibration source apart from the lateral distance of vibrating sensing optical fiber wherein v is the velocity of propagation of vibration signal in soil.

This external system, before carrying out for the first time step 4 calculating, need to be proofreaied and correct v value.

Calculation side to the principle of distance y as shown in Figure 3, is chosen 2 S1 (x1, y1) and S2 (x2, y1) as two sensing points of location from optical fiber.The vibration signal source position that S (x, y) is to be positioned, wherein S1 point is the point of Oscillation Amplitude maximum.By vibration signal S, arrive the mistiming of S1 and S2, and the velocity of propagation of vibration signal in soil just can calculate S apart from the lateral distance of optical fiber,

(V.t1) ²+d ²＝(V.t2) ²

V is the velocity of propagation of vibration signal in soil, convert:

d ²＝(v·Δt) ²+2·Δt·t1·V ²

? $y=\frac{d^2-{(v.\mathrm{\Δt})}^2}{2.v.\mathrm{\Δt}}.$

Claims (2)

1. a lateral register method for distributed optical fiber vibration sensing system, is characterized in that:

The highest location point of Oscillation Amplitude in step 1, search whole piece optical fiber, and this point is defined as to first sensor points S1;

The point that step 2, definition and first sensor points S1 distance are d is second sensor points S2;

Step 3, obtain the mistiming Δ t that vibration source vibration signal arrives first sensor points S1 and second sensor points S2;

Step 4: calculate and obtain vibration source apart from the lateral distance of vibrating sensing optical fiber wherein v is the velocity of propagation of vibration signal.

2. the lateral register method of distributed optical fiber vibration sensing system according to claim 1, is characterized in that: system, before carrying out step 4 calculating, need to be proofreaied and correct v value.