CN101255951B - Method for improving oil gas pipe leakage and performance of instruction testing distributed optical fibre sensor - Google Patents

Abstract

The invention relates to a method for improving the performance of a distributed optical fiber sensor for oil and gas pipeline leakage and intrusion detection using Golay codes. The detection signals in the sensing optical fiber are continuous optical pulse sequences modulated by Golay codes and their inverse codes. These optical pulse sequences It is a sampling signal for sensing optical fiber transmission loss. Reducing the pulse width in the optical pulse sequence can not only increase the sampling frequency of sensing optical fiber transmission loss, but also analyze the sensing optical fiber caused by pipeline leakage and third-party intrusion events in a larger spectral range. Adding the characteristics of transmission loss can also improve the spatial resolution of the synthesized backscattered light signal and improve the positioning accuracy of the new loss. On the other hand, increasing the number of optical pulses in the sequence can increase the number of sampling points for transmission loss. It helps to analyze the characteristics of the newly added transmission loss signal in the sensing fiber, and can also improve the intensity and signal-to-noise ratio of the synthesized backscattered light signal, and increase the distance of the detection pipeline.

Description

A method to improve the performance of distributed fiber optic sensors for oil and gas pipeline leak and intrusion detection

technical field

The invention belongs to the technical field of signal detection and analysis, relates to an online detection method, in particular to a method for improving the performance of a distributed optical fiber sensor for detecting oil and gas pipeline leakage and third-party intrusion events by using Golay codes.

Background technique

Pipeline transportation is an economical and convenient mode of transportation, which has unique advantages in the transportation of oil and natural gas, especially in terms of safety, convenience and efficiency. Long-distance oil and gas pipelines have become an important part of my country's energy artery, and their strategic position is very important. Long-distance oil and gas pipelines are characterized by multiple points and long lines, and most of them are buried pipelines. Due to the harsh service environment, corrosion, topographical settlement, heavy pressure, mechanical construction and man-made damage may cause damage to the pipeline and even leakage as the service time increases. Leakage will not only cause huge property losses and serious environmental pollution, but may even cause fires and explosions, threatening the safety of people's lives and property. It is very important to quickly judge and accurately locate third-party intrusion events such as pipeline leakage and heavy pressure that may cause external damage to pipelines, terrain settlement, mechanical construction, and man-made sabotage, and to detect leakage in time and predict hidden dangers of leakage.

At present, there are many methods for pipeline leak detection, which are divided into direct leak detection method and indirect leak detection method. The direct leak detection method is to use the detector to directly detect the leakage outside the pipeline to judge the leakage, including the leak detection cable method, the conductive high polymer leak detection method, the sensor optical cable method, the infrared method and the ground penetrating radar method, etc. The indirect leak detection method is to estimate the leakage by monitoring the operating parameters of the pipeline (such as pressure, flow, temperature, etc.), including the mass balance method, negative pressure wave method, pressure gradient method, crawling machine method in the pipe, statistical leak detection method, and stress wave method. , acoustic methods and real-time model methods. Among them, the sensing optical cable method is a detection method based on distributed optical fiber sensors, which has become a hot spot in the research of oil and gas pipeline safety detection technology.

Distributed optical fiber sensor is a new type of sensor that uses light as the carrier and optical fiber as the medium to sense and transmit external signals, which has developed rapidly with the development of optical fiber communication technology. The ability of the measurand to distribute information. A sensing optical cable is laid along an oil and gas pipeline. Pipeline leakage and third-party intrusion events that may cause external force damage to the pipeline will exert force on the sensing optical cable laid near the pipeline. The sensing optical fiber in the optical sensing cable produces transmission loss; in addition, the sensing optical cable can use natural rubber and other coating materials with swelling properties. When the oil pipeline leaks or leaks (drip), the coating material of the sensing optical cable will The volume of the oil expands, and the force generated by the expansion acts on the sensing fiber, causing the sensing fiber to bend and cause loss. External events that cause loss can be located using an OTDR. The system structure of a distributed optical fiber sensor based on OTDR oil and gas pipeline leakage and intrusion detection is shown in Figure 1.

As shown in Figure 1, the optical pulse generated by the laser pulse generator [101] is injected into the sensing fiber [2] from one end (called the input end) through the isolator [102] and the coupler [103] Propagate forward in [2], output at the other end (referred to as the output end) of the sensing fiber [2] and couple to the optical power detector [401] to convert it into an electrical signal, and then through amplification/filter [402], After analog/digital conversion and digital signal processor [403] unit processing, the result is sent to the computer data analysis system [5], which is called the output optical power detection module [4]. At the same time, during the forward propagation of the light pulse along the sensing fiber [2], backscattered light is continuously generated due to Rayleigh scattering and Fresnel reflection. The backscattered light travels backward along the sensing fiber [2] and returns to the input end, passes through the coupler [103] to the optical power detector [301], converts it into an electrical signal, and then passes through the amplification/filter [302], After analog/digital conversion and digital signal processor [303] unit processing, the result is also sent to the computer data analysis system [5], which is called backscattered light detection module [3]. The computer [5] analyzes and fuses the output data of the optical fiber output optical power detection module [4], obtains the changes of pressure and vibration signals along the path of the sensing optical fiber [2], and judges whether there is pipeline leakage or intrusion according to its spectrum characteristics The event occurs and is localized using the backscattered light detection module [3]. Therefore, the output optical power detection module [4] can obtain the spectral characteristics of the loss change on the sensing fiber [2] to determine the type of fault; the backscattered light detection module [3] is used to sense the static And dynamic loss measurement to realize fault location.

In the distributed optical fiber sensor system, the light pulse generated by the laser pulse generator [101] has two functions: one is that the backscattered light is continuously generated during the forward propagation of the light pulse in the sensing fiber [2]. At the input end, the spatial distribution of the newly added loss on the sensing fiber [2] is obtained by measuring the backscattered light; the second is the pipeline leakage and third-party The external interference generated by the intrusion event causes the loss of the optical pulse transmitted in the sensing fiber [2], and the output optical power changes, so the pulsed light can be used as a sampling pulse of the transmission loss of the sensing fiber [2].

The advantages of distributed optical fiber sensors based on OTDR oil and gas pipeline leakage and intrusion detection are: first, the pulse light source [101] and the backscattered light signal detection module [3] are at the same end of the sensing fiber [2], which can realize single-ended Fault location, when the sensing optical cable is broken due to events such as explosions and excavations, the fault event can still be located; the second is that the time for the backscattered light generated by the optical pulse at different positions on the sensing fiber [2] to return to the input end is different , will not interfere with each other, so multiple fault points can be located at the same time. The disadvantage is that the backscattered light signal generated when the light pulse propagates in the sensing fiber [2] is very weak, which is much lower than the energy of the light pulse, which directly affects the signal-to-noise ratio of the backscattered light and limits the detection distance. There is also a certain limit on the minimum interval between pulsed lights with sampling function.

In order to improve the signal-to-noise ratio of backscattered light, it is necessary to increase the energy of the light pulse. One way is to increase the power of the laser pulse generator [101], and the other way is to increase the temporal width of the light pulse. Once the peak power of the optical pulse has reached its maximum value and the sensitivity of the receiver is at its best, the signal-to-noise ratio of backscattered light can only be improved by increasing the optical pulse width. However, increasing the pulse width causes a decrease in the spatial resolution of the backscattered light signal. Therefore, there is a contradiction between the signal-to-noise ratio of backscattered light and the spatial resolution of the loss. The narrower the optical pulse, the higher the spatial resolution of the loss location, but the worse the signal-to-noise ratio of the backscattered light signal.

Another method to improve the signal-to-noise ratio of backscattered light is to transmit multiple pulses at a certain time interval, collect the backscattered light signal of each pulse separately, and then calculate the average value. There is a limitation here, that is, the next pulse can only be sent after all the backscattered light of the previous light pulse returns to the input end, otherwise the backscattered light of the previous pulse at a far position is closer to the next pulse The backscattered light superimposes on each other and interferes with each other. The minimum interval T between light pulses input into the sensing fiber [2] can be obtained by formula (1):

$\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, Z is the length of the optical fiber [2]; c is the propagation speed of the optical signal in vacuum; n ₁ is the refractive index of the fiber core; the constant 2 indicates that the optical pulse propagates to the output end of the sensing optical fiber [2] and the output generated at the output end The time it takes for backscattered light to return to the input (i.e., to and fro). Therefore, the longer the sensing fiber [2], the larger the time interval T between pulses and the smaller the frequency of pulse repetition.

As a light pulse propagates in a sensing fiber [2], the loss is modulated by perturbations generated by external events. The light pulse repeated with time T propagating in the sensing fiber [2] is also the sampling pulse of the transmission loss of the sensing fiber [2]. The longer the sensing fiber [2], the larger the time interval T between pulses, and the smaller the frequency of sampling pulses. According to the sampling theorem, the sampling frequency is at least twice the frequency of the maximum loss on the sensing fiber [2]. Therefore, the maximum frequency at which external events cause transmission loss in the sensing fiber [2] limits the minimum sampling frequency of transmission loss and the maximum time interval T of sampling pulses, thus limiting the distributed optical fiber based OTDR oil and gas pipeline leak and intrusion detection The detection distance of the sensor.

Contents of the invention

Aiming at the deficiencies in the above-mentioned prior art, the object of the present invention is to propose a method for using Golay codes to overcome the above limitations and improve the performance of distributed optical fiber sensors for leak and intrusion detection of oil and gas pipelines.

In order to achieve the above object, the technical scheme adopted in the present invention is:

At the input end of the sensing fiber, the output of the laser pulse generator is a sequence of light pulses whose amplitude is modulated by Golay codes and their inverse codes. The train of optical pulses propagating forward along the sensing fiber is modulated by perturbations generated by pipeline leaks and intrusion events. At the output end of the sensing optical fiber, the output optical power detection module collects the optical pulse sequence output by the sensing optical fiber and sends it to the computer for processing; the computer performs amplitude conversion on the pulse sequence signal output by the output optical power detection module to eliminate the Golay code and The modulation of their inverse code makes the amplitude of the output pulse sequence signal after transformation only related to the disturbance generated by pipeline leakage and intrusion events. On the other hand, the backscattered light generated during the forward propagation of the optical pulse sequence along the sensing fiber propagates back to the input end along the sensing fiber, and after being collected and processed by the backscattered light detection module, it is sent to the computer for processing. The computer synthesizes new backscattered light signals by using Golay codes and the backscattered light signals produced by the optical pulse trains modulated by their inverse codes along the sensing fiber. Compared with the single-pulse backscattered light signal, the signal of the synthesized backscattered light signal is stronger, and the spatial resolution of the two is the same, so that the distributed fiber optic sensor for pipeline leak and intrusion detection has the same accuracy in event localization Under certain conditions, the signal-to-noise ratio of the backscattered light signal can be improved by increasing the length of the optical pulse sequence, thereby increasing the monitoring length of the pipeline.

A method for improving the performance of a distributed optical fiber sensor for leak and intrusion detection of oil and gas pipelines using Golay codes, specifically comprising the following steps:

1) Near the oil and gas pipeline, an optical cable is laid in parallel with the oil and gas pipeline, and the sensing optical fiber is used as a sensor to monitor oil and gas pipeline leakage and third-party intrusion events in real time;

2) At both ends of the sensing fiber, a backscattered light detection module and a fiber output optical power detection module are respectively arranged;

The computer uses Golay codes and their inverse codes to modulate the laser pulse generator, so that the output of the laser pulse generator is a continuous optical pulse sequence whose amplitude is modulated by the Golay code and their inverse codes;

The optical pulse sequence output by the laser pulse generator is coupled into the sensing fiber through the isolator and the coupler and propagates forward in the sensing fiber; at the output end of the sensing fiber, the output optical power detection module collects the output of the sensing fiber The optical pulse sequence is sent to the computer for processing; the computer performs amplitude conversion on the pulse sequence signal output by the output optical power detection module, and eliminates the modulation of the Golay code and their inverse code; the computer analyzes the transformed optical fiber output optical power signal, Complete the measurement of the dynamic change of the full-diameter total loss of the sensing fiber and the determination of the fault type;

At the input end of the sensing fiber, the backscattered light detection module separately collects the backscattered light signal generated by the Golay code and their inverse code modulated light pulse sequence along the forward propagation of the sensing fiber, and sends it to the computer for processing; The above backscattered light signal is used to synthesize a new backscattered light signal. The spatial resolution of the synthesized backscattered light signal is the same as the backscattered light signal of a single light pulse in the sequence. In terms of signal strength, it is higher than that of a single The intensity of the pulse is proportional to the number of light pulses in the sequence; the computer completes the measurement and positioning of the static and dynamic loss of each point on the sensing fiber through the analysis of the newly synthesized backscattered light signal;

3) The computer obtains the characteristics of the pressure and vibration signals around the oil and gas pipeline through the analysis and fusion of the loss data on the sensing optical fiber, and judges and locates the occurrence of oil and gas pipeline leakage and third-party intrusion events.

Some other characteristics of the present invention are:

The laser pulse generator is either a laser diode or a laser triode, and the width and energy of the output light pulse are controllable.

The output of the laser pulse generator is a continuous light pulse sequence, the width of the pulses in the sequence is the same, and the amplitude is modulated by Golay codes and their inverse codes.

The lengths of the Golay codes and their inverse codes are both powers of 2.

The Golay codes and their inverse code-modulated light pulse sequences are input into the sensing fiber at a certain time interval, and the minimum interval is equal to the back-to-back angle generated by the last bit of light pulse in the sequence at the output end of the sensing fiber. The difference between the time when the scattered light returns to the input end of the sensing fiber and the time when the first light pulse in the sequence enters the sensing fiber.

The length of the optical pulse sequence propagating in the sensing fiber is the same as the length of the Golay code and their inverse code, which is also a power of 2.

The Golay codes and their inverse codes are pseudo-random signals, so at the output end of the sensing fiber, no filter is used, but the modulation of the Golay codes or their inverse codes is eliminated by transformation.

The sensing optical fiber in the sensing optical cable is either a single-mode optical fiber or a multi-mode optical fiber, and its transmission loss is sensitive to deformation, pressure and vibration signals.

The backscattered light detection module includes optical power detector, amplification and low-pass filter, analog/digital conversion and digital signal processor unit.

The output optical power detection module includes optical power detector, amplification and low-pass filter, analog/digital conversion and digital signal processor unit.

The backscattered light detection module and the output light power detection module can be integrated into one system, or can be separated and connected through a data communication network.

The backscattered light detection module and the output optical power detection module can work simultaneously or independently. The backscattered light detection module mainly completes the measurement and positioning of the static and dynamic loss of each point on the sensing fiber; the output optical power detection module mainly completes the measurement of the dynamic change of the total loss on the sensing fiber and the judgment of the fault type.

Described backscattered light detection module can be an OTDR, utilizes the communication interface (such as GPIB, RS-232) that OTDR provides or the network interface that OTDR provides to communicate with computer; It can also be that OTDR card is directly installed in the computer. The working state of OTDR is controlled by computer.

The method for improving the performance of a distributed optical fiber sensor for oil and gas pipeline leakage and intrusion detection according to the present invention has the following advantages:

1) In the method of the present invention, the detection signal of the sensing optical fiber is a continuous optical pulse sequence modulated by Golay codes and their inverse codes, and these optical pulse sequences are sampling signals of the sensing optical fiber transmission loss. Since the period (width) of the light pulse in the sequence is not limited, it can theoretically take any small value, so the width of the light pulse in the sequence can be reduced. On the one hand, by reducing the width of the light pulse in the sequence, the sampling frequency of sensing fiber loss can be increased, so that the computer can analyze pipeline leakage and third-party intrusion events that may cause pipeline damage in a wider spectrum range on the sensing fiber On the other hand, the computer-synthesized backscattered light signal has the same spatial resolution as the backscattered light signal of a single light pulse in the sequence, so by reducing the pulse width in the light pulse train, it is also The spatial resolution of the synthesized backscattered light signal can be improved at the same time, thereby improving the positioning accuracy of the added loss on the sensing optical fiber.

2) In the method of the present invention, the detection signal of the sensing fiber is a continuous optical pulse sequence modulated by Golay codes and their inverse codes. On the one hand, by increasing the number of pulses in the sequence, the number of sampling points for sensing fiber loss can be increased, which helps to analyze the characteristics of the new transmission loss signal in the sensing fiber caused by pipeline leakage and third-party intrusion events; on the other hand , since the signal strength of the synthesized backscattered light signal is proportional to the number of light pulses in the sequence, by increasing the number of pulses in the sequence, the signal-to-noise ratio of the synthesized backscattered light signal can be improved, thereby increasing the distributed optical fiber The sensor detects the distance of the pipeline.

Therefore, the method of the present invention can not only increase the distance of the distributed optical fiber sensor detection pipeline by enhancing the intensity of the backscattered light signal and improve the signal-to-noise ratio; Scope Analyze the characteristics of the loss on the sensing fiber caused by pipeline leakage and third-party intrusion events that may cause pipeline damage, thereby improving the overall performance of distributed fiber optic sensors based on OTDR oil and gas pipeline leakage and intrusion detection.

Description of drawings

Fig. 1 is a system structural block diagram of a distributed optical fiber sensor according to an embodiment of the present invention.

Fig. 2 is a group of waveforms of 64-bit Golay codes A and B of the embodiment of the present invention.

Fig. 3 is the autocorrelation function of 64-bit Golay codes A and B and the waveform of their autocorrelation function sum according to the embodiment of the present invention.

和

调制的激光脉冲发生器[101]输出的光脉冲序列信号的波形。Fig. 4 is 64 Golay codes A and B of the embodiment of the present invention and their inverse code

and

The waveform of the optical pulse train signal output by the modulated laser pulse generator [101].

Fig. 5 is the waveform before and after amplitude conversion of the optical pulse sequence signal output by the sensing fiber [2] according to the embodiment of the present invention.

和

调制的光脉冲序列的背向散射光信号合成新的背向散射光信号的过程。Fig. 6 utilizes Golay code A and B and their inverse code in the embodiment of the present invention

and

The process of synthesizing the backscattered light signal of the modulated light pulse sequence into a new backscattered light signal.

Detailed ways

As shown in FIG. 1 , the distributed optical fiber sensor of the present invention includes a sensing optical fiber and a backscattered light detection module and a fiber output optical power detection module respectively located at both ends of the sensing optical fiber. The method that utilizes Golay code that the present invention proposes to improve the distributed optical fiber sensor performance of pipeline leakage and intrusion event detection comprises the following steps:

1) The computer 5 uses Golay codes and their inverse codes to modulate the laser pulse generator 101, so that the output of the laser pulse generator 101 is an optical pulse sequence whose amplitude is modulated by the Golay codes and their inverse codes.

2) The optical pulse sequence output by the laser pulse generator 101 is coupled into the sensing optical fiber 2; during the forward propagation of the optical pulse sequence along the sensing optical fiber 2, its amplitude is modulated by the disturbance generated by pipeline leakage and intrusion events; At the output end of the sensing fiber 2, the optical pulse sequence signal is collected by the optical fiber output optical power detection module 4 and sent to the computer 5 for processing; the computer 5 first performs amplitude conversion on the optical pulse sequence signal to eliminate the modulation of the Golay code and their inverse code , the change of the output signal amplitude after transformation is only related to the interference of external events on the sensing fiber 2; then the computer 5 obtains the newly added transmission loss when the sensing fiber 2 is disturbed by pipeline leakage and third-party intrusion events through spectrum analysis Characteristics of signal changes.

Since the sampling signal of the transmission loss in the sensing fiber 2 is a continuous light pulse sequence, the period (width) of the light pulse in the sequence is not limited, and can take any small value in theory, so it can be achieved by reducing the period (width) of the light pulse in the sequence Width, increase the sampling frequency of the loss of the sensing fiber 2, so that the computer 5 can analyze the characteristics of the loss on the sensing fiber 2 caused by pipeline leakage and third-party intrusion events that may cause pipeline damage in a larger spectrum range.

3) At the input end of the sensing fiber 2, the backscattered light signals generated during the forward propagation of Golay codes and their inverse code modulated light pulse sequences along the sensing fiber 2 are collected respectively, and a new backscattered light signal is synthesized .

Backscattered light is continuously generated during the forward propagation of the light pulse sequence along the sensing fiber 2 . The backscattered light propagates back along the optical fiber 2 to the input end of the sensing optical fiber 2 . The computer 5 modulates the amplitude of the light pulse signal output by the laser pulse generator 101 with the Golay code and their inverse code respectively; 2. The backscattered light signal generated in the forward propagation process is sent to the computer 5 for processing; the computer 5 uses the above backscattered light signal to synthesize a new backscattered light signal; the synthesized backscattered light signal has a higher spatial resolution It is the same as the backscattered light signal of a single light pulse in the sequence, and is stronger than that of a single pulse in terms of signal strength, and is proportional to the number of light pulses in the sequence.

Below are the embodiments given by the inventor:

1) computer 5 utilizes formula (2) to generate a group of Golay codes A and B, and their inverse code and

A ⁽ⁿ⁺¹⁾ = A ⁽ⁿ⁾ | B ⁽ⁿ⁾

(2)

${\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; |</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}$

是B⁽ⁿ⁾的反码，如果码B⁽ⁿ⁾是1，则码

是-1，反之如果码B⁽ⁿ⁾是-1，则码

是1；|是连接符，因此，生成的Golay码A和B，以及它们的反码

和的长度L是2的幂次方。Golay码A和B的自相关函数r_A(k)和r_B(k)的和具有如下特性：in

is the inverse code of B ⁽ⁿ⁾ , if the code B ⁽ⁿ⁾ is 1, then the code

is -1, otherwise if the code B ⁽ⁿ⁾ is -1, then the code

is 1; | is a connector, therefore, the generated Golay codes A and B, and their inverse

and The length L is a power of 2. The sum of the autocorrelation functions r _A (k) and r _B (k) of Golay codes A and B has the following characteristics:

r _A (k) + r _B (k) = 2Lδ _k (3)

in ${\mathrm{\&delta;}}_k=\left\{\begin{array}{cc}1& k=0\\ 0& k\&NotEqual;0\end{array}\right.---\left(4\right)$

Assuming that A ⁽⁰⁾ =1 and B ⁽⁰⁾ =1, then the 64-bit Golay codes A and B generated according to formula (2) are respectively:

A＝{111-111-11 111-1-1-11-1 111-111-11 -1-1-1111-11}

+{111-111-11 111-1-1-11-1 -1-1-11-1-11-1 111-1-1-11-1}

B＝{111-111-11 111-1-1-11-1 111-111-11 -1-1-1111-11}

+{-1-1-11-1-11-1 -1-1-1111-11 111-111-11 -1-1-1111-11}

Fig. 2 is the waveform of the above-mentioned 64-bit Golay codes A and B.

Fig. 3 is the autocorrelation function of above-mentioned 64-bit Golay code A and B and their autocorrelation function sum waveform, wherein Fig. 3 (a) is the waveform of Golay code A autocorrelation function, Fig. 3 (b) is Golay code B autocorrelation function The waveform of the correlation function, Figure 3(c) is the waveform of the sum of the autocorrelation functions of Golay codes A and B. It can be seen from Fig. 3(c) that the sum of the autocorrelation functions of 64-bit Golay codes A and B is δ.

和

转换成单极性的脉冲序列P_A，P_B，

和 2) computer 5 utilizes formula (5) with bipolar Golay code A and B, and their inverse code

and

converted into unipolar pulse trains P _A , P _B ,

and

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.75</span>}<span\; class="notranslate">\; \&times;</span>\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.25</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; A</span>}$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.75</span>}<span\; class="notranslate">\; \&times;</span>\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.25</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; B</span>}$

(5)

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.75</span>}<span\; class="notranslate">\; \&times;</span>\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.25</span>}<span\; class="notranslate">\; \&times;</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.75</span>}<span\; class="notranslate">\; \&times;</span>\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.25</span>}<span\; class="notranslate">\; \&times;</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; B</span>}}$

是长度等于L，每个码元均是1的脉冲序列。脉冲序列P_A，P_B，

和

的每个码元的值或是1，或是0.5。in

Is a pulse sequence whose length is equal to L and each symbol is 1. Pulse sequence P _A , P _B ,

and

The value of each symbol of is either 1 or 0.5.

和

的波形。Figure 4 shows pulse sequences _PA , P _B ,

and

waveform.

3) The computer 5 modulates the laser pulse generator 101 with the pulse sequence _PA . When the symbol value is 1, the peak power of the light pulse output by the laser pulse generator 101 is the maximum value allowed for output. When the symbol value is 0.5, the laser pulse The peak power of the light pulse output by the generator 101 is half of its maximum allowable output value.

4) The optical pulse sequence modulated by P _A propagates along the sensing fiber 2 to the output end, is collected by the optical fiber output optical power detection module [4], and is sent to the computer 5 for processing.

5) The computer 5 performs amplitude conversion on the optical pulse sequence signal collected by the optical fiber output optical power detection module 4 according to the following rules: if the value of a certain pulse in the optical pulse sequence signal corresponds to a symbol in _PA is 0.5, then the pulse The amplitude of the signal is multiplied by 2, otherwise unchanged.

The amplitude of the transformed optical pulse sequence signal is only related to the disturbance generated by pipeline leakage and intrusion events, thus eliminating the influence of the modulated signal _PA . Since the length L of the pulse sequence is a power of 2, it is more suitable for digital signal processing.

For example, P _A is coupled into the sensing fiber 2 and propagates forward along the fiber 2, assuming that it is disturbed by external events during the propagation, the output signal of fiber 2 is shown in Figure 5(a), then the transformed output signal is as Figure 5(b) shows. It can be seen from Figure 5 that the modulation signal Golay code A has been eliminated, and its output is only related to the interference generated by external events.

6) On the other hand, in the process of forward propagation along the sensing fiber 2, the light pulse sequence signal modulated by _PA continuously generates backscattered light, and the backscattered light travels backward along the fiber 2 and returns to the input end, and is absorbed by the backscattered light. Collect 3 to the scattered light power detection module and send to computer 5 for processing. Assuming that the response of the sensing fiber 2 to the backscattered light signal of a single light pulse is h _f , then when the input is an optical pulse train signal modulated by _PA , the corresponding backscattered light signal is the convolution of PA _and h _f , denoted as P _A *h _f .

和

代替P_A，重复步骤3)-6)，背向散射光功率检测模块3采集相应的背向散射光信号，并送计算机5进行处理。7) Use P _B , respectively,

and

Instead of _PA , repeat steps 3)-6), the backscattered light power detection module 3 collects the corresponding backscattered light signal, and sends it to the computer 5 for processing.

和

的背向散射光合成新的背向散射光信号的过程：Fig. 6 is that computer 5 utilizes _PA , P _B ,

and

The process of synthesizing a new backscattered light signal from the backscattered light:

的背向散射光信号相减，然后再与Golay码A进行相关运算，记作x_A (1) PA and _PA that computer 5 will collect

The backscattered light signal is subtracted, and then correlated with the Golay code A, denoted as x _A

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

(2) The computer [5] will collect P _B and The backscattered light signal is subtracted, and then correlated with the Golay code B, denoted as x _B

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

(3) Add the results obtained in steps (1) and (2), and the computer 5 obtains a synthetic backscattered light signal:

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; corr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; L</span>}{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}$

$<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}$

Therefore, the intensity of the synthesized backscattered light signal is L times that of the single-pulse backscattered light signal, and their spatial resolutions are the same.

In the distributed optical fiber sensor based on OTDR oil and gas pipeline leakage and intrusion detection, the present invention proposes to use Golay codes and their inverse code modulated optical pulse sequences as detection signals, so what propagates in the sensing optical fiber 2 is that the length L is a power of 2 power continuous light pulse train signal. Golay codes and their inverse code-modulated optical pulse sequences are coupled into the sensing fiber 2; during the forward propagation of the optical pulse sequence along the sensing optical fiber 2, its amplitude is modulated by the disturbance generated by pipeline leakage and intrusion events; At the output end of the sensing fiber 2, the optical pulse sequence signal is collected by the optical fiber output optical power detection module 4 and sent to the computer 5 for processing; the computer 5 first performs amplitude conversion on the optical pulse sequence signal to eliminate the modulation of the Golay code and their inverse code, The change of the output signal amplitude after transformation is only related to the interference of the external event on the sensing fiber 2; the computer 5 obtains the characteristics of the transmission loss change when the sensing fiber 2 is disturbed by the external event through spectrum analysis.

On the other hand, backscattered light is continuously generated during the forward propagation of the light pulse sequence along the sensing fiber 2 . The backscattered light propagates back along the optical fiber 2 and returns to the input end of the sensing optical fiber 2 . The computer 5 modulates the amplitude of the optical pulse signal output by the laser pulse generator 101 with the Golay code and their inverse code respectively; 2. The backscattered light signal produced in the forward propagation process is sent to the computer 5 for processing; the computer 5 uses the above-mentioned backscattered light signal to synthesize a new backscattered light signal; the synthetic backscattered light signal has the same spatial resolution as The backscattered light signal of a single light pulse in the sequence is the same, but stronger than that of a single pulse in terms of signal strength, and is proportional to the number of light pulses in the sequence.

Since the detection signal in the sensing fiber 2 is a continuous light pulse sequence, it is also a sampling signal of the loss of the sensing fiber 2 . Therefore, the sampling frequency of the loss of the sensing fiber 2 can be increased by reducing the pulse width in the optical pulse sequence, so that the system can analyze the characteristics of the additional loss of the sensing fiber 2 caused by external events in a larger spectral range; moreover, the optical pulse The reduction in width helps to improve the spatial resolution of the synthesized backscattered light signal. On the other hand, by increasing the number of pulses in the optical pulse sequence, increasing the intensity of the synthetic backscattered light signal and improving the signal-to-noise ratio, thereby increasing the distance of the distributed optical fiber sensor detection pipeline; and, by increasing the number of pulses in the sequence The number can increase the number of sampling points for the transmission loss of the sensing fiber 2, which is helpful for the analysis of the new loss characteristics on the sensing fiber 2.

Therefore, the method of the present invention can increase the distance of the distributed optical fiber sensor detection pipeline by enhancing the intensity of the backscattered light signal and improving the signal-to-noise ratio; Spectrum Scope analyzes the characteristics of the losses generated by pipeline leakage and third-party intrusion events on the sensing fiber 2, thereby improving the overall performance of distributed fiber optic sensors based on OTDR oil and gas pipeline leakage and intrusion detection.

Claims (9)

1. a method that improves the distributed fiberoptic sensor performance of oil and gas pipeline leakage and intrusion detection is characterized in that, may further comprise the steps:

1) near oil and gas pipes, with optical cable of the parallel laying of oil and gas pipes, utilize sensor fibre [2] as sensor, oil and gas pipeline leakage and third party's intrusion event are monitored in real time;

2), a back-scattering light testing module [3] and optical fiber Output optical power testing module [4] are set respectively at the two ends of sensor fibre [2];

Computer [5] is used Golay sign indicating number and their radix-minus-one complement modulated laser pulse oscillator [101] respectively, and what make laser pulse generator [101] output is that amplitude is by the continuous light pulse sequence of Golay sign indicating number with the modulation of their radix-minus-one complements;

The light pulse sequence of laser pulse generator [101] output is through isolator [101] and Coupler [103] is coupled into sensor fibre [2] and propagation forward in sensor fibre [2]; Output terminal in sensor fibre [2], Output optical power testing module [4] is gathered the light pulse sequence of sensor fibre [2] output, and send computer [5] to handle; Computer [5] carries out amplitude transformation to the pulse sequence signal of Output optical power testing module [4] output, eliminates the modulation of Golay sign indicating number and their radix-minus-one complements; Computer [5] is accomplished the measurement of sensor fibre [2] overall diameter total losses dynamic change and the judgement of fault type through the analysis to the optical fiber after the conversion [2] Output optical power signal;

The backscattering optical signal that the light pulse sequence that input end in sensor fibre [2], back-scattering light testing module [3] are gathered the modulation of Golay sign indicating number and their radix-minus-one complements respectively produces in the propagation process forward along sensor fibre [2], and send computer [5] to handle; Computer [5] utilizes above-mentioned backscattering optical signal to synthesize new backscattering optical signal; Synthetic backscattering optical signal aspect spatial resolution with sequence in backscattering optical signal identical of single light pulse; Aspect signal intensity; Strong than individual pulse, and be directly proportional with the number of light pulse in the sequence; Computer [5] is accomplished sensor fibre [2] and is gone up the static state of each point and the measurement and the location of dynamic loss through the analysis to the new backscattering optical signal that synthesizes;

3) analysis and the fusion of computer [5] through sensor fibre [2] is gone up lossy data, the pressure around the acquisition oil and gas pipes and the characteristic of oscillating signal are judged and the location oil and gas pipes is revealed and the generation of third party's intrusion event.

2. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; Described laser pulse generator [101] is laser diode or laser triode, and the width of the light pulse of its output and energy are controlled.

3. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; Sensor fibre in the described sensing optic cable [2] is SMF Single Mode Fiber or multi-mould optical fibre, and its transmission loss is responsive to deformation, pressure and oscillating signal.

4. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; Described Output optical power testing module [4] comprises optical power detector [401], amplification and low-pass filter [402], mould/number conversion and DSP digital signal processor [403] unit, is used to gather the light train pulse signal of sensor fibre [2] output.

5. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; Described back-scattering light testing module [3] comprises optical power detector [301], amplification and low-pass filter [302], mould/number conversion and DSP digital signal processor [303] unit, is used to gather the backscattering optical signal of sensor fibre.

6. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; What described laser pulse generator [101] was exported is continuous light pulse sequence, and the width of pulse is identical in the sequence, and amplitude is by Golay sign indicating number and their radix-minus-one complement modulation; The length of pulse is identical with the length of Golay sign indicating number and their radix-minus-one complements in the sequence, all is power powers of 2.

7. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; The light pulse sequence of described Golay sign indicating number and their radix-minus-one complements modulation is to be input to respectively at a certain time interval in the sensor fibre [2], and its minimum interval equals last light pulse produces at sensor fibre [2] output terminal in the sequence back-scattering light and turns back in sensor fibre [2] input end and the sequence time difference that first light pulse is input to sensor fibre [2].

8. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; Described Golay sign indicating number and their radix-minus-one complement are pseudo-random signals; Output terminal in sensor fibre [2], the pulse sequence signal that computer [5] is gathered Output optical power testing module [4] carries out amplitude transformation, eliminates the modulation of Golay sign indicating number and their radix-minus-one complements; The amplitude of conversion afterpulse sequence signal is only relevant with the disturbance that pipe leakage and third party's intrusion event produce.

9. the method for the distributed fiberoptic sensor performance of raising oil and gas pipeline leakage as claimed in claim 1 and intrusion detection; It is characterized in that; Described back-scattering light testing module [3] and Output optical power testing module [4] are worked simultaneously or are worked alone, and back-scattering light testing module [3] is accomplished sensor fibre [2] and gone up the static state of each point and the measurement and the locating function of dynamic loss; Output optical power testing module [4] is accomplished sensor fibre [2] and is gone up the measurement of total losses dynamic change and the decision-making function of fault type.

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