Fault positioning method of optical fiber communication link

Abstract

The invention provides a fault positioning method for an optical fiber communication link, and relates to the technical field of optical fiber communication, the same detection pulse signals are transmitted to each branch of the optical fiber communication link, reflectors with different coding modes are installed at the tail ends of the branches of the optical fiber communication link to respectively code the detection pulse signals transmitted to the reflectors, and the detection pulse signals are transmitted to the optical fiber communication link. The coding detection pulse signal is reflected; processing and analyzing the coded detection pulse signal reflected by each branch, and calculating the total coded pulse and the light current density; establishing a link fault judgment model based on the light current density, calculating an optical fiber communication link fault probability, and judging that a fault occurs when the fault probability exceeds a threshold value; and when the fault is judged to occur, fault positioning is performed on the branch where the reflector which does not receive the detection pulse signal is located, and the fault position is fed back and reported to the system, so that the accuracy of fault judgment of the optical fiber communication link is improved, and the misjudgment cost and the maintenance efficiency are reduced.

Description

Technical Field

[0001] The invention provides a method for locating a fault of an optical fiber communication link, and relates to the technical field of optical fiber communication. Background Art

[0002] Since its advent in the 1970s, fiber-optic communication technology has experienced rapid development and has now become the mainstay of global communication networks. With its advantages of high speed, large capacity, low loss, and anti-electromagnetic interference, fiber-optic communication technology has been widely used in telecommunications operator networks, data center interconnection, 5G and future 6G networks. With the continuous growth of data transmission demand, fiber-optic communication technology has been continuously innovated, and the transmission rate has developed from the initial several megabits per second (Mbps) to the current tens of trillions of bits per second (Tbps), which has greatly promoted the progress of the communications industry.

[0003] Although fiber-optic communication technology has many advantages, it is still difficult to avoid failures in practical applications. Fiber-optic communication failures may cause signal interruption, data loss, communication delays and other problems, seriously affecting the normal operation of the communication network and user experience. Therefore, in-depth research on fiber-optic communication failures and the development of effective fault location and maintenance optimization technologies are of great significance to improving the stability and reliability of communication networks. However, there are some shortcomings in the fault location methods of fiber-optic communication links in the prior art, mainly including the following aspects:

[0004] Cost and equipment requirements: Some fault location techniques, such as OTDR (Optical Time Domain Reflectometer), may require expensive specialized equipment, which increases the cost of maintenance and fault location.

[0005] Operational complexity: Some fault location methods may require professionals to perform operations and data analysis, which limits the speed and convenience of fault location.

[0006] Blind spots and limitations: OTDR technology has blind spots near both ends of the fiber link, which makes it difficult to locate faults at the beginning and end of the fiber link.

[0007] Data processing complexity: The detection pulse signal transmitted in the optical fiber link may be affected by many factors during the reflection process, such as the nonlinear effect of the optical fiber, signal attenuation, etc., which increases the complexity of data processing.

[0008] Fault type identification: Some fault location techniques may have difficulty distinguishing between different types of faults, such as fiber breaks, connector issues, or fiber bends.

[0009] Fault location accuracy: In some cases, the accuracy of fault location may not be sufficient to quickly find the fault point, especially when the fiber link is too long or the terrain is complex. Summary of the invention

[0010] In order to solve the above technical problems, the present invention proposes a method for locating a fault in an optical fiber communication link, comprising the following steps:

[0011] S1, transmitting the same detection pulse signal to each branch of the optical fiber communication link, installing reflectors with different encoding methods at the end of each branch of the optical fiber communication link to encode the detection pulse signal transmitted to the reflector respectively, and reflecting the encoded detection pulse signal;

[0012] S2, processing and analyzing the coded detection pulse signals reflected from each branch, and calculating the total coded pulse and photocurrent density;

[0013] S3. Based on the photocurrent density, a link fault judgment model is established to calculate the failure probability of the optical fiber communication link. When the failure probability exceeds the threshold, it is judged that a fault occurs;

[0014] S4. When it is determined that a fault occurs, the branch where the reflector that has not received the detection pulse signal is located is fault located, and the fault position is fed back to the system.

[0015] Furthermore, in step S2, the total coded pulse E(t,λ) received at time t is expressed as:

[0016]

[0017] Among them, λ is the initial wavelength of the detection pulse signal, A is the initial amplitude of the detection pulse signal, and a e is the insertion loss of the reflector, exp(-α e ) represents the amplitude attenuation after passing through the i-th reflector, λ i is the central wavelength of the coded detection pulse signal reflected back by the i-th signal, τ i is the time delay, δ(λ-λ i ) is the Dirichlet function, p(t-τ i ) is the pulse shape function.

[0018] Furthermore, the photocurrent i at time t PD (t) is expressed as:

[0019] i PD (t) = G|E(t,λ)| 2 +i n (t)

[0020] Where |E(t,λ)| 2 is the power of the total coded pulse signal, i n (t) is the noise current;

[0021] The photocurrent density γ is expressed as:

[0022]

[0023] Among them, the detection period is T c .

[0024] Furthermore, when a fiber optic communication link fails, the expectation is a and the variance is σ a , when the link is normal, the expectation is b and the variance is σ b , then P D is the probability of correctly detecting a failure in the optical fiber communication link, P FA is the false alarm probability when the optical fiber communication link is normal, and the expression is as follows:

[0025]

[0026] Among them, μ is the threshold current of the judgment comparator.

[0027] Furthermore, the link failure judgment model for judging the failure probability is defined as:

[0028]

[0029] When the failure probability P ODP When the threshold is exceeded, it is judged that a fault has occurred.

[0030] Furthermore, suppose that the initial fault wave surge propagates from the fault point F along the line to the detection points at both ends of MN at the same wave speed v and arrives at the detection points at both ends of M and N at the times T M , T N , then the distance L from the M end and the N end to the fault point F is obtained MF and L NF for:

[0031]

[0032] Wherein, L is the length between the M end and the N end.

[0033] Furthermore, in step S1, the reflector is a fiber Bragg grating reflector, and the number of Bragg gratings in each reflector is equal to the code weight of the codeword.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] Improve fault location accuracy: Based on the photocurrent density, a link fault judgment model is established to calculate the failure probability of the optical fiber communication link. When the failure probability exceeds the threshold, the fault is judged to have occurred. The accuracy of fault judgment is the highest, which helps to reduce false alarms.

[0036] The coded detection pulse signals reflected from each branch are processed and analyzed, and the total coded pulse and photocurrent density are calculated to provide corresponding data for fault judgment, increase data processing efficiency, and reduce the impact of interference on fault judgment. This helps to reduce the time and computing resources required for data processing and improve the response speed and efficiency of the entire verification system.

[0037] Improve user experience: Since this method can quickly and accurately locate faults in optical fiber communication links, the alarm is timely and accurate, which improves maintenance efficiency, reduces the cost of troubleshooting false alarms, and further improves the satisfaction of communication users. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0039] Figure 1 A schematic flow chart of a method for locating a fault in an optical fiber communication link according to the present invention;

[0040] Figure 2 is a schematic diagram of a Bragg grating reflector;

[0041] Figure 3 It is a schematic diagram of the distance between the fault point and the detection points at both ends of the line according to the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In the drawings of the specific embodiments of the present invention, in order to better and more clearly describe the working principles of the various components in the system, the connection relationship of the various parts in the device is shown, which only clearly distinguishes the relative position relationship between the various components, and cannot constitute a limitation on the signal transmission direction, connection sequence and structural size, size and shape of each part within the component or structure.

[0044] like Figure 1 The figure is a schematic flow chart of a method for locating a fault in an optical fiber communication link of the present invention. The method for locating a fault in an optical fiber communication link comprises the following steps:

[0045] S1. The same detection pulse signal is transmitted to each branch of the optical fiber communication link. A reflector with different encoding methods is installed at the end of each branch of the optical fiber communication link to encode the detection pulse signal transmitted to the reflector respectively, and reflect the encoded detection pulse signal.

[0046] Specifically, it is necessary to send a detection pulse signal with the same characteristics (such as power, wavelength, and pulse width) to each branch of the optical fiber communication link.

[0047] A reflector with a unique coding method is installed at the end of each fiber optic communication link branch. When the detection pulse signal reaches the end of the optical fiber, it will be encoded by the reflector and reflected back.

[0048] Preferably, the reflector is a fiber Bragg Grating (FBG) reflector, which can reflect optical signals of a specific wavelength, such as a detection optical signal, while allowing other wavelengths to pass, such as normal communication signals. When the detection pulse signal reaches the end of the optical fiber, it will be encoded and reflected back by these reflectors, thereby achieving real-time monitoring of the optical fiber link.

[0049] like Figure 2 The figure shows a schematic diagram of a Bragg grating reflector. The wavelength at which the incident light is reflected is called the Bragg wavelength. Optical signals of other wavelengths are hardly affected by the Bragg grating and will continue to be transmitted through the fiber grating.

[0050] In a preferred embodiment, the reflected coded detection pulse signal can be optically amplified and the power loss of the coded detection pulse signal in the optical fiber link can be compensated. After photoelectric conversion through the optical detector, information such as the pulse amplitude and wavelength of the received coded detection pulse signal can be extracted simultaneously, thereby performing the next step of data analysis and calculation.

[0051] S2. Process and analyze the coded detection pulse signals reflected from each branch, calculate the total coded pulse and photocurrent density, and provide corresponding data for fault judgment.

[0052] The detection pulse signal passes through the trunk input optical fiber, enters the branch distribution optical fiber, and reaches the reflector with a unique coding method at the corresponding end of each branch for encoding. The encoded detection pulse signal is reflected back to the receiving end of the trunk.

[0053] Specifically, there are w reflected coded detection pulse signals, each of which has a different wavelength and delay. Then the total coded pulse received by the receiving end of the trunk can be expressed as the superposition of multiple reflected coded detection pulse signals.

[0054] The total coded pulse E(t,λ) received at time t is expressed as:

[0055]

[0056] Among them, λ is the initial wavelength of the detection pulse signal, A is the initial amplitude of the detection pulse signal, and a e is the insertion loss of the reflector, which is a parameter describing the power reduction of the detection pulse signal when it passes through the reflector. It is related to the material and design of the reflector and the wavelength of the detection pulse signal; exp(-α e ) represents the amplitude attenuation after passing through the i-th reflector, λ i is the central wavelength of the coded detection pulse signal reflected back by the i-th signal, τ i is the time delay, δ(λ-λ i ) is the Dirichlet function, which is used to ensure that only the wavelength components matching the central wavelength of the i-th reflector are considered; P(t-τ i ) is the pulse shape function, which represents the pulse shape at time t.

[0057] It is important to explain that the number of Bragg gratings in each reflector is equal to the code weight of the codeword, which are two key parameters. The number of Bragg gratings determines the number of unique wavelengths that can be encoded, while the code weight of the codeword affects the capacity and performance of the system. Code weight refers to the number of non-zero elements in the codeword, which is directly related to the user capacity of the system and the management of multi-user interference. For example, in an OCDMA system, the larger the code weight of the codeword, the more users the system can support, but it may also increase multi-user interference.

[0058] When a branch distribution fiber fails, no coded detection pulse signal is returned. When other branch distribution fibers are working normally, the detection pulse signal transmitted in the fiber link is encoded and reflected back to the receiving end for decoding and analysis.

[0059] The decoded total coded pulse signal is converted into an electrical signal by a photodetector with a gain of G. The photocurrent i at time t PD (t) can be expressed as:

[0060] i PD (t) = G|E(t,λ)| 2 +i n (t)

[0061] where |E(t,λ)| 2 is the power of the total coded pulse signal, i n (t) is the noise current. Assuming that the polarization effect is ignored, all light pulse currents detected by the photodetector have consistent and independent statistics, so the noise terms can be linearly superimposed.

[0062] In order to evaluate the status of the optical fiber link, the detection period is T c The current signal of the photodetector is filtered and sampled within the observation window interval to calculate the photocurrent density.

[0063] The photocurrent density γ can be expressed as:

[0064]

[0065] S3. Based on the photocurrent density, a link fault judgment model is established to calculate the failure probability of the optical fiber communication link. When the failure probability exceeds the threshold, it is judged that a fault occurs.

[0066] The probability of correctly reporting a fiber optic communication link failure and the probability of incorrectly reporting a fiber optic communication link failure are both very important in detecting failures, and the two probabilities are inherently related.

[0067] Definition P D is the probability of correctly detecting a fault in the optical fiber communication link, μ is the threshold current of the judgment comparator; P FA is the false alarm probability when the optical fiber communication link is normal.

[0068] Assume that the photocurrent density γ obeys a Gaussian distribution with a mean and variance. When a fiber optic communication link fails, the mean is a and the variance is σ. a , when the link is normal, the expectation is b and the variance is σ b , then the expression is as follows:

[0069]

[0070] Among them, μ is the threshold current of the judgment comparator.

[0071] In an ideal detection system, P D The larger the value, the greater the FA As small as possible can achieve the desired result, and the link fault judgment model for judging the fault probability can be defined as:

[0072]

[0073] When the failure probability P ODP When the threshold is exceeded, it is judged that a fault has occurred, and the resulting fault judgment is the most accurate, which can reduce false alarms or missed alarms of fault points, reduce operating costs, and improve user satisfaction.

[0074] S4. According to the judgment result of the fault occurrence probability in step S3, the fault location is performed on the branch where the reflector that has not received the detection pulse signal is located, and the fault location is fed back to the system.

[0075] like Figure 3 As shown, the distance between the fault point and the detection points at both ends of the line is calculated by using the absolute time difference between the initial line wave surge generated at the fault location in the optical fiber communication link and reaching the detection points at both ends of the line.

[0076] Specifically, in a fiber optic communication link, when a fault occurs, the initial wave surge generated by the fault point will propagate to the detection points at both ends of the line at a certain speed. By calculating the absolute time difference between the two detection points receiving the wave surge, the distance between the fault point and the detection points at both ends of the line can be inferred.

[0077] Assume that the initial fault wave surge propagates from the fault point F along the line to the detection points at both ends of MN at the same wave speed and the time when it reaches the detection points at both ends of M and N is T M 、T N . According to the line relationship, it can be expressed as follows:

[0078]

[0079] Among them, L MF is the distance from the detection point at the M end to the fault point F, L NF is the distance from the detection point at the N end to the fault point F. L is the length between the lines MN, and v is the wave speed.

[0080] The distance from the M and N terminals to the fault point F can be obtained from the above formula:

[0081]

[0082] Finally, the fault location is fed back to the system.

[0083] This distance measurement method is not affected by other wave impedance discontinuities in the line and reflected waves from non-faulty lines, and has high distance measurement reliability. After the above method measures the specific fault location in the faulty line, it will issue a fault alarm to the system.

[0084] In a preferred embodiment, during the fault location process of the optical fiber communication link, to ensure that the transmitted pulse signal does not affect the normal communication, a low-power detection pulse signal may be used to reduce the interference with the normal communication.

[0085] Choose an appropriate test time, such as performing fault location testing during idle communication hours to avoid affecting normal communication traffic.

[0086] Preferably, wavelength division multiplexing (WDM) technology can be used to send the detection pulse signal and normal communication signal on different wavelengths to avoid mutual interference. If the optical fiber network is designed with a spare channel, the detection pulse signal can be sent on the spare channel without affecting the normal communication of the service channel.

[0087] In a preferred embodiment, during the fault location process of a fiber optic communication link, if a false alarm occurs, it can be achieved by using a variety of detection tools and methods, such as using an optical power meter to measure optical power, or using an OTDR (optical time domain reflectometer) to perform a more detailed link test.

[0088] Analyze the cause of the false alarm to determine whether it is due to environmental factors (such as temperature and humidity changes), equipment configuration errors, or excessive sensitivity of the detection system.

[0089] Check whether the environment of the fiber link has changed, such as new construction, vegetation growth, and other factors that may affect the detection results. Also, check whether the fiber connectors and equipment are clean, as dirt can also cause false alarms. Continuously monitor areas suspected of false alarms to see if there are persistent or recurring alarm signals.

[0090] In one embodiment, a computer device is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiments when executing the computer program.

[0091] In one embodiment, a computer-readable storage medium is provided, storing a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0092] In one embodiment, a computer program product or computer program is provided, the computer program product or computer program includes computer instructions, the computer instructions are stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps in the above-mentioned method embodiments.

[0093] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0094] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for locating a fault in an optical fiber communication link, characterized in that: The steps include: S1, transmitting the same detection pulse signal to each branch of the optical fiber communication link, installing reflectors with different encoding methods at the end of each branch of the optical fiber communication link to encode the detection pulse signal transmitted to the reflector respectively, and reflecting the encoded detection pulse signal; S2, processing and analyzing the coded detection pulse signals reflected from each branch, and calculating the total coded pulse and photocurrent density; S3. Based on the photocurrent density, a link fault judgment model is established to calculate the failure probability of the optical fiber communication link, and when the failure probability exceeds a threshold, it is determined that a fault occurs; S4. When it is determined that a fault occurs, the branch where the reflector that has not received the detection pulse signal is located is fault located, and the fault position is fed back to the system.

2. The fault location method according to claim 1, characterized in that: In step S2, the total encoding pulse E(t,λ) received at time t is expressed as: Among them, λ is the initial wavelength of the detection pulse signal, A is the initial amplitude of the detection pulse signal, and a e is the insertion loss of the reflector, exp(-α e ) represents the amplitude attenuation after passing through the i-th reflector, λ i is the central wavelength of the coded detection pulse signal reflected back by the i-th signal, τ i is the time delay, δ(λ-λ i ) is the Dirichlet function, P(t-τ i ) is the pulse shape function.

3. The fault location method according to claim 2, characterized in that: The photocurrent i at time t PD (t) is expressed as: i PD (t)=G|E(t,λ)| 2 +i n (t) where |E(t,λ)| 2 is the power of the total coded pulse signal, i n (t) is the noise current; The photocurrent density γ is expressed as: Among them, the detection period is T c .

4. The fault location method according to claim 3, characterized in that: When a fiber optic communication link fails, the expectation is a and the variance is σ a , when the link is normal, the expectation is b and the variance is σ b , then P D is the probability of correctly detecting a failure in the optical fiber communication link, P FA is the false alarm probability when the optical fiber communication link is normal, and the expression is as follows: Among them, μ is the threshold current of the judgment comparator.

5. The fault location method according to claim 4, characterized in that: The link failure judgment model for judging the failure probability is defined as: When the failure probability P ODP When the threshold is exceeded, it is judged that a fault has occurred.

6. The fault location method according to claim 1, characterized in that: In step S4, it is assumed that the initial fault wave surge propagates from the fault point F along the line to the detection points at both ends of MN at the same wave speed v and the time when it reaches the detection points at both ends of M and N is T respectively. M 、T N , then the distance L from the M end and the N end to the fault point F is obtained MF and L NF for: Wherein, L is the length between the M end and the N end.

7. The fault location method according to claim 1, characterized in that: In the step S1, the reflector is a fiber Bragg grating reflector, and the number of Bragg gratings in each reflector is equal to the code weight of the codeword.

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