CN116318384A - Optical communication network fault monitoring system and method - Google Patents
Optical communication network fault monitoring system and method Download PDFInfo
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Abstract
The invention discloses an optical communication network fault monitoring system and method, comprising a control module, an OTDR module, an optical power module, a wavelength division multiplexer, an optical splitter, an optical switch and an upper computer, wherein the optical fiber to be tested comprises a working fiber and a standby fiber, the optical splitter transmits a sensing optical signal and a communication optical signal, the wavelength of the sensing optical signal is different from that of the communication optical signal, the wavelength division multiplexer realizes the splitting and the combining of the optical signals with different wavelengths in the same fiber core, the optical communication network can be effectively monitored, when the optical power of the optical fiber to be tested is abnormal, the upper computer is reported with an abnormal event and switches an optical path to the OTDR module for access, all the optical fibers to be tested are traversed to obtain OTDR curves of all the optical fibers to be tested, when the OTDR curves are abnormal, the optical power module is monitored, the fiber core number and the abnormal event distance corresponding to the abnormal OTDR curve are transmitted to the upper computer, the fault monitoring quality of the optical communication network is effectively improved, and the working stability of the optical communication network is ensured.
Description
Technical Field
The invention belongs to the technical field of optical fiber communication, and particularly relates to a system and a method for monitoring faults of an optical communication network.
Background
In recent years, with the development of information technology, the speed requirement of people on broadband networks is higher and higher, especially, network televisions, network games, online video and video downloading and the like, and the dependence of people on high bandwidth requirements and networks is increasingly raised. At high speed bandwidth requirements, conventional twisted pair transmission networks have failed to meet the requirements at all, in which case all-optical networks have evolved.
Once an optical fiber line fails, huge economic losses are caused, so that once the optical fiber line fails, an optical cable must be effectively repaired in time, and an important problem at present is how to quickly and accurately solve the optical cable obstacle. Currently, there is a certain progress in monitoring and locating optical fiber faults, for example, monitoring and locating faults can be performed by using a western system, and an electro-optical measurement device can be installed at the optical cable end to periodically measure attenuation of the optical cable. Because these methods still have the problem of inaccurate positioning and do not achieve the intended purpose, there is a need to improve the quality of fault monitoring of the optical fiber network.
Disclosure of Invention
In view of the above, the present invention provides an optical communication network fault monitoring system and method capable of improving the efficiency of monitoring faults of a communication network and rapidly locating fault points, so as to solve the above-mentioned technical problems.
In a first aspect, the present invention provides an optical communication network fault monitoring system, including a control module, an OTDR module, an optical power module, a wavelength division multiplexer, an optical splitter, an optical switch and an upper computer, where the upper computer, the optical power module are connected with the control module, the optical switch is connected with the wavelength division multiplexer, the optical power module, the upper computer is connected with the OTDR module, the control module, the wavelength division multiplexer is connected with an optical fiber to be tested in the optical communication network, where the optical fiber to be tested includes a working fiber and a standby fiber, the optical splitter is used for transmitting a sensing optical signal and a communication optical signal, wavelengths of the sensing optical signal and the communication optical signal are different, and the wavelength division multiplexer is used for implementing splitting and multiplexing of optical signals with different wavelengths in the same fiber core;
under the working mode of the standby fiber, the control module controls the optical switch and the OYDR module to inject test light into the fiber core to be tested in a preset period;
in the working mode of the working fiber, the optical splitter divides and takes 5% of communication light in the working fiber to transmit to the optical power module, the optical power module monitors and uploads the optical power intensity of the working fiber core in real time, and if the optical power value in the optical fiber is greater than a threshold value, the optical power module judges that no fault point exists in the optical fiber to be detected; if the optical power intensity in the optical fiber to be tested is lower than a threshold value, judging that a fault point exists in the optical fiber, wherein the control module is used for driving the optical switch to the fault fiber core, starting the OTDR module to inject test light into the fault fiber core, uploading OTDR characteristic curve data to the upper computer, and analyzing the type and the distance of an event point by the upper computer through the curve data so as to realize real-time monitoring of the optical fiber fault.
As a further improvement of the above technical solution, starting the OTDR module to inject test light into the failed fiber core, and then uploading OTDR characteristic curve data to the host computer, including:
the preset OTDR module tests the optical power as P (0), and the expression of the optical power P (Z) reaching the Z point after the transmission loss of the optical fiber to be tested is P (Z) =P (0) ×10 -(αZ/10) Rayleigh scattering occurs at the Z point, where γ (Z) is the back scattering coefficient at Z, denoted γ (Z) = (uT/2) α γ S, wherein S represents the ratio of the back scattered power to the total Rayleigh scattered power, alpha γ Representing the rayleigh scattering system, the expression of the backscattering power at z=0 is P γ (0) =p (0) γ (0), and determining the average attenuation coefficient as the expression corresponding to the rayleigh scattering and backscattering power
The whole optical fiber is desirably uniform and continuous, and when gamma (0) =gamma (Z), the average attenuation coefficient between 0 and Z can be expressed as +.>
The expression for calculating the relation between loss and optical fiber position from the light velocity is +.>
Where t represents the time interval between the time of the transmitted signal and the time of the received reflected signal.
As a further improvement of the above technical solution, wavelengths of the sensing optical signal and the communication optical signal are different, and the wavelength division multiplexer is configured to implement splitting and combining of optical signals with different wavelengths transmitted in the same fiber core, including:
forming a space grating in a fiber core by adopting a fiber Bragg grating, and enabling forward transmission energy to be given to the backward transmission fiber core mode by coupling between a fiber core mode of forward transmission and a fiber core mode of backward transmission of the grating so as to form reflection of incident waves, wherein the expression that the reflection center wavelength is Bragg wavelength is lambda B ＝2n eff Λ, wherein n eff The refractive index of the fiber core of the fiber to be measured to the center wavelength is shown, and Λ is the grating period.
As a further improvement of the technical scheme, the upper computer analyzes the type and the distance of the event point through curve data so as to realize real-time monitoring of the optical fiber faults, and the method comprises the following steps:
when abnormality is detected, the position of the fault point is rapidly positioned after the line fault occurs, the actual geographic position is matched, the geographic position of the fault point is displayed in a visual map form within 30 seconds, and alarm information is sent out.
As a further improvement of the above technical solution, the measurement of optical fiber faults is performed by using communication signals in a communication network, in the digital signal processing, the correlation function is a measure of the similarity between two signals, the correlation function includes cross correlation and autocorrelation, the cross correlation function reflects the correlation of different variables, i.e. signal x (n), signal y (n) at two different moments n 1 、n 2 The degree of correlation between the values; the autocorrelation function is the cross correlation of a signal function with itself at different points in time, i.e. the random signal x (n) is at any two different times n 1 、n 2 The degree of correlation between the values;
firstly, keeping x (n) motionless, shifting y (n) rightwards for m sampling periods to obtain y (n-m), multiplying x (n) and y (n-m) and summing, and finally obtaining a cross-correlation function r xy (m) a value at m time, which value reflectsThe degree of similarity of the two signals, x (n) and y (n-m), is given by
If x (n) =y (n), an autocorrelation function of x (n) can be obtained, denoted as r xx (m), i.e.)>
If the signal x (n) is a random signal, the autocorrelation function of x (n) can be expressed as +.>
Where k represents the normalized coefficient, there is a correlation peak at the delay position.
As a further improvement of the above technical solution, if all the communication signals in the optical network are periodic signals, a plurality of peaks will appear in the correlation curve, and the time interval between every two adjacent correlation peaks is the period of the communication signal;
if the communication signals in the optical network are all encrypted random signals, one correlation peak exists in the correlation curve of the random signals, the position of the correlation peak corresponds to delay time, if the communication signals in the optical network are complex signals overlapped by periodic signals and random signals, the correlation curve has correlation peaks, the maximum peak corresponds to delay time, the position of the highest peak of the cross-correlation curve is determined to correspond to the delay time, so that the delay time of two columns of signals is determined, and then the position of the optical fiber with faults can be accurately positioned by a speed distance formula.
As a further improvement of the above technical solution, the measurement of the optical fiber fault is performed using communication signals in the communication network. Comprising the following steps:
the reference optical communication signal at the beginning of transmission is preset to be f (t), the optical communication signal reflected back after encountering a fault point is af (t+tau), wherein the mixing coefficient of the attenuation of the optical fiber and the signal attenuation caused by the reflection of the fault point is a, the delay time is tau, and the mixed coefficient is a parameter to be solvedThe parameter is τ, i.e
Based on the time τ, if D fault Is the position of the fault point of the optical fiber, v is the propagation speed of laser in the optical fiber, and the position calculation expression of the fault point is D fault =vτ/2, the exact location of the fiber fault point is finally determined to achieve fiber fault localization.
As a further improvement of the technical scheme, the upper computer comprises an electronic map, a database and background software, when data analyzed by the upper computer analysis demodulator disappear, an optical fiber line fault occurs, an optical switch is adopted to switch to an optical fiber line to be detected, the reflected wave of which disappears, and the specific length of the optical fiber from the incident light end of the OTDR module is calculated.
As a further improvement of the technical scheme, comparing the calculated length with the pre-stored length pre-stored in the upper computer, judging whether an optical fiber line fault occurs, if the line fault occurs, matching the optical fiber interruption length with specific geographic information in the upper computer, displaying the result on an electronic map in a visual graph mode, and giving an optical fiber fault alarm.
In a second aspect, the present invention also provides a method for monitoring faults of an optical communication network, including the following steps:
reporting an abnormal event to an upper computer and switching an optical path to an OTDR module for access when the optical power of the optical fibers to be detected is abnormal in a preset period, and traversing all the optical fibers to be detected to obtain OTDR curves of all the optical fibers to be detected;
when the abnormality of the OTDR curve is monitored, switching to the optical power module, and sending the fiber core number and the abnormal event distance corresponding to the abnormal OTDR curve to the upper computer.
The invention provides a fault monitoring system and a fault monitoring method for an optical communication network, which can effectively monitor the optical communication network by arranging a control module, an OTDR module, an optical power module, a wavelength division multiplexer, an optical splitter, an optical switch and an upper computer, report an abnormal event to the upper computer when the optical power of an optical fiber to be detected is abnormal, switch an optical path to the OTDR module for access, traverse all the optical fibers to be detected so as to obtain OTDR curves of all the optical fibers to be detected, switch to the optical power module when the OTDR curves are abnormal, and send the fiber core numbers and the abnormal event distances corresponding to the abnormal OTDR curves to the upper computer, thereby effectively improving the fault monitoring quality of the optical communication network and ensuring the working stability of the optical communication network.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of an optical communication network fault monitoring system provided by the present invention;
fig. 2 is a flowchart of an optical communication network fault monitoring method provided by the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
Referring to fig. 1, the invention provides an optical communication network fault monitoring system, which comprises a control module, an OTDR module, an optical power module, a wavelength division multiplexer, an optical splitter, an optical switch and an upper computer, wherein the upper computer, the optical power module and the optical power module are connected with the control module, the optical switch is connected with the wavelength division multiplexer and the optical power module, the upper computer is connected with the OTDR module and the control module, the wavelength division multiplexer is connected with an optical fiber to be tested in the optical communication network, the optical fiber to be tested comprises a working fiber and a standby fiber, the optical splitter is used for transmitting a sensing optical signal and a communication optical signal, the wavelength of the sensing optical signal is different from the wavelength of the communication optical signal, and the wavelength division multiplexer is used for realizing the splitting and the multiplexing of optical signals with different wavelengths in the same fiber core;
under the working mode of the standby fiber, the control module controls the optical switch and the OYDR module to inject test light into the fiber core to be tested in a preset period;
in the working mode of the working fiber, the optical splitter divides and takes 5% of communication light in the working fiber to transmit to the optical power module, the optical power module monitors and uploads the optical power intensity of the working fiber core in real time, and if the optical power value in the optical fiber is greater than a threshold value, the optical power module judges that no fault point exists in the optical fiber to be detected; if the optical power intensity in the optical fiber to be tested is lower than a threshold value, judging that a fault point exists in the optical fiber, wherein the control module is used for driving the optical switch to the fault fiber core, starting the OTDR module to inject test light into the fault fiber core, uploading OTDR characteristic curve data to the upper computer, and analyzing the type and the distance of an event point by the upper computer through the curve data so as to realize real-time monitoring of the optical fiber fault.
In this embodiment, starting the OTDR module to inject test light into the failed fiber core, and then uploading OTDR characteristic curve data to the host computer includes: the preset OTDR module tests the optical power as P (0), and the expression of the optical power P (Z) reaching the Z point after the transmission loss of the optical fiber to be tested is P (Z) =P (0) ×10 -(αZ/10) Rayleigh scattering occurs at the Z point, where γ (Z) is the back scattering coefficient at Z, denoted γ (Z) = (uT/2) α γ S, wherein S represents the ratio of the back scattered power to the total Rayleigh scattered power, alpha γ Representing the rayleigh scattering system, the expression of the backscattering power at z=0 is P γ (0) =p (0) γ (0), and determining the average attenuation coefficient as the expression corresponding to the rayleigh scattering and backscattering power
The whole optical fiber is desirably uniform and continuous, and when gamma (0) =gamma (Z), the average attenuation coefficient between 0 and Z can be obtained by the expression
The expression for calculating the relation between loss and optical fiber position from the light velocity is +.>
Where t represents the time interval between the time of the transmitted signal and the time of the received reflected signal.
It should be noted that, the wavelengths of the sensing optical signal and the communication optical signal are different, and the wavelength division multiplexer is used for implementing the splitting and combining of the optical signals with different wavelengths transmitted in the same fiber core, including: forming a space grating in a fiber core by adopting a fiber Bragg grating, and enabling forward transmission energy to be given to the backward transmission fiber core mode by coupling between a fiber core mode of forward transmission and a fiber core mode of backward transmission of the grating so as to form reflection of incident waves, wherein the expression that the reflection center wavelength is Bragg wavelength is lambda B ＝2n eff Λ, wherein n eff The refractive index of the fiber core of the fiber to be measured to the center wavelength is shown, and Λ is the grating period. The fresnel reflection is caused by some points with abrupt refractive index changes in the optical fiber, so that the fresnel reflection is discrete, and the points capable of generating the fresnel reflection are caused by the abrupt refractive index changes caused by the change of elements such as glass and air gaps, and at these special points, strong back scattered light is reflected, and the fresnel reflection can be generated at the fracture surface of the light, the connector, the optical fiber break, and the like. OTDR (Optical Time Domain Reflectometer) is an optical time domain reflectometer, is a precise photoelectric integrated instrument for testing the integrity of an optical cable, is mainly used for evaluating the length of the optical fiber, the connection attenuation and the transmission attenuation of the optical fiber, can realize the fault location of the optical fiber, and is generally used for the maintenance and construction of the optical cable.
In addition, OTDR works indirectly, using a unique optical phenomenon of back-scattered light, as compared to an optical power module that directly measures the loss of a fiber optic cable device, and measures with reflected light from a connection device or a broken, interrupted fiber end, thereby indirectly measuring the loss. The OTDR works like a radar, it sends out a test signal along the fiber under test, and observes and analyzes the return signal, repeats the test process and averages the results, and displays the results in the form of a trace. The OTDR measures only the scattered light emitted by itself, and the back-scattered signal can show the attenuation degree, i.e. loss/distance, of the fiber, and its trajectory is a downward curve, indicating the back-scattered power reduction. The OTDR module detects optical fiber faults by utilizing the Rayleigh scattering and Fresnel reflection principles generated when light is transmitted in different optical fibers, and is a common instrument in optical fiber maintenance. The OTDR can measure the type and distance of fault points in the optical fiber, and can realize various sensing detection such as optical fiber temperature detection, stress detection and the like by adopting various scattering of light in the optical fiber.
It should be understood that the optical fiber fault monitoring hardware device is installed on an optical fiber distribution frame and connected in series into an optical fiber to be tested, 5% of the optical fiber communication light is taken as test light by a beam splitter in the device, an optical power module is adopted to monitor the optical power value of 5% of the communication light in real time, and if the optical power value is lower than a threshold value, the optical fiber fault is judged to exist in the optical fiber. The control module is used for controlling the optical switch and the WDM to connect the OTDR into the fault optical fiber, controlling the OTDR module to inject test light into the fault optical fiber core, and transmitting the measured OTDR characteristic curve information back to an upper computer of the machine room. Therefore, operation and maintenance scheduling personnel can timely repair the optical fiber line when the optical fiber line breaks down in a machine room until the optical fiber core breaks down, and loss caused by the optical fiber fault is reduced to the greatest extent.
Optionally, the upper computer analyzes the event point type and the distance according to the curve data to realize real-time monitoring of the optical fiber fault, including:
when abnormality is detected, the position of the fault point is rapidly positioned after the line fault occurs, the actual geographic position is matched, the geographic position of the fault point is displayed in a visual map form within 30 seconds, and alarm information is sent out.
In this embodiment, the communication signals in the communication network are used to measure the optical fiber fault, and in the digital signal processing, the correlation function is a measure of the similarity between two signals, and includes cross correlation and autocorrelation, where the cross correlation function reflects the correlation of different variables, i.e., the signal x (n), the signal y (n), at two different times n 1 、n 2 The degree of correlation between the values; the autocorrelation function is the cross correlation of a signal function with itself at different points in time, i.e. the random signal x (n) is at any two different times n 1 、n 2 The degree of correlation between the values; firstly, keeping x (n) motionless, shifting y (n) rightwards for m sampling periods to obtain y (n-m), multiplying x (n) and y (n-m) and summing, and finally obtaining a cross-correlation function r xy (m) a value at m time reflecting the degree of similarity of the two signals, x (n) and y (n-m), i.e
If x (n) =y (n), an autocorrelation function of x (n) can be obtained, denoted as r xx (m), i.e.)>
If the signal x (n) is a random signal, the autocorrelation function of x (n) can be expressed as +.>
Where k represents the normalized coefficient, there is a correlation peak at the delay position.
It should be noted that, if all the communication signals in the optical network are periodic signals, a plurality of peaks will appear in the correlation curve, and the time interval between every two adjacent correlation peaks is the period of the communication signal; if the communication signals in the optical network are all encrypted random signals, one correlation peak exists in the correlation curve of the random signals, the position of the correlation peak corresponds to delay time, if the communication signals in the optical network are complex signals overlapped by periodic signals and random signals, the correlation curve has correlation peaks, the maximum peak corresponds to delay time, the position of the highest peak of the cross-correlation curve is determined to correspond to the delay time, so that the delay time of two columns of signals is determined, and then the position of the optical fiber with faults can be accurately positioned by a speed distance formula.
Optionally, the measurement of the fiber fault is performed using a communication signal in the communication network. Comprising the following steps:
the reference optical communication signal at the beginning of transmission is preset as d (t), the optical communication signal reflected back after encountering a fault point is af (t+tau), wherein the mixing coefficient of the attenuation of the optical fiber and the signal attenuation caused by the reflection of the fault point is a, the delay time is tau, the reference optical communication signal is a parameter to be solved, and the parameter is tau can be calculated according to a related formula, namely
Based on the time τ, if D fault Is the position of the fault point of the optical fiber, v is the propagation speed of laser in the optical fiber, and the position calculation expression of the fault point is D fault =vτ/2, the exact location of the fiber fault point is finally determined to achieve fiber fault localization.
In this embodiment, after the OTDR module tests the emission distance of the optical fiber terminal from the OTDR test light, the matching between the geographical position and the optical fiber length is achieved, and the specific optical fiber fault occurrence position is located. When the system monitors abnormality, the position of the fault point can be rapidly positioned after the line fault occurs, the fault point is matched with the actual geographic position, the geographic position of the fault point is displayed in a visual map form within 30 seconds, and alarm information is sent out, so that the optical cable maintenance personnel can rapidly repair the optical cable. Besides realizing real-time fault alarm, when no fault occurs, the optical fiber historical data in the optical fiber network needs to be stored in an upper computer, so that later-stage consulting and analyzing of maintenance personnel are facilitated. When the operation of the optical cable line has no interruption fault, the optical cable line can be set by maintenance personnel, so that roll calling, period and real-time test of the optical cable are realized.
Optionally, the upper computer comprises an electronic map, a database and background software, when the data analyzed by the upper computer analysis demodulator disappear, an optical fiber line fault occurs, an optical switch is adopted to switch to an optical fiber line to be detected, the reflected wave disappears, and the specific length of the optical fiber from the incident light end of the OTDR module is calculated.
In this embodiment, the calculated length is compared with a pre-stored length pre-stored in the upper computer, whether an optical fiber line fault occurs is determined, if the line fault occurs, the optical fiber interruption length is matched with specific geographic information in the upper computer, the result is displayed on an electronic map in a visual pattern manner, and an optical fiber fault alarm is made, so that the timeliness and reliability of optical fiber fault monitoring are improved.
Referring to fig. 2, the invention further provides a method for monitoring faults of an optical communication network, which comprises the following steps:
s1: reporting an abnormal event to an upper computer and switching an optical path to an OTDR module for access when the optical power of the optical fibers to be detected is abnormal in a preset period, and traversing all the optical fibers to be detected to obtain OTDR curves of all the optical fibers to be detected;
s2: when the abnormality of the OTDR curve is monitored, switching to the optical power module, and sending the fiber core number and the abnormal event distance corresponding to the abnormal OTDR curve to the upper computer.
In this embodiment, the OTDR module sends optical pulses to the optical fiber to be tested according to a certain period, samples, quantizes and encodes the backscattered signal from the optical fiber according to a certain rate, and finally stores and displays the backscattered signal. The meter has inherent errors, generally including scale errors and resolution errors, and the number of sampling points of the OTDR directly influences the resolution of the distance. The OTDR test pulse can influence the test result, the energy of the OTDR module output test pulse is related to the setting of the width, the wider the pulse width is, the larger the output energy is, the farther the OTDR can test the distance range, but at the same time, the larger the dead zone of the event is, the test precision and the resolution are reduced, and the resolution is improved through the longitudinal and transverse amplifying function of the OTDR so as to reduce the reading and the measuring error.
It should be understood that by setting the control module, the OTDR module, the optical power module, the wavelength division multiplexer, the optical splitter, the optical switch and the upper computer, the optical communication network can be effectively monitored, when the optical power of the optical fiber to be detected is abnormal, an abnormal event is reported to the upper computer, the optical path is switched to the OTDR module for access, all the optical fibers to be detected are traversed to obtain OTDR curves of all the optical fibers to be detected, when the OTDR curves are abnormal, the optical power module is switched to, and the fiber core number and the abnormal event distance corresponding to the abnormal OTDR curves are sent to the upper computer, so that the fault monitoring quality of the optical communication network can be effectively improved, and the working stability of the optical communication network is ensured.
Any particular values in all examples shown and described herein are to be construed as merely illustrative and not a limitation, and thus other examples of exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
The above examples merely represent a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the present invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (10)
1. The optical communication network fault monitoring system is characterized by comprising a control module, an OTDR module, an optical power module, a wavelength division multiplexer, an optical splitter, an optical switch and an upper computer, wherein the upper computer, the optical power module and the optical power module are connected with the control module, the optical switch is connected with the wavelength division multiplexer and the optical power module, the upper computer is connected with the OTDR module and the control module, the wavelength division multiplexer is connected with an optical fiber to be detected in an optical communication network, the optical fiber to be detected comprises a working fiber and a standby fiber, the optical splitter is used for transmitting a sensing optical signal and a communication optical signal, the wavelength of the sensing optical signal is different from that of the communication optical signal, and the wavelength division multiplexer is used for realizing the division and the combination of optical signals with different wavelengths in the same fiber core;
under the working mode of the standby fiber, the control module controls the optical switch and the OYDR module to inject test light into the fiber core to be tested in a preset period;
in the working mode of the working fiber, the optical splitter divides and takes 5% of communication light in the working fiber to transmit to the optical power module, the optical power module monitors and uploads the optical power intensity of the working fiber core in real time, and if the optical power value in the optical fiber is greater than a threshold value, the optical power module judges that no fault point exists in the optical fiber to be detected; if the optical power intensity in the optical fiber to be tested is lower than a threshold value, judging that a fault point exists in the optical fiber, wherein the control module is used for driving the optical switch to the fault fiber core, starting the OTDR module to inject test light into the fault fiber core, uploading OTDR characteristic curve data to the upper computer, and analyzing the type and the distance of an event point by the upper computer through the curve data so as to realize real-time monitoring of the optical fiber fault.
2. The optical communication network fault monitoring system of claim 1, wherein activating the OTDR module to inject test light into a faulty fiber core and then uploading OTDR characteristic curve data to the host computer comprises:
the preset OTDR module tests the optical power as P (0), and the expression of the optical power P (Z) reaching the Z point after the transmission loss of the optical fiber to be tested is P (Z) =P (0) ×10 -(αZ/10) Rayleigh scattering occurs at the Z point, where γ (Z) is the back scattering coefficient at Z, denoted γ (Z) = (uT/2) α γ S, wherein S represents the ratio of the back scattered power to the total Rayleigh scattered power, alpha γ Representing the rayleigh scattering system, the expression of the backscattering power at z=0 is P γ (0) =p (0) γ (0), and determining the average attenuation coefficient as the expression corresponding to the rayleigh scattering and backscattering power
The whole optical fiber is desirably uniform and continuous, and when gamma (0) =gamma (Z), the average attenuation coefficient between 0 and Z can be expressed as +.>
The expression for calculating the relation between loss and optical fiber position from the light velocity is +.>
Where t represents the time interval between the time of the transmitted signal and the time of the received reflected signal.
3. The optical communication network fault monitoring system according to claim 1, wherein wavelengths of the sensing optical signal and the communication optical signal are different, and the wavelength division multiplexer is configured to implement splitting and combining of optical signals with different wavelengths transmitted in the same fiber core, and includes:
forming a space grating in a fiber core by adopting a fiber Bragg grating, and enabling forward transmission energy to be given to the backward transmission fiber core mode by coupling between a fiber core mode of forward transmission and a fiber core mode of backward transmission of the grating so as to form reflection of incident waves, wherein the expression that the reflection center wavelength is Bragg wavelength is lambda B ＝2n eff Λ, wherein n eff The refractive index of the fiber core of the fiber to be measured to the center wavelength is shown, and Λ is the grating period.
4. The optical communication network fault monitoring system according to claim 1, wherein the upper computer analyzes the event point type and the distance through curve data to realize real-time monitoring of the optical fiber fault, and the system comprises:
when abnormality is detected, the position of the fault point is rapidly positioned after the line fault occurs, the actual geographic position is matched, the geographic position of the fault point is displayed in a visual map form within 30 seconds, and alarm information is sent out.
5. The optical communication network failure monitoring system of claim 4, further comprising:
the method adopts communication signals in a communication network to measure optical fiber faults, and in digital signal processing, a correlation function is a measure of the similarity degree between two signals, and comprises cross correlation and autocorrelation, and the cross correlation function reflects the correlation of different variablesI.e. signal x (n), signal y (n) at two different moments in time n 1 、n 2 The degree of correlation between the values; the autocorrelation function is the cross correlation of a signal function with itself at different points in time, i.e. the random signal x (n) is at any two different times n 1 、n 2 The degree of correlation between the values;
firstly, keeping x (n) motionless, shifting y (n) rightwards for m sampling periods to obtain y (n-m), multiplying x (n) and y (n-m) and summing, and finally obtaining a cross-correlation function r xy (m) a value at m time reflecting the degree of similarity of the two signals, x (n) and y (n-m), i.e
If x (n) =y (n), an autocorrelation function of x (n) can be obtained, denoted as r xx (m), i.e.)>
If the signal x (n) is a random signal, the autocorrelation function of x (n) can be expressed as +.>
Where k represents the normalized coefficient, there is a correlation peak at the delay position.
6. The optical communication network failure monitoring system according to claim 5, wherein if all the communication signals in the optical network are periodic signals, a plurality of peaks appear in the correlation curve, and the time interval between every two adjacent correlation peaks is the period of the communication signal;
if the communication signals in the optical network are all encrypted random signals, one correlation peak exists in the correlation curve of the random signals, the position of the correlation peak corresponds to delay time, if the communication signals in the optical network are complex signals overlapped by periodic signals and random signals, the correlation curve has correlation peaks, the maximum peak corresponds to delay time, the position of the highest peak of the cross-correlation curve is determined to correspond to the delay time, so that the delay time of two columns of signals is determined, and then the position of the optical fiber with faults can be accurately positioned by a speed distance formula.
7. The optical communication network fault monitoring system of claim 5 wherein the measurement of the fiber fault is performed using communication signals in the communication network. Comprising the following steps:
the reference optical communication signal at the beginning of transmission is preset to be f (t), the optical communication signal reflected back after encountering a fault point is af (t+tau), wherein the mixing coefficient of the attenuation of the optical fiber and the signal attenuation caused by the reflection of the fault point is a, the delay time is tau, the reference optical communication signal is a parameter to be solved, and the parameter is tau can be calculated according to a related formula, namely
Based on the time τ, if D fault Is the position of the fault point of the optical fiber, v is the propagation speed of laser in the optical fiber, and the position calculation expression of the fault point is D fault =vτ/2, the exact location of the fiber fault point is finally determined to achieve fiber fault localization.
8. The optical communication network fault monitoring system according to claim 1, wherein the upper computer comprises an electronic map, a database and background software, when the data analyzed by the analysis demodulator of the upper computer disappears, an optical fiber line fault occurs, the optical switch is adopted to switch to an optical fiber line to be detected, the reflected wave of which disappears, and the specific length of the optical fiber from the incident light end of the OTDR module is calculated.
9. The optical communication network fault monitoring system according to claim 8, wherein the calculated length is compared with a pre-stored length pre-stored in an upper computer, whether an optical fiber line fault occurs is judged, if the line fault occurs, the optical fiber interruption length is matched with specific geographic information in the upper computer, the result is displayed on an electronic map in a visual pattern manner, and an optical fiber fault alarm is made.
10. An optical communication network failure monitoring method of an optical communication network failure monitoring system according to any one of claims 1-9, comprising the steps of:
reporting an abnormal event to an upper computer and switching an optical path to an OTDR module for access when the optical power of the optical fibers to be detected is abnormal in a preset period, and traversing all the optical fibers to be detected to obtain OTDR curves of all the optical fibers to be detected;
when the abnormality of the OTDR curve is monitored, switching to the optical power module, and sending the fiber core number and the abnormal event distance corresponding to the abnormal OTDR curve to the upper computer.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116953859A (en) * | 2023-09-18 | 2023-10-27 | 广东连捷精密技术有限公司 | Multi-channel high-speed optical port connector and optical connection method |
| CN117240349A (en) * | 2023-11-10 | 2023-12-15 | 北京中昱光通科技有限公司 | Double-main-path optical fiber automatic switching protection method and system based on online OTDR monitoring |
| CN117527058A (en) * | 2024-01-04 | 2024-02-06 | 深圳市飞思卓科技有限公司 | Optical fiber communication equipment monitoring method and system based on big data |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116953859A (en) * | 2023-09-18 | 2023-10-27 | 广东连捷精密技术有限公司 | Multi-channel high-speed optical port connector and optical connection method |
| CN117240349A (en) * | 2023-11-10 | 2023-12-15 | 北京中昱光通科技有限公司 | Double-main-path optical fiber automatic switching protection method and system based on online OTDR monitoring |
| CN117240349B (en) * | 2023-11-10 | 2024-02-06 | 北京中昱光通科技有限公司 | Double-main-path optical fiber automatic switching protection method and system based on online OTDR monitoring |
| CN117527058A (en) * | 2024-01-04 | 2024-02-06 | 深圳市飞思卓科技有限公司 | Optical fiber communication equipment monitoring method and system based on big data |
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