An OSNR detection method and system for resisting SOP interference

Abstract

The invention discloses a kind of OSNR detection method and system for resisting SOP scrambling, the signal of the transmitting end at optical monitoring host A is first converted into a linear polarization state by 0 degree polarization controller, then the signal is divided into two beams by the coupler with a splitting ratio of γ, one beam is measured using a power meter, and the original power is recorded, and the other beam enters OPGN optical cable and propagates NT time, and the signal collected by A end and the signal received by B end are first combined by polarization beam combiner at receiving end optical monitoring host B, and then the electrically controlled rotatable polarizer is traversed to the most ideal polarization angle and interference effect matched with the received signal, and minimum noise power is recorded, and the power recorded by the power and the transmitting end is used, and finally OSNR value is calculated. The method and system of the present invention can be not affected by SOP scrambling, and is applicable to electric power communication system OPGW cable carrying mode, and it is realized that transmission line OPGW performance is dynamically monitored from time to time and the monitoring of the optical signal of link node.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission line monitoring, and in particular to an OSNR detection method and system resistant to SOP interference. Background Art

[0002] With the continuous development of smart dynamic grid transmission, OPGW (Optical Fiber Composite Overhead Ground Wire), as the main fiber optic deployment solution in the power communication industry, combines the dual functions of ground wire and communication transmission, with the advantages of high reliability and low cost.

[0003] However, since OPGW is a fiber-optic composite overhead ground wire, it is typically installed on tall towers and is significantly affected by extreme weather conditions. Lightning strikes are a major cause of transmission line failures. When struck by lightning, a strong current flows through the OPGW. This powerful current generates an internal magnetic field in the direction of optical fiber transmission, creating a strong magneto-optical rotation effect that shifts the state of polarization (SOP). This makes monitoring the OSNR of the scrambled signal difficult and leads to significant monitoring errors, seriously threatening the reliable operation of transmission network signals, communication security, and performance verification.

[0004] To meet the management, maintenance, and operation requirements of future power communication networks, and to enable the network to adaptively adjust signal bandwidth, data rate, transmission wavelength, signal power, etc. according to time-varying channel conditions, it is necessary to monitor and estimate the adaptive parameters that affect network performance. Optical signal-to-noise ratio (OSNR), which is directly related to signal quality, is one of the important parameters that need to be monitored.

[0005] Therefore, there is an urgent need for a method to accurately monitor the OSNR (Optical Signal Noise Ratio) of the SOP deviation signal caused by lightning strikes in OPGW, so as to timely understand the signal performance of the transmission line. This is of great significance for the lightning protection design and maintenance of transmission lines, the rapid restoration of power supply to the grid, and the safe and reliable operation of the power system. Summary of the Invention

[0006] The present invention addresses the problem that after an OPGW is struck by lightning, the SOP changes, making it difficult to monitor the OSNR of the signal after the signal is deflected, and the monitoring error is large. The present invention provides an OSNR detection method and system that is resistant to SOP deflection. A coupler is used to separate polarized signals, and a polarizer is used to change its polarization state. At the receiving end, the pre-transmission and post-transmission signals are combined. An electrically controlled rotatable polarizer is used to find the optimal polarization angle, filter out all signals, and obtain the minimum noise power, thereby calculating the OSNR. This method enables real-time dynamic monitoring of the OPGW performance of transmission lines under extreme weather conditions, enabling optical layer monitoring of optical signals at link nodes.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for detecting OSNR with SOP interference resistance is proposed. According to the difference in the optical polarization state signals detected by the transmitting end optical monitoring host A and the receiving end optical monitoring host B of the OPGW optical cable system, the power P that does not pass through the OPGW optical cable is obtained by performing polarization processing and acquisition on the transmitting end and detecting, controlling and calculating the signal with the receiving end. total And the minimum noise power P after passing through the OPGW optical cable min , realize OSNR calculation on OPGW.

[0009] Furthermore, the above-mentioned SOP-scrambling-resistant OSNR detection method comprises the following steps:

[0010] S1, first convert the signal at the transmitting optical monitoring host A into a linear polarization signal through a 0-degree polarization controller;

[0011] S2, then the linear polarization signal is divided into two beams through a coupler with a splitting ratio of γ. One beam is connected to the optical power meter to collect the signal power information at the transmitting optical monitoring host A. The power measured by the optical power meter is recorded as P total , that is, the power that does not pass through the OPGW optical cable; the other beam enters the OPGN optical cable and reaches the receiving end optical monitoring host B after N symbol periods T to measure the noise power;

[0012] S3: The signal received by the receiving optical monitoring host B and the signal collected by the transmitting optical monitoring host A are combined by a 0-degree polarization beam combiner PBC.

[0013] S4, inputting the obtained combined beam signal into an electrically controlled rotatable polarizer, and traversing the electrically controlled rotatable polarizer to an optimal polarization angle and interference effect that matches the received signal;

[0014] S5. A spectrum detection unit is used to monitor and obtain a corresponding spectrum, and the spectrum information obtained through the monitoring is input into the control and operation module;

[0015] S6. The control module controls the signal so that the polarization angle of the electrically controlled polarizer traverses from 0 degrees to 180 degrees and records the corresponding spectrum information, and adjusts the rotatable polarizer to the most ideal polarization angle and the best interference effect before outputting the signal.

[0016] S7. Record the minimum noise power P min , use the following formula to calculate the OSNR value:

[0017]

[0018] Among them, Ptotal is the power recorded by the transmitting end.

[0019] Furthermore, the polarization signal at the transmitting optical monitoring host A in step S1 is represented by the Jones matrix:

[0020]

[0021] Where x(t) is the time domain representation of the optical signal, θ is the azimuth angle of the signal, and ε is the ellipticity of the signal.

[0022] Furthermore, the frequency domain representation of the linear polarization state signal in step S1 is:

[0023]

[0024] where F(ω) is the frequency domain representation of the optical signal.

[0025] Furthermore, in step S2, the signal received by the receiving optical monitoring host B is:

[0026]

[0027] Furthermore, the beam combining signal in step S3 is expressed as:

[0028]

[0029] On the other hand, the present invention also provides an OSNR detection system for resisting SOP scrambling, comprising the following modules to implement any of the above methods:

[0030] Transmitter signal acquisition and processing module: This module processes the signal at the transmitter, converting it to a linear polarization state through a 0-degree polarization controller. It then splits the signal into two beams through a coupler with a splitting ratio of γ. One beam is measured using optical power, while the other enters the OPGN optical cable transmission module.

[0031] OPGN optical cable transmission module: used to transmit the other signal beam output by the coupler to the receiving end after N symbol periods T, so as to measure the noise power;

[0032] Receiver signal acquisition and processing module: used to monitor spectrum information, control the electrically controlled rotatable polarizer to traverse to the most ideal polarization angle and interference effect that matches the received signal, and record the minimum noise power P at that frequency. min , calculate the OSNR value.

[0033] Furthermore, the receiving end signal acquisition and processing module includes:

[0034] A determination unit, configured to combine the signals from the transmitting and receiving ends and adjust the combined signals to an optimal polarization angle through the control unit;

[0035] Spectrum detection unit, used to monitor spectrum information and obtain minimum noise power at the optimal polarization angle;

[0036] A control unit, configured to control the electrically controlled rotatable polarizer to traverse to an optimal polarization angle and interference effect that matches a received signal;

[0037] Operation unit, used to calculate the recorded minimum noise power P min , calculate the OSNR value.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention provides an OSNR detection method and system resistant to SOP scrambling. The method comprises the following steps: first, converting a signal from a transmitting end at an optical monitoring host A into a linear polarization state through a 0-degree polarization controller; then, dividing the signal into two beams through a coupler with a splitting ratio of γ; measuring one beam using a power meter to record the original power; and transmitting the other beam into an OPGN optical cable for NT time. At a receiving end optical monitoring host B, the signal collected from end A and the signal received from end B are first combined through a polarization beam combiner; then, an electrically controlled rotatable polarizer is controlled to traverse to the most ideal polarization angle and interference effect matching the received signal; and finally, the minimum noise power is recorded. The minimum noise power and the power recorded at the transmitting end are used to calculate the OSNR value. The method is not affected by SOP scrambling, is applicable to an OPGW optical cable carrying mode of an electric power communication system, and can realize real-time dynamic monitoring of the OPGW performance of a transmission line and monitoring of optical signals of link nodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0041] Figure 1 A flow chart of a method for detecting OSNR with resistance to SOP scrambling provided by an embodiment of the present invention.

[0042] Figure 2 This is a diagram of the architecture of an OSNR detection system that is resistant to SOP scrambling provided by an embodiment of the present invention.

[0043] Figure 3 This is a functional module diagram of the OSNR detection system with SOP scrambling resistance provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention aims to provide an OSNR monitoring method for power transmission line OPGW that resists SOP scrambling. In the case of SOP changes under conditions where lightning strikes may occur, a method for monitoring OSNR using polarization interference is proposed to achieve real-time dynamic monitoring of power transmission line OPGW performance under extreme weather conditions, thereby enabling optical layer monitoring of optical signals of link nodes. The method solves the problem that the SOP of existing optical cables changes after being struck by lightning, resulting in difficulties in monitoring the OSNR of signals after scrambling and large monitoring errors, and can quickly and accurately obtain OSNR monitoring results.

[0045] In order to better understand the present technical solution, the method of the present invention is described in detail below with reference to the accompanying drawings.

[0046] The present invention provides an OSNR detection method for resisting SOP scrambling, comprising the following steps:

[0047] S1. Based on the optical polarization state signals detected by the optical monitoring host A (transmitting end) and the optical monitoring host B (receiving end) connected to the two ends of the OPGN optical cable, the polarization signal at the transmitting optical monitoring host A is represented by the Jones matrix:

[0048]

[0049] Where x(t) is the time domain representation of the optical signal, θ is the azimuth angle of the signal, and ε is the ellipticity of the signal.

[0050] First, the signal at the transmitting optical monitoring host A is converted into a linear polarization signal through a 0-degree polarization controller. At this time, the signal is concentrated in the x-axis direction, and the frequency domain of the signal is expressed as:

[0051]

[0052] where F(ω) is the frequency domain representation of the optical signal.

[0053] S2, then the linear polarization signal is divided into two beams through a coupler with a splitting ratio of γ. One beam is connected to the optical power meter to collect the signal power information at the transmitting optical monitoring host A. The power measured by the optical power meter is recorded as P total , that is, the power that does not pass through the OPGW optical cable; the other beam enters the OPGN optical cable and reaches the receiving end optical monitoring host B after N symbol periods T to measure the noise power;

[0054] At this time, the signal received by the receiving optical monitoring host B is:

[0055]

[0056] S3. The signal received by the receiving optical monitoring host B and the signal collected by the transmitting optical monitoring host A are combined by the 0-degree polarization beam combiner PBC. The combined signal is expressed as:

[0057]

[0058] S4, inputting the obtained combined beam signal into an electrically controlled rotatable polarizer, and traversing the electrically controlled rotatable polarizer to an optimal polarization angle and interference effect that matches the received signal;

[0059] S5. A spectrum detection unit is used to monitor and obtain a corresponding spectrum, and the spectrum information obtained through the monitoring is input into the control and operation module;

[0060] S6. The control module controls the signal so that the polarization angle of the electrically controlled polarizer traverses from 0 degrees to 180 degrees and records the corresponding spectrum information. The rotatable polarizer is adjusted to the most ideal polarization angle and the best interference effect before outputting the signal. At this time, the signal is completely filtered out, and only half of the noise power passing through the polarizer is obtained.

[0061] S7. Record the minimum noise power P min , use the following formula to calculate the OSNR value:

[0062]

[0063] Among them, P total is the power recorded by the transmitting end.

[0064] The above results demonstrate an OSNR calculation method that is resistant to SOP rotation. This method allows timely understanding of the signal performance of transmission lines, which is of great significance for the design and maintenance of lightning protection for transmission lines, rapid restoration of power supply to the grid, and ensuring the safe and reliable operation of power systems.

[0065] On the other hand, the present invention also provides an OSNR detection system for resisting SOP scrambling, comprising the following modules to implement any of the above methods:

[0066] Transmitter signal acquisition and processing module M1: This module processes the signal at the transmitter, converting it to a linear polarization state through a 0-degree polarization controller and then splitting the signal into two beams through a coupler with a splitting ratio of γ. One beam is measured using optical power, and the other enters the OPGN optical cable transmission module.

[0067] OPGN optical cable transmission module M2: used to transmit the other signal beam output by the coupler to the receiving end after N symbol periods T, so as to measure the noise power;

[0068] Receiver signal acquisition and processing module M3: used to monitor spectrum information, control the electrically controlled rotatable polarizer to traverse to the most ideal polarization angle and interference effect that matches the received signal, and record the minimum noise power P at that frequency. min , calculate the OSNR value.

[0069] The receiving end signal acquisition and processing module includes:

[0070] A determination unit, configured to combine the signals from the transmitting and receiving ends and adjust the combined signals to an optimal polarization angle through the control unit;

[0071] Spectrum detection unit, used to monitor spectrum information and obtain minimum noise power at the optimal polarization angle;

[0072] A control unit, configured to control the electrically controlled rotatable polarizer to traverse to an optimal polarization angle and interference effect that matches a received signal;

[0073] Operation unit, used to calculate the recorded minimum noise power P min , calculate the OSNR value.

[0074] Example

[0075] First, the signal at the optical monitoring host A is a 45-degree polarization signal, which is equivalent to a frequency domain signal F(ω) multiplied by a 45-degree rotation matrix. Its frequency domain representation is S(ω):

[0076]

[0077] Passing the signal through a 0-degree polarizer, the signal becomes:

[0078]

[0079] The signal passing through the polarization controller passes through a coupler with a splitting ratio of γ, splitting the signal into two beams. One beam is connected to an optical power meter to collect signal power information from the optical monitoring host. The power measured by the optical power meter is recorded as Ptotal. The other beam enters the OPGN optical cable and reaches the receiving end after N symbol periods T. At the same time, since the optical vibration plane of linearly polarized light is fixed and does not rotate, the main noise related to OSNR calculation due to damage in the optical fiber is spontaneous emission noise. The polarization state of this noise is consistent with natural light, and it vibrates in all directions simultaneously. It can be fitted as two mutually perpendicular light vectors. When passing through the polarizer at any angle, half of the optical power is transmitted. To reach end B, the received signal can be expressed as:

[0080]

[0081] The signal received at the optical monitoring host B and the signal collected at the optical monitoring host A are passed through a 0-degree polarization beam combiner PBC. The signals can be combined into:

[0082]

[0083] The signal is monitored by a spectrum detection unit to obtain the corresponding spectrum. Based on the monitored spectrum information, the optimal polarization state, interference effect and minimum power P can be selected when the rotatable polarizer traverses from 0 degrees to 180 degrees. min .

[0084] In order to achieve the most ideal interference effect and the signal is incident with 135-degree polarization, the control unit is used to adjust the electrically controlled rotatable polarizer to the optimal polarization angle of 135 degrees. The signal after polarization interference can be expressed as:

[0085]

[0086] The signal power spectrum output by the polarizer is:

[0087]

[0088] It can be seen that when cosωNT = 1, the signal is completely filtered out, and only half of the noise power passes through the polarizer, thus separating the noise and calculating the noise power. The total OSNR is calculated by measuring the minimum noise power at the monitored spectral information:

[0089]

[0090] The above results demonstrate an OSNR detection method and system that is resistant to SOP interference. This method allows timely monitoring of transmission line signal performance, which is of great significance for transmission line lightning protection design and maintenance, rapid grid power restoration, and ensuring safe and reliable operation of power systems.

[0091] Each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0092] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for detecting OSNR against SOP deflection, characterized in that: According to the difference in the optical polarization state signals monitored by the transmitting end optical monitoring host A and the receiving end optical monitoring host B of the OPGW optical cable system, the power P that does not pass through the OPGW optical cable is calculated by performing polarization processing and acquisition on the transmitting end and detecting, controlling and calculating the signal with the receiving end. total And the minimum noise power P after passing through the OPGW optical cable min , realizing OSNR calculation on OPGW; the method comprises the following steps: S1, first convert the signal at the transmitting optical monitoring host A into a linear polarization signal through a 0-degree polarization controller; S2, then the linear polarization signal is divided into two beams through a coupler with a splitting ratio of γ. One beam is connected to the optical power meter to collect the signal power information at the transmitting optical monitoring host A. The power measured by the optical power meter is recorded as P total , that is, the power that does not pass through the OPGW optical cable; the other beam enters the OPGN optical cable and reaches the receiving end optical monitoring host B after N symbol periods T to measure the noise power; S3: The signal received by the receiving optical monitoring host B and the signal collected by the transmitting optical monitoring host A are combined by a 0-degree polarization beam combiner PBC. S4, inputting the obtained combined beam signal into an electrically controlled rotatable polarizer, and traversing the electrically controlled rotatable polarizer to an optimal polarization angle and interference effect that matches the received signal; S5. A spectrum detection unit is used to monitor and obtain a corresponding spectrum, and the spectrum information obtained through the monitoring is input into the control and operation module; S6. The control module controls the signal so that the polarization angle of the electrically controlled polarizer traverses from 0 degrees to 180 degrees and records the corresponding spectrum information, and adjusts the rotatable polarizer to the most ideal polarization angle and the best interference effect before outputting the signal. S7. Record the minimum noise power P min , use the following formula to calculate the OSNR value: Among them, P total is the power recorded by the transmitting end.

2. the OSNR detection method of anti-SOP according to claim 1, is characterized in that, The polarization signal at the transmitting optical monitoring host A in step S1 is represented by the Jones matrix: Where x(t) is the time domain representation of the optical signal, θ is the azimuth angle of the signal, and ε is the ellipticity of the signal.

3. the OSNR detection method of anti-SOP according to claim 1, is characterized in that, The frequency domain representation of the linear polarization state signal in step S1 is: Where F(ω) is the frequency domain representation of the optical signal.

4. the OSNR detection method of anti-SOP according to claim 1, is characterized in that, The signal received by the receiving optical monitoring host B in step S2 is: Where F(ω) is the frequency domain representation of the optical signal.

5. the OSNR detection method of anti-SOP according to claim 1, is characterized in that, The beam combining signal in step S3 is expressed as: Where F(ω) is the frequency domain representation of the optical signal.

6. An OSNR detection system resistant to SOP deflection, characterized in that: The method comprises the following modules to implement any one of claims 1 to 5: Transmitter signal acquisition and processing module: This module processes the signal at the transmitter, converting it to a linear polarization state through a 0-degree polarization controller. It then splits the signal into two beams through a coupler with a splitting ratio of γ. One beam is measured using optical power, while the other enters the OPGN optical cable transmission module. OPGN optical cable transmission module: used to transmit the other signal beam output by the coupler to the receiving end after N symbol periods T, so as to measure the noise power; Receiver signal acquisition and processing module: used to monitor spectrum information, control the electrically controlled rotatable polarizer to traverse to the most ideal polarization angle and interference effect that matches the received signal, and record the minimum noise power P at that frequency. min , calculate the OSNR value.

7. the OSNR detection system of anti-SOP scrambling according to claim 6, is characterized in that, The receiving end signal acquisition and processing module includes: A determination unit, configured to combine the signals from the transmitting and receiving ends and adjust the combined signals to an optimal polarization angle through the control unit; Spectrum detection unit, used to monitor spectrum information and obtain minimum noise power at the optimal polarization angle; A control unit, configured to control the electrically controlled rotatable polarizer to traverse to an optimal polarization angle and interference effect that matches a received signal; Operation unit, used to calculate the recorded minimum noise power P min , calculate the OSNR value.

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