A passive optical network monitoring device and detection method

Abstract

This application relates to a passive optical network (PON) monitoring device and detection method, comprising: a light generation module for generating pulsed light with a pseudo-random sequence; a circulator that transmits the optical signal downlink to the optical fiber trunk and simultaneously sends the reflected uplink optical signal to a reflected light analysis module; a splitter that distributes the downlink optical signal to optical network units (ONUs) and simultaneously converges the uplink optical signal to the optical fiber trunk; and a reflected light analysis module for receiving the reflected light signal and analyzing the fault location based on the reflected light signal. This application generates pulsed light with a pseudo-random sequence through the light generation module. The pulsed light reaches each branch link via the circulator and splitter. Reflection points on each branch link reflect the pulsed light back to the reflected light analysis module, which then analyzes the fault location based on the reflected light signal. This invention can achieve high-precision resolution by controlling the pulsed light with a pseudo-random sequence, and can be used for fault detection in point-to-multipoint networks.

Description

Technical Field

[0001] This application relates to the field of optical fiber communication technology, specifically to a passive optical network monitoring device and detection method. Background Technology

[0002] Currently, Passive Optical Networks (PONs) are widely used in access networks due to their high bandwidth, long transmission distance, low cost, multi-service support, and ease of maintenance. With the large-scale construction of fiber-to-the-home (FTTH), the number of fiber optic cables laid is constantly increasing, coverage is expanding, and the volume of services carried is also increasing. Therefore, establishing a low-cost, high-capacity, and highly reliable PON is crucial. However, due to the complexity of the access environment and the characteristics of long-distance transmission, fault monitoring and location have always been one of the significant challenges in PONs.

[0003] Among related technologies, OTDR (Optical Time Domain Reflectometer) can provide detailed information about fiber length, loss, attenuation, connection points, breakpoints, and other potential problems, and has wide application value in many fields such as fiber optic link fault finding and location, as well as fiber optic cable construction and maintenance. Therefore, OTDR has become the main solution for PON monitoring.

[0004] However, OTDR-based fault monitoring methods are mainly applicable to point-to-point networks. For point-to-multipoint networks, such as PON, the backscattered signal measured by the OTDR includes all signals from different branch links, so the signal of one branch may be partially or completely masked by the signals of other branches.

[0005] Therefore, it is necessary to design a new passive optical network monitoring device to overcome the above problems. Summary of the Invention

[0006] This application provides a passive optical network monitoring device and detection method, which can solve the technical problem that the OTDR-based fault monitoring method in related technologies is mainly applicable to point-to-point networks and not to point-to-multipoint networks.

[0007] In a first aspect, embodiments of this application provide a passive optical network monitoring device, comprising: a light generation module for generating pulsed light with a pseudo-random sequence; a circulator connected to the light generation module; a splitter connected to the circulator via an optical fiber trunk; multiple optical network units connected to the splitter via branch links, each branch link having a reflection point; and a reflected light analysis module connected to the splitter, the reflected light analysis module being used to receive reflected light signals and analyze fault locations based on the reflected light signals.

[0008] In conjunction with the first aspect, in one embodiment, the light generation module includes: a light source for emitting continuous light; and a modulation module connected to the light source and the circulator, the modulation module being used to modulate the continuous light emitted by the light source into pulsed light with a pseudo-random sequence.

[0009] In conjunction with the first aspect, in one embodiment, the modulation module includes: an intensity modulator connected to the light source; an acousto-optic modulator connected to the intensity modulator and the circulator; and a pseudo-random sequence generator connected to the intensity modulator and the acousto-optic modulator, wherein the pseudo-random sequence generator is used to modulate a pseudo-random sequence onto continuous light through the intensity modulator, and to drive the acousto-optic modulator to modulate the continuous light with the pseudo-random sequence into pulsed light with the pseudo-random sequence.

[0010] In conjunction with the first aspect, in one embodiment, the passive optical network monitoring device further includes an amplifier, the amplifier being disposed between the intensity modulator and the acousto-optic modulator, and the intensity modulator being connected to the acousto-optic modulator through the amplifier.

[0011] In conjunction with the first aspect, in one embodiment, the reflected light analysis module includes: a photodetector connected to the circulator, the photodetector being used for photoelectric conversion; and a data processing module connected to the photodetector, the data processing module being used for analyzing fault location based on reflected light signals.

[0012] In conjunction with the first aspect, in one embodiment, the reflected light analysis module further includes an optical filter located between the circulator and the photodetector, and the photodetector is connected to the circulator through the optical filter.

[0013] In conjunction with the first aspect, in one embodiment, the reflected light analysis module further includes an analog-to-digital converter (ADC), which is located between the photodetector and the data processing module, and the data processing module is connected to the photodetector through the ADC, the ADC being used to capture the reflected light signal trajectory.

[0014] In conjunction with the first aspect, in one implementation, the positions of the reflection points on each of the branch links are different.

[0015] Secondly, embodiments of this application provide a passive optical network link detection method, which includes the following steps:

[0016] A pulsed light with a pseudo-random sequence is sent to the circulator, so that the pulsed light with the pseudo-random sequence enters each branch link through the circulator and the splitter. Each branch link is connected to an optical network unit, and each branch link is provided with a reflection point.

[0017] Receive the reflected light signal and analyze the fault location based on the reflected light signal.

[0018] In conjunction with the second aspect, in one implementation, the analysis of fault location based on reflected light signals includes:

[0019] The position and time delay of the correlation peak are obtained by performing correlation operations between the sequence of reflected light signals and the pseudo-random sequence;

[0020] The location of the fault can be determined by the position and time delay of the relevant peaks.

[0021] The beneficial effects of the technical solutions provided in this application include:

[0022] The light generation module can generate pulsed light with a pseudo-random sequence. The pulsed light can reach each branch link through a circulator and a splitter. The reflection points set on each branch link can reflect the pulsed light. The reflected light analysis module can analyze the fault location based on the reflected light signal. Both the pulsed light and the reflected light signal contain a pseudo-random sequence. By controlling the pseudo-random sequence, high-precision resolution can be achieved, which can be used for fault detection in point-to-multipoint networks. This solves the technical problem that the OTDR-based fault monitoring method in related technologies is mainly applicable to point-to-point networks and not to point-to-multipoint networks. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a passive optical network monitoring device provided in an embodiment of this application;

[0025] Figure 2 In the example, (1) is the optical signal modulated by the intensity modulator provided in this application embodiment, and (2) is the optical signal after passing through the amplifier and the acousto-optic modulator.

[0026] In the picture:

[0027] 1. Light generation module; 11. Light source; 12. Intensity modulator; 13. Acousto-optic modulator; 14. Pseudo-random sequence generator; 15. Amplifier;

[0028] 2. Circulator; 3. Fiber optic trunk; 4. Splitter;

[0029] 5. Branch link; 6. Optical network unit; 7. Reflection point;

[0030] 8. Reflected light analysis module; 81. Photodetector; 82. Data processing module; 83. Optical filter; 84. Analog-to-digital converter. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0032] This application provides a passive optical network monitoring device and detection method, which can solve the technical problem that OTDR-based fault monitoring methods in related technologies are mainly applicable to point-to-point networks and not to point-to-multipoint networks.

[0033] See Figure 1 As shown in the figure, a passive optical network monitoring device provided in this application embodiment may include: a light generation module 1, which is used to generate pulsed light with a pseudo-random sequence; a circulator 2, which is connected to the light generation module 1; a splitter 4, which is connected to the circulator 2 through an optical fiber trunk 3; a plurality of optical network units 6, which are connected to the splitter 4 through branch links 5, and each branch link 5 is provided with a reflection point 7; and a reflected light analysis module 8, which is connected to the splitter 4, and is used to receive reflected light signals and analyze the fault location based on the reflected light signals.

[0034] In this embodiment, the splitter 4 is a 1:N splitter 4, which is used to distribute the probe light (i.e., pulsed light with a pseudo-random sequence) to n branch links 5, and to combine the reflected light signals from the n branch links 5 into one channel; each branch link 5 is connected to an optical network unit 6 (ONU) at its end, and the position of the reflection point 7 on each branch link 5 is different. The fiber optic trunk 3 is used for transmitting optical signals, fiber to the home, and optical wireless access.

[0035] In this embodiment, the light generation module 1 generates pulsed light with a pseudo-random sequence. The pulsed light passes through the circulator 2 and the splitter 4 to reach each branch link 5. The reflection point 7 set on each branch link 5 can reflect the pulsed light. The reflected light signals from each branch link 5 are combined into one by the splitter 4 and then reach the reflected light analysis module 8 through the circulator 2. After receiving the reflected light signal, the reflected light analysis module 8 can analyze the fault location based on the reflected light signal. Both the pulsed light and the reflected light signal contain a pseudo-random sequence. By controlling the pseudo-random sequence, the transmission rate of the pulsed light can be controlled. The higher the transmission rate, the better the spatial resolution, and the higher the resolution accuracy, the less the reflected light signals from each branch link 5 will interfere with each other. Therefore, it can be used for fault detection in point-to-multipoint networks, solving the technical problem that the OTDR-based fault monitoring method in related technologies is mainly applicable to point-to-point networks and not to point-to-multipoint networks. At the same time, the deployment and implementation of the passive optical network monitoring device provided in this embodiment does not require changes to the original PON structure, has strong scalability, and low cost.

[0036] Further, in one embodiment, the light generation module 1 may include: a light source 11 for emitting continuous light; and a modulation module connected to the light source 11 and the circulator 2, the modulation module being used to modulate the continuous light emitted by the light source 11 into pulsed light with a pseudo-random sequence. In this embodiment, the light source 11 can emit continuous light, and the modulation module can modulate and cut the continuous light emitted by the light source 11. It can first modulate the pseudo-random sequence onto the continuous light, and then cut the continuous light with the pseudo-random sequence to form pulsed light with a pseudo-random sequence. This embodiment separates the light source 11 from the modulation module; the separate modulation module can better adjust the pseudo-random sequence and then modulate a suitable pseudo-random sequence onto the continuous light emitted by the light source 11.

[0037] Furthermore, in some alternative embodiments, see Figure 1As shown, the modulation module may include: an intensity modulator 12 connected to the light source 11; an acousto-optic modulator 13 connected to the intensity modulator 12 and the circulator 2; and a pseudo-random sequence generator 14 connected to the intensity modulator 12 and the acousto-optic modulator 13. The pseudo-random sequence generator 14 is used to modulate a pseudo-random sequence onto continuous light through the intensity modulator 12, and to drive the acousto-optic modulator 13 to modulate the continuous light with the pseudo-random sequence into pulsed light with the pseudo-random sequence. In this embodiment, the pseudo-random sequence generator 14 can generate a pseudo-random sequence, and simultaneously, the pseudo-random sequence generator 14 can modulate the pseudo-random sequence onto the continuous light emitted by the light source 11 through the intensity modulator 12. The continuous light modulated by the intensity modulator 12 is as follows: Figure 2 As shown in (1), the pseudo-random sequence generator 14 can also drive the acousto-optic modulator 13 to cut continuous light and modulate the continuous light with a pseudo-random sequence into pulse light with a pseudo-random sequence. In this embodiment, the acousto-optic modulator 13 acts as an optical switch. Compared with transmitting continuous light, the energy of the pulse light carrying the pseudo-random sequence is more concentrated, which can improve the signal-to-noise ratio of the reflected light signal.

[0038] Based on the above technical solutions, see [link to relevant documentation]. Figure 1 As shown, in some embodiments, the passive optical network monitoring device may further include an amplifier 15, which is disposed between the intensity modulator 12 and the acousto-optic modulator 13, and the intensity modulator 12 is connected to the acousto-optic modulator 13 through the amplifier 15. In this embodiment, the amplifier 15 is used to amplify the optical signal. Continuous light with a pseudo-random sequence is first amplified by the amplifier 15 to obtain... Figure 2 (2) The continuous light shown then enters the acousto-optic modulator 13, and the acousto-optic modulator 13 modulates the continuous light with a pseudo-random sequence into pulse light with a pseudo-random sequence.

[0039] Furthermore, in one embodiment, see... Figure 1As shown, the reflected light analysis module 8 may include: a photodetector 81 connected to the circulator 2, the photodetector 81 being used for photoelectric conversion; and a data processing module 82 connected to the photodetector 81, the data processing module 82 being used to analyze the fault location based on the reflected light signal. In this embodiment, the photodetector 81 can detect the reflected light signal, perform photoelectric conversion on the reflected light signal, and transmit it to the data processing module 82. After receiving the converted reflected light signal, the data processing module 82 can perform correlation calculations between the sequence of the reflected light signal and a pseudo-random sequence. Based on the correlation peak and time delay, the location of the reflection point can be determined, and the change in the intensity of the branch light can be determined based on the amplitude change of the correlation peak, thereby detecting the fault. Furthermore, using the data processing module 82 to determine whether the link is faulty offers fast response speed and simple operation.

[0040] In this embodiment, the pulsed light signals reflected from different reflection points all contain pseudo-random sequences. The data processing module 82 performs an autocorrelation operation between the pseudo-random sequences in the reflected light and the originally transmitted pseudo-random sequences. Since reflected signals with different time delays will exhibit different correlation peaks on the time axis, the round-trip time of the reflected signals can be calculated based on the delay of the correlation peaks, with a time precision equal to the duration of a single bit in the pseudo-random sequence. Correspondingly, the spatial resolution of the reflection points depends on the duration of a single bit in the sequence, as shown in the formula: Where c represents the propagation speed of light in the optical fiber, and t represents the duration of a unit bit in the PN code. Therefore, the higher the transmission rate, the shorter the duration t of the unit bit, and the better the spatial resolution D, thus achieving high-precision resolution. Since the distances from the reflection points of each branch link to the splitter are rarely exactly equal, at high resolution, all reflection points will be identified as independent reflection peaks, making it easy to distinguish and identify each branch. Therefore, different reflection points can be identified based on their distances, which can be used for fault detection in point-to-multipoint networks.

[0041] Furthermore, in one embodiment, the reflected light analysis module 8 may further include an optical filter 83, which is located between the circulator 2 and the photodetector 81, and the photodetector 81 is connected to the circulator 2 through the optical filter 83. In this embodiment, after the reflected light signal passes through the circulator 2, it first passes through the optical filter 83 before reaching the photodetector 81, and the optical filter 83 can filter the reflected light signal.

[0042] Furthermore, in some embodiments, the reflected light analysis module 8 may further include an analog-to-digital converter 84, which is located between the photodetector 81 and the data processing module 82. The data processing module 82 is connected to the photodetector 81 through the analog-to-digital converter 84. The analog-to-digital converter 84 is used to capture the trajectory of the reflected light signal. In this embodiment, the reflected light signal passing through the photodetector 81 is received by the analog-to-digital converter 84, digitally processed, and its trajectory captured before reaching the data processing module 82 for analysis.

[0043] This application also provides a passive optical network link detection method, which may include the following steps:

[0044] Step 1: Send a pulsed light with a pseudo-random sequence to the circulator 2, so that the pulsed light with the pseudo-random sequence passes through the circulator 2 and the splitter 4 and enters each branch link 5. Each branch link 5 is connected to an optical network unit 6, and each branch link 5 is provided with a reflection point 7.

[0045] Step 2: Receive the reflected light signal and analyze the fault location based on the reflected light signal.

[0046] In this embodiment, the light generation module 1 can generate pulsed light with a pseudo-random sequence. Connecting the light generation module 1 to the circulator 2, the light generation module 1 can send the pulsed light with the pseudo-random sequence to the circulator 2. The pulsed light arriving in the circulator 2 can be sent to the splitter 4 via the fiber optic trunk 3. After splitting, the pulsed light is divided into N paths and sent to each branch link 5. The reflection point 7 on each branch link 5 can reflect the pulsed light, forming a reflected light signal. The reflected light signal passes through the splitter 4 and the circulator 2 in sequence and is received by the reflected light analysis module 8. The reflected light analysis module 8 can analyze the fault location based on the reflected light signal. The light generation module 1 in this embodiment can be any of the light generation modules 1 provided in the above embodiments and implement the corresponding functions, which will not be elaborated further here. Similarly, the reflected light analysis module 8 can be any of the reflected light analysis modules 8 provided in the above embodiments and implement the corresponding functions, which will not be elaborated further here.

[0047] In step 1, at the transmitting end, the pseudo-random sequence generator 14 modulates the pseudo-random sequence onto the optical signal via the intensity modulator 12. After passing through the amplifier 15, the signal enters the acousto-optic modulator 13. The pseudo-random sequence generator 14 drives the acousto-optic modulator 13 to modulate the pulsed light, generating pulsed light with a pseudo-random sequence that enters the ODN network through the circulator 2. The pulsed light with the pseudo-random sequence is reflected back at the reflection points 7 of each branch link 5 and then returns to the receiving end via the circulator 2.

[0048] In step 2, at the receiving end, the reflected light signal passes through the optical filter 83 and is detected by the photodetector 81. After being received by the analog-to-digital converter 84, it undergoes digital signal processing and is then transmitted to the data processing module 82.

[0049] Furthermore, in one embodiment, the analysis of fault location based on reflected light signals may include:

[0050] Step 21: Perform correlation operation between the sequence of reflected light signals and the pseudo-random sequence to obtain the position and time delay of the correlation peak.

[0051] Step 22: Determine the fault location by analyzing the position and time delay of the relevant peaks. Steps 21 and 22 are both performed in the data processing module 82.

[0052] In this embodiment, pseudo-random sequences, due to their autocorrelation properties, are typically used to verify the correctness and integrity of signals. When we perform a correlation operation between the transmitted pseudo-random sequence and the received signal, even under low signal-to-noise ratio conditions, a significant peak in the correlation result can be observed by precisely matching the pseudo-random sequence. This property is used to identify pseudo-random sequences from noisy received signals and to accurately determine time delays and time intervals. Based on the good autocorrelation properties of pseudo-random sequences, a significant correlation peak is only formed when the received sequence is aligned with the transmitted sequence. Therefore, the round-trip time of the reflected signal can be measured based on the delay of the correlation peak, with a time accuracy of the duration of a unit bit in the pseudo-random sequence and a spatial resolution of D = ct / 2, where c represents the propagation speed of light in the optical fiber and t represents the duration of a unit bit in the PN code.

[0053] In this application, firstly, at the transmitting end, a pseudo-random sequence generator 14 modulates a pseudo-random sequence onto continuous light using an intensity modulator 12. After amplification by an amplifier 15, the signal light is cut by an acousto-optic modulator 13 to obtain pulsed light with a pseudo-random sequence. The cut pulsed light then enters the optical fiber trunk 3 through a circulator 2, is connected to each branch link 5 by a splitter 4, and finally to the ONU. The pulsed light is reflected at reflection points 7 on each branch link 5. Finally, at the receiving end, the reflected light signal is correlated with the transmitted sequence to detect the pseudo-random sequence from the noise. This embodiment distinguishes each branch by the different positions of the reflection points 7 on each branch link 5. The passive optical network monitoring device is simple, inexpensive, easily expandable, has a fast monitoring response speed, is easy to operate, and reduces maintenance costs.

[0054] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0055] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A passive optical network monitoring device, characterized by It includes: A light generation module (1) is used to generate pulsed light with a pseudo-random sequence; Circulator (2), the circulator (2) is connected to the light generation module (1); The splitter (4) is connected to the circulator (2) via an optical fiber trunk (3). Multiple optical network units (6) are connected to the splitter (4) via branch links (5), and each branch link (5) is provided with a reflection point (7); the positions of the reflection points (7) on each branch link (5) are different; And a reflected light analysis module (8), which is connected to the circulator (2), the reflected light analysis module (8) is used to receive reflected light signals and analyze the fault location based on the reflected light signals; The light generation module (1) includes: A light source (11) is used to emit continuous light; Intensity modulator (12), the intensity modulator (12) is connected to the light source (11); Acousto-optic modulator (13), the acousto-optic modulator (13) being connected to the intensity modulator (12) and the circulator (2); A pseudo-random sequence generator (14) is connected to the intensity modulator (12) and the acousto-optic modulator (13). The pseudo-random sequence generator (14) is used to modulate a pseudo-random sequence onto continuous light through the intensity modulator (12) and drive the acousto-optic modulator (13) to modulate the continuous light with the pseudo-random sequence into pulsed light with the pseudo-random sequence.

2. The passive optical network monitoring device as described in claim 1, characterized in that, The passive optical network monitoring device further includes an amplifier (15), which is located between the intensity modulator (12) and the acousto-optic modulator (13), and the intensity modulator (12) is connected to the acousto-optic modulator (13) through the amplifier (15).

3. The passive optical network monitoring device of claim 1, wherein, The reflected light analysis module (8) includes: A photodetector (81) is connected to the circulator (2) and is used for photoelectric conversion; A data processing module (82) is connected to the photodetector (81) and is used to analyze the fault location based on the reflected light signal.

4. The passive optical network monitoring device as described in claim 3, characterized in that, The reflected light analysis module (8) further includes an optical filter (83), which is located between the circulator (2) and the photodetector (81), and the photodetector (81) is connected to the circulator (2) through the optical filter (83).

5. The passive optical network monitoring device as described in claim 3 or 4, characterized in that, The reflected light analysis module (8) further includes an analog-to-digital converter (84), which is located between the photodetector (81) and the data processing module (82), and the data processing module (82) is connected to the photodetector (81) through the analog-to-digital converter (84).

6. A method of passive optical network link detection, the method comprising: It includes the following steps: Pulsed light with a pseudo-random sequence is sent to the circulator (2) through the light source (11), intensity modulator (12), pseudo-random sequence generator (14), and acousto-optic modulator (13). The pulsed light with the pseudo-random sequence passes through the circulator (2) and splitter (4) and enters each branch link (5). Each branch link (5) is connected to an optical network unit (6), and each branch link (5) is provided with a reflection point (7). The positions of the reflection points (7) on each branch link (5) are different. The intensity modulator (12) is connected to the light source (11), and the acousto-optic modulator (13) is connected to the intensity modulator (12) and the circulator (2). The pseudo-random sequence generator (14) is connected to the intensity modulator (12) and the acousto-optic modulator (13). Receive the reflected light signal and analyze the fault location based on the reflected light signal.

7. The passive optical network link detection method as described in claim 6, characterized in that, The fault location analysis based on reflected light signals includes: The position and time delay of the correlation peak are obtained by performing correlation operations between the sequence of reflected light signals and the pseudo-random sequence; The location of the fault can be determined by the position and time delay of the relevant peaks.

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