METHOD, APPARATUS AND SYSTEM FOR FAULT LOCATION

Abstract

This application relates to the field of fiber optic communication technologies, and provides a method, apparatus, and fault location system.The method includes: obtaining a first correspondence between a receive time and a receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component disposed in each port of at least one stage of the optical splitter is in downlink transmission in an ODN, where the reverse path includes backscatter and reflection or includes backscatter; determining, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port; and locating a fault in the ODN based on the second correspondence.

Description

METHOD, APPARATUS AND SYSTEM FOR FAULT LOCATION TECHNICAL FIELD This application relates to the field of fiber optic communication, and in particular to a fault location method, apparatus and system. BACKGROUND OF THE INVENTION A passive optical network system includes an optical line terminal (OLT), an optical distribution network (ODN), and multiple optical access network user terminals. The optical access network user terminals are either optical network units (ONUs) or optical network terminals (ONTs). The ODN can be divided into an optical splitter, a feeder fiber, a distribution fiber (which consists of multiple stages of optical splitters), and a downlink fiber. The feeder fiber connects the OLT to the ODN, the distribution fiber connects the optical splitters in multiple stages, and the downlink fiber connects the optical splitter to the optical access network user terminal.An explosive increase in the number of passive optical network systems being built leads to a shortage of maintenance engineers, a heavy workload, a lack of maintenance resources, and difficulty in accurately locating faults. The difficulty in locating faults is most pronounced in the optical network (ODN), primarily due to the large number of ODNs. As a result, the network is complex, making it relatively difficult to quickly pinpoint a fault. In a related technology, an Optical Time Domain Reflectometer (OTDR) is deployed at one end of the central office (one side of the OLT). The OTDR emits an optical signal for downlink transmission. When the optical signal is transmitted over an optical fiber, a portion of the signal is reflected and backscattered, returning to the OTDR via the reverse path and being detected. The OTDR establishes a correlation between transmission distance and receive power by using the receive power of a received optical signal and the receive time of the optical signal.The receive power at a transmission distance is the superposition of the optical signals backscattered by all distribution and downstream optical fibers at the transmission distance in the ODN, or the superposition of the optical signals reflected and backscattered by all distribution and downstream optical fibers at the transmission distance (the optical fiber reflects the optical signal at a broken location within the fiber). Based on this mapping, the OTDR can determine a location where the receive power suddenly changes; and based on this location, it can determine if an optical fiber in the ODN has a fault. After the optical splitter is used, the receive power at a transmission distance is the superposition of the optical signals backscattered by all the distribution and downstream optical fibers at the transmission distance in the ODN, or the superposition of the optical signals reflected and backscattered by all the distribution and downstream optical fibers at the transmission distance. Therefore, even if a location is found where the receive power suddenly changes, a faulty distribution fiber and a faulty downstream optical fiber cannot be identified. BRIEF DESCRIPTION OF THE INVENTION The specifications of this application provide a method, apparatus, and system for fault location. This application can be used to accurately locate a fault in an ODN. According to the first aspect, a fault location method is provided and applied to a passive optical network. The passive optical network includes an optical distribution network (ODN), and a reflection component that reflects test optical signals of different wavelengths is provided at each port of at least one optical splitter stage in the ODN.The method includes: obtaining a first correspondence between a receive time and a receive power during the reverse path that occurs when an optical test signal that can be reflected by the reflection component disposed in each port of at least one stage of optical splitter is in downlink transmission in the ODN, where the reverse path includes backscatter and reflection or includes backscatter; determining, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port; and locating a fault in the ODN based on the second correspondence. In the solution shown in this application, a fault locator device can be an OTDR with an adjustable wavelength. When a fault is located on the ODN, a fault locator instruction can be sent to the OTDR (for example, an OLT sends the fault locator instruction). When the OTDR receives the fault locator instruction, it can sequentially send optical test signals of wavelengths that can be reflected by the reflection component at each port of at least one stage of the optical splitter, and record the transmission times. When an optical test signal of any wavelength within these wavelengths passes through the ODN, a reflection component at a port corresponding to the wavelength and at least one of these wavelengths will be reflected. The optical splitter stage in the ODN (Optical Distribution Frame) reflects (basically reflects completely) the wavelength test signal. However, the wavelength test signal is fully transmitted as it passes through another port in the ODN. It can be observed that the wavelength test signal is reflected and backscattered only by several optical fibers and a specific reflection component in the ODN (the optical fiber reflects the test signal when it breaks), so that a portion of the wavelength test signal returns to the OTDR (Optical Time-Distance Receiver) via the reverse path and is received by the OTDR. The OTDR can then record a correlation between a receive time and a receive power.In this way, a first correspondence is obtained between a reception time and a reception power during the reverse path that occurs when an optical test signal, which can be reflected by a reflection component corresponding to the wavelength, is being transmitted downlink in the ODN. Using each first correspondence, the OTDR can determine a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is being transmitted downlink in an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port. Based on each second correspondence, the OTDR can determine if a fault exists in the ODN and pinpoint the fault location.Thus, because an optical fiber between an optical splitter port and a component connected to the port corresponds to the second correspondence, it can be accurately determined, using the second correspondence, whether there is a fault in an optical fiber (a downstream optical fiber, a feeder optical fiber, and a distribution optical fiber) in the ODN, and a location where the fault occurs. In one possible embodiment, at least one stage of the optical splitter is a first-stage optical splitter. Determining, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when a test optical signal is in downlink transmission on an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port includes obtaining a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN;convert each first correspondence into a fourth correspondence between a transmission distance and the reception power during the reverse path and perform a subtraction between the reception power at the same transmission distance in the third correspondence and each fourth correspondence, to obtain a second correspondence between a transmission distance and the reception power during the reverse path that occurs when an optical test signal is transmitting from; QQQQ Ln / Zznz / E / YIAI downlink in an optical fiber between each port of the first stage optical splitter and a component connected to the port of the first stage optical splitter. In the solution shown in this application, the OTDR can obtain the third correspondence. In the third correspondence, the superimposed receive power corresponding to each transmission distance is the superposition of the power of the optical signals reflected and backscattered by all optical fibers at the transmission distance, or the superposition of the power of the optical signals backscattered by all optical fibers at the transmission distance.For a first correspondence between a receive time and a receive power during the reverse path that occurs when a test optical signal that can be reflected by a reflection component arranged in the first port of the first-stage optical splitter (the first port being any port of the first-stage optical splitter) is in downlink transmission in the ODN, the OTDR can determine, using a transmission time of the test optical signal and the receive time in the first correspondence, a transmission distance that corresponds to each receive time in the first correspondence. The OTDR then performs a correspondence between the transmission distance corresponding to each receive time and the receive power, to obtain a fourth correspondence between transmission distance and receive power.The OTDR can separately subtract the receive power at the same transmission distance in the third and fourth correspondences to obtain a receive power difference corresponding to each transmission distance in the fourth correspondence. The OTDR determines that a correspondence between transmission distance and receive power difference is a second correspondence between transmission distance and receive power during the reverse path, which occurs when a test optical signal is being transmitted downlink in an optical fiber between the first port and a component connected to the first port. In this way, the second correspondence can be accurately determined. In a possible implementation, at least one stage of the optical splitter includes a first-stage optical splitter and a second-stage optical splitter. Determining, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when a test optical signal is in downlink transmission on an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port includes obtaining a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; and determining, based on the third correspondence and a first correspondence between a receive time and a QQQQ ίη / 77P7 / E / YΙΛΙ receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the second-stage optical splitter is in downlink transmission in the ODN, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the second-stage optical splitter and a component connected to the port of the second-stage optical splitter and determine, based on each first correspondence and each second correspondence,a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the first-stage optical splitter and a component connected to the port of the first-stage optical splitter. In the solution shown in this application, the OTDR can obtain the third correspondence. In the third correspondence, the superimposed receive power corresponding to each transmission distance is the superposition of the power of the optical signals reflected and backscattered by all optical fibers at the transmission distance, or the superposition of the power of the optical signals backscattered by all optical fibers at the transmission distance. For a first correspondence between a receive time and a receive power during the reverse path that occurs when a test optical signal that can be reflected by a reflection component arranged in a second port of the second-stage optical splitter (the second port being any port of the second-stage optical splitter) is in downlink transmission in the ODN, the OTDR can determine, using a transmission time of the test optical signal and the receive time in the first correspondence, a transmission distance that corresponds to each receive time in the first correspondence. The OTDR then performs a correspondence between the transmission distance corresponding to each receive time and the receive power, to obtain a fourth correspondence between transmission distance and receive power.The OTDR can separately subtract the receive power at the same transmission distance in the third and fourth correspondences to obtain a receive power difference corresponding to each transmission distance in the fourth correspondence. The OTDR determines that a correspondence between transmission distance and receive power difference is a second correspondence between transmission distance and receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between the second port and a connected component. QQQQ Ln / Zznz / E / YIAI second port. The OTDR can determine, by using each first and second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of the second-stage optical splitter connected to a first port (the first port being any port of the first-stage optical splitter) and a component connected to the port of the second-stage optical splitter, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between the first port and a component connected to the first port. In this way, the second correspondence can be accurately determined. In a possible implementation, obtaining a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN includes obtaining a correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal of a first wavelength is in downlink transmission in the ODN, and determining the correspondence as the third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN, where the first wavelength is different from a wavelength of an optical test signal that can be reflected by the reflection component at each port of at least one stage of the optical splitter;or determine the third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN based on a first correspondence between a receive time and the receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the first-stage optical splitter is in downlink transmission in the ODN.; In the solution shown in this application, the OTDR can send the optical test signal of the first wavelength and record a transmission time for sending the optical test signal of the first wavelength. When the optical test signal of the first wavelength passes through the ODN, all the reflection components arranged in the ports of at least one stage of the optical splitter in the ODN transmit the optical test signal of the first wavelength, and only some optical fibers and optical splitters in the ODN reflect and backscatter or backscatter the optical test signal of the first wavelength, so that a portion of the optical test signal of the first wavelength returns to the OTDR and is received by the OTDR. The OTDR can record a correspondence between a reception time and a reception power, and then determine a distance of QQQQ ίη / ZZΖΠZ / E / YΙΛΙ transmission by using a difference between the reception time and a sending time, to obtain a correspondence between a transmission distance and the reception power, i.e., to obtain the third correspondence. Alternatively, after obtaining the first correspondence between a receive time and a receive power during the reverse path that occurs when the optical test signal that can be reflected by the reflection component arranged in each port of at least one stage of the optical splitter is in downlink transmission in the ODN, the OTDR can convert, into a correspondence between a transmission distance and a receive power, the first correspondence between a receive time and a receive power during the reverse path that occurs when the optical test signal that can be reflected by the reflection component arranged in each port of the first stage optical splitter is in downlink transmission in the ODN.After this, the OTDR sums the receive power at the same transmission distance for these correspondences to obtain a value, and then divides (m-1) by this value to obtain the receive power at the same transmission distance, where m is the number of ports on the first-stage optical splitter. In this way, the receive power at each transmission distance is determined, and a correspondence can be made between the transmission distance and the receive power to obtain the third correspondence. Thus, because it is not necessary to send the optical test signal at the first wavelength, the OTDR's wavelength adjustment range can be reduced. In a possible implementation, ODN fault location based on the second correspondence includes: if it is determined, based on a second correspondence between a transmission distance and the receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between a target port of at least one stage of the optical splitter and a component connected to the target port, that there is an abnormal location point where the receive power suddenly changes, determine the abnormal location point as a fault location point of the optical fiber between the target port and the component connected to the target port. In the solution shown in this application, the OTDR can detect, on every second match, whether there is an abnormal location point where the receive power suddenly changes. If an abnormal location point exists on the second match between a transmit distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission on the optical fiber between the target port of at least one stage of the optical splitter and the component connected to the target port, the abnormal location point can be QQQQ ίη / 77Ω7 / Β / YΙΛΙ can be determined as the optical fiber fault location point between the target port and the component connected to the target port. In this way, not only is a faulty optical fiber provided in the ODN, but also a location point where the optical fiber has faults. According to a second aspect, a fault location system is provided and applied to a passive optical network, where the system includes an optical time domain reflectometer (OTDR). The OTDR is configured to produce optical test signals of a plurality of wavelengths. The OTDR is also configured to perform the method according to the first aspect. According to a third aspect, a fault location system is provided and applied to a passive optical network, where the system includes an optical time domain reflectometer (OTDR) and an optical line terminal (OLT). The OTDR is configured to produce optical test signals of a plurality of wavelengths. The OTDR is also configured to detect the receive power and reception time of a received optical test signal. The OLT establishes a communication connection with the OTDR. The OLT is configured to perform the method according to the first aspect. According to a fourth aspect, a fault-locating apparatus is provided, where the apparatus includes a plurality of modules, and the plurality of modules execute instructions to implement the fault-locating method according to the first aspect. According to a fifth aspect, a fault-locating device is provided, where the fault-locating device includes a processor and a memory. Memory stores computer instructions. The processor executes the computer instructions to implement the method according to the first aspect. According to a sixth aspect, a computer-readable storage medium is provided, where the computer-readable storage medium stores computer instructions. When the computer instructions on the computer-readable storage medium are executed by a fault-locating device, the fault-locating device is enabled to perform the method according to the first aspect. According to a seventh aspect, the present application provides a computer program product, where the computer program product includes QQQQ Ln / Zznz / E / YIAI computer instructions. When the computer instructions are executed by a fault-locating device, the fault-locating device performs the fault-locating method according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic diagram of an application scenario according to an exemplary modality of this application. FIGURE 2 is a schematic diagram of an adjustable OTDR structure according to an exemplary modality of this application. FIGURE 3 is a schematic diagram of a fault-locating device structure according to an exemplary modality of this application. FIGURE 4 is a schematic diagram of a fault location method procedure according to an exemplary modality of this application. FIGURE 5 is a schematic diagram of an optical divider stage according to an exemplary modality of this application. FIGURE 6 is a schematic diagram of two stages of optical dividers according to an exemplary modality of this application. FIGURE 7 is a schematic diagram of a fault-locating apparatus structure according to an exemplary modality of this application. DETAILED DESCRIPTION OF THE MODALITIES To clarify the objectives, technical solutions, and advantages of this application, the following further describes in detail the implementations of this application with reference to the accompanying drawings. This application applies to a PON system. As shown in Figure 1, a PON system structure includes three parts: an OLT, an ODN, and an optical access network user terminal (such as an ONT). The ODN is typically divided into four parts: an optical splitter, a feed fiber, a distribution fiber, and a downstream fiber. The feed fiber is the optical fiber between the OLT and the ODN, the distribution fiber is the optical fiber between the multi-stage optical splitters, and the downstream fiber is the optical fiber between the optical splitter and the optical access network user terminal. Figure 1 is a diagram of a two-stage optical split ODN structure. A single-stage optical split ODN has only one feed fiber and one downstream fiber. Because the ODN includes a passive component, it is difficult to identify an optical fiber fault within the ODN. Therefore, this application provides a fault location method. To locate a fault in an ODN, a reflective component is used. QQQQ ίη / ZZΖΠZ / E / YΙΛΙ Optical test signals of different wavelengths are applied to each port of at least one stage of the optical splitter in the ODN. The reflectivity of the reflecting component at each port is greater than or equal to a preset value. Generally, the preset value is relatively large, for example, 99% or 98%. For example, at least one stage of the optical splitter includes a first-stage optical splitter, a Γ4 optical splitter, and a reflecting component that reflects the optical test signals of different wavelengths is applied to each of the four ports. The reflecting component can be a reflecting grid or another component. This is not limited in this modality of this application. Furthermore, the PON system also includes an OTDR, which is an adjustable OTDR. In this application, the adjustable OTDR is an OTDR with an adjustable wavelength. An adjustable OTDR means that, based on the original OTDR, it is enabled to send optical test signals of multiple wavelengths. These multiple wavelengths include the wavelength of an optical test signal that can be reflected by the reflection component located at each port of at least one stage of the optical splitter. The adjustable OTDR can also detect the receive power and reception time of a received optical test signal.The receiving power exists because the optical test signal is backscattered to the adjustable OTDR when transmitted through the optical fiber, and the optical test signal is reflected back to the adjustable OTDR when the optical fiber breaks, or because the reflecting component in the optical splitter port reflects the optical test signal back to the adjustable OTDR. When the fault location method is performed using the adjustable OTDR, the adjustable OTDR can also locate a fault. As shown in Figure 2, a schematic diagram of an adjustable OTDR is also provided. The adjustable OTDR includes a laser with an adjustable wavelength, an optical combiner / splitter (such as a coupler) or circulator, a receiving component, a processor, and similar components. The laser with an adjustable wavelength is configured to produce optical test signals of multiple wavelengths.The optical combiner / splitter or circulator is configured to send and receive an optical test signal. The receiving component is configured to detect the receive power, and the processor is configured to record a receive time, etc. Figure 2 shows only some of these components. It should be noted herein that, if there is both a service optical signal and a test optical signal, a component such as a wavelength division multiplexer configured to combine the service optical signal and the test optical signal may be placed between the adjustable OTDR and an ODN. In this case, the component is also used when the service optical signal is sent between an OLT and the ODN. The fault location method can be performed by a fault location device, which can be an OLT or an adjustable OTDR. Specifically, when performed by an OLT, the fault location method can be implemented by a board within the OLT. The fault location device itself can also be another device, such as a terminal or a server. As shown in Figure 3, the fault-finding device includes a memory 301 and a processor 302. Memory 301 can be read-only memory (ROM), a static storage device, a dynamic storage device, or similar. Memory 301 can store computer instructions. When the computer instructions stored in memory 301 are executed by processor 302, processor 302 is configured to perform the fault-finding method. The memory can also store data. Processor 302 can be a general-purpose central processing unit (CPU), an ASIC, a graphics processing unit (GPU), or any combination thereof. Processor 302 can include one or more chips. As shown in Figure 4, a procedure for performing a fault location method is provided. This procedure is described using an example where the fault location device is an OTDR with an adjustable wavelength. Step 401: Obtain a first correspondence between a receive time and a receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged at each port of at least one stage of the optical splitter is in downlink transmission in an ODN, where the reverse path includes backscatter and reflection or includes backscatter. Downlink transmission refers to transmission from an OLT to an ONT. The reverse path occurs when there is backscatter in an optical fiber, or when there is both backscatter and reflection in an optical fiber (for example, reflection occurs when an optical fiber is broken). Additionally, the reverse path also occurs when a reflective component reflects an optical test signal. In this mode, when a fault is located in the ODN, a fault location instruction can be sent to the OTDR (for example, the OLT sends the fault location instruction). When the OTDR receives the fault location instruction, it can sequentially send optical test signals at wavelengths that can be reflected by the reflection component at each port of at least one stage of the optical splitter, and record the transmission times of the optical test signals at these wavelengths. When an optical test signal of any wavelength within these wavelengths The QQQQ Ln / Zznz / E / YIAI wave passes through the ODN. A reflection component at one port, corresponding to the wavelength and belonging to at least one optical splitter stage in the ODN, reflects (basically fully reflects) the optical test signal of that wavelength. However, the optical test signal of that wavelength is fully transmitted as it passes through another port in the ODN. It can be learned that the optical test signal of that wavelength is reflected and backscattered only by several optical fibers and a specific reflection component in the ODN (generally, the optical fiber only backscatters the optical test signal, and the optical fiber also reflects the optical test signal when it breaks), so that a portion of the optical test signal of that wavelength returns to the OTDR via the reverse path and is received by the OTDR. The OTDR can record a correspondence between a receive time and a receive power.In this way, a first correspondence is obtained between a reception time and a reception power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component that corresponds to the wavelength is in downlink transmission in the ODN.Because it is necessary to send an optical test signal of a wavelength that can be reflected by the reflection component arranged in each port of at least one stage of the optical splitter, the first correspondence between a receive time and a receive power can be obtained during the reverse path that occurs when the optical test signal that can be reflected by the reflection component arranged in each port of at least one stage of the optical splitter is in downlink transmission in the ODN (for ease of description in the following, this description is simplified as a description that the first correspondence is obtained that corresponds to each port of at least one stage of the optical splitter). Step 402: Determine, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one optical splitter stage and a component connected to the port. In this mode, the OTDR can determine, using each first correspondence, the second correspondence between a transmission distance and the received power during the reverse path that occurs when a test optical signal is being transmitted downlink in the optical fiber between each port of at least one stage of the optical splitter and the component connected to the port. The reverse path occurs due to backscatter and reflection or backscatter. Thus, the received power generated by backscatter can alternatively be converted into an optical fiber loss; that is, the second correspondence can be a correspondence between the transmission distance (Ln / zznz / E / YiAi) and the optical fiber loss.The received power generated after backscattering and reflection can alternatively be converted into a transmission distance and a reflection event; that is, the second correspondence can alternatively be a correspondence between the transmission distance and the reflection event. If at least one stage of the optical splitter is an i-stage optical splitter (i is greater than or equal to 1), and the i-stage optical splitter is directly connected to the ONT, an optical fiber between each port of the i-stage optical splitter and a component connected to the port can be called a downstream optical fiber. If the optical splitter of at least one stage is an i-stage optical splitter, and the i-stage optical splitter is directly connected to an i-stage optical splitter, an optical fiber between each port of the i-stage optical splitter and the i-stage optical splitter connected to the port can be called a distribution optical fiber. In the present, for ease of description in the following, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port is described as a second correspondence that corresponds to an optical fiber connected to each port of at least one stage of the optical splitter. Step 403: Locate a fault in the ODN based on the second correspondence. In this mode, the OTDR can determine, based on the second correspondence determined in step 402, whether there is a fault in the ODN, and determine a fault location point. Then, the OTDR can notify the operations and maintenance engineer of the fault location point in the ODN, so that the operations and maintenance engineer knows the ODN fault information in time. In this way, a second correspondence between a transmission distance and a reception power can be directly obtained during the reverse path that occurs when a test optical signal is in downlink transmission on each optical fiber segment in the ODN, so that it can be accurately determined whether there is a fault in an optical fiber (a downlink optical fiber, a feeder optical fiber and a distribution optical fiber) in the ODN, and a location where the fault occurs can be accurately determined. In one possible embodiment, at least one stage of the optical splitter is a first-stage optical splitter. To be specific, the ODN includes only one optical splitter stage, or the ODN includes a plurality of optical splitter stages but a reflection component is QQQQ iP / 77Ω7 / B / YILI has only the first-stage optical splitter in each port. In stage 402, the processing to determine the second correspondence can be: to obtain a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; convert each first correspondence into a fourth correspondence between a transmission distance and the receive power during the reverse path and perform a subtraction between the receive power at the same transmission distance in the third correspondence and each fourth correspondence, to obtain a second correspondence between a transmission distance and the receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of the first stage optical splitter and a component connected to the port of the first stage optical splitter. In this mode, the OTDR can obtain the third correspondence. In the third correspondence, the superimposed receive power corresponding to each transmission distance is the superposition of the power of the optical signals reflected and backscattered by all optical fibers at the transmission distance, or the superposition of the power of the optical signals backscattered by all optical fibers at the transmission distance. For a first mapping corresponding to the first port of the first-stage optical splitter (the first port being any port of the first-stage optical splitter), the OTDR can determine, using the transmission time of a test optical signal obtained at the first mapping and the reception time at the first mapping, a transmission time corresponding to each reception time at the first mapping, and then determine a transmission distance using the transmission time. The OTDR then maps the transmission distance corresponding to each reception time to the reception power to obtain a fourth mapping between the transmission distance and the reception power.The OTDR can separately subtract the receive power at the same transmission distance in the third and fourth correspondences to obtain a receive power difference corresponding to each transmission distance in the fourth correspondence. The OTDR determines that a correspondence between transmission distance and receive power difference is a second correspondence between a transmission distance and a receive power during the reverse path, which occurs when an optical test signal is being transmitted downlink in an optical fiber between the first port and a component connected to the first port.Specifically, when each transmission time is converted into a transmission distance, the following formula can be used for the conversion: Transmission distance (D)=(c*t) / 2no, where c in the formula represents a speed of light, t represents a transmission time, i.e., a difference between a receive time and a send time, and no represents a refractive index of an optical fiber in the ODN. The above method can be used for processing for each port of the first stage optical splitter, to obtain the second correspondence between a transmission distance and the receive power during the reverse path that occurs when a test optical signal is in downlink transmission in the optical fiber between each port of the first stage optical splitter and the component connected to the port. For example, as shown in FIGURE 5, the ODN includes a first-stage optical splitter, and the first-stage optical splitter is a 1*3 optical splitter, and it connects to an ONT 1, an ONT 2, and an ONT 3. The reflection grids arranged at three ports (a port A, a port B, and a port C) of the first-stage optical splitter reflect the optical test signals 1, 2, and 3 respectively. The third correspondence is a correspondence between a transmission distance and a superimposed power for reflecting and backscattering any optical test signal by optical fibers between the ONT and port A, port B, and port C, or a correspondence between a transmission distance and a superimposed power for backscattering.When the optical test signal 1 is sent, the reflection grating at port A reflects most of the optical test signal 1, so the received power is the power superimposed on the reflection and backscatter of the optical test signal 1 by the optical fibers between the ONT and ports B and C, or the power superimposed on backscatter. When the optical test signal 2 is sent, the reflection grating at port B fully reflects the optical test signal 2, so the received power is the power superimposed on the reflection and backscatter of the optical test signal 2 by the optical fibers between the ONT and ports A and C, or the power superimposed on backscatter.When the optical test signal 3 is sent, the reflection grid at port C fully reflects the optical test signal 3, so the receive power is the power superimposed on the reflection and backscatter of the optical test signal 3 by the optical fibers between the ONT and ports A and B, or the power superimposed on backscatter. Therefore, the power superimposed on sending the optical test signal 1 can be subtracted from the receive power at the third correspondence to obtain the receive power generated when an optical fiber between port A and the ONT reflects and backscatters the optical test signal, or the receive power generated during backscatter.Similarly, the superimposed power for transmitting the optical test signal ^2 can be subtracted from the receive power at the third correspondence to obtain the receive power generated when an optical fiber between port B and the ONT reflects and backscatters the optical test signal, or the receive power generated during backscattering. The superimposed power for transmitting the optical test signal 3 can be subtracted from the receive power at the third correspondence to obtain the receive power generated when an optical fiber between port C and the ONT reflects and backscatters the optical test signal, or the receive power generated during backscattering. It should be noted herein that when the superimposed power is subtracted from the receive power at the third correspondence, the subtraction is performed between the receive power at the same transmission distance. It should be noted herein that, because the first-stage optical splitter connects directly to the ONT, the optical fiber connected to each port of the first-stage optical splitter is a downstream optical fiber. In one possible implementation, at least one stage of the optical splitter includes a first-stage and a second-stage optical splitter. Specifically, the ODN includes only two stages of optical splitters, or the ODN includes multiple stages of optical splitters, but a reflection component is provided at each port of only the first-stage and second-stage optical splitters. In stage 402, the processing to determine the second mapping can be: to obtain a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; to determine, based on the third correspondence and a first correspondence between a receive time and a receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged at each port of the second-stage optical splitter is in downlink transmission in the ODN; a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of the second-stage optical splitter and a component connected to the port of the second-stage optical splitter; and to determine, based on each first correspondence and each second correspondence,a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the optical splitter of, QQQQ ίη / 77Π7 / E / YΙΛΙ first stage and a component connected to the first stage optical splitter port. In this mode, the OTDR can obtain the third correspondence. In the third correspondence, the superimposed receive power corresponding to each transmission distance is the superposition of the power of the optical signals reflected and backscattered by all optical fibers at the transmission distance, or the superposition of the power of the optical signals backscattered by all optical fibers at the transmission distance. For a first mapping corresponding to a second port of the second-stage optical splitter (the second port being any port of the second-stage optical splitter), the OTDR can determine, using the transmission time of a test optical signal obtained at the first mapping and the reception time at the first mapping, a transmission distance corresponding to each reception time at the first mapping. The OTDR then performs a mapping between the transmission distance corresponding to each reception time and the reception power, to obtain a fourth mapping between transmission distance and reception power.The OTDR can separately subtract the receive power at the same transmission distance in the third and fourth correspondences to obtain a receive power difference corresponding to each transmission distance in the fourth correspondence. The OTDR determines that a correspondence between transmission distance and receive power difference is a second correspondence between transmission distance and receive power during the reverse path, which occurs when an optical test signal is being transmitted downlink on an optical fiber between the second port and a component connected to the second port.Specifically, when each transmission time is converted into a transmission distance, the following formula can be used for the conversion: Transmission distance (D)=(c*t) / 2n, where c in the formula represents a speed of light, t represents a transmission time, and n represents a refractive index of an optical fiber at the ODN. For the first port of the first-stage optical splitter (the first port being any port of the first-stage optical splitter), the OTDR can obtain a first mapping corresponding to each port of the first-stage optical splitter, and then convert, in terms of transmission distance and receive time, the first mapping corresponding to each port; that is, convert the first mapping into a mapping between transmission distance and receive power. The OTDR can separately obtain the second mappings corresponding to the optical fibers connected to all the ports of the second-stage optical splitter connected to the first port. QQQQ ίη / 77Π7 / E / YΙΛΙ The OTDR can determine, according to the following formula, the received power at a first transmission distance in a second correspondence that corresponds to an optical fiber connected to the first port: P=(1 / n)*[(P11 )-(n-1 )*(P0)]-(P21). In this formula, P11 is the sum of the receive power at the first transmission distance in the first correspondence corresponding to the ports other than the first port in the first stage optical splitter; P0 is the receive power at the first transmission distance in the first correspondence corresponding to the first port in the first stage optical splitter; P21 is the sum of the receive power at the first transmission distance in the second correspondences corresponding to the optical fibers connected separately to all the ports of the second stage optical splitter connected to the first port; yn is a number of ports other than the first port in the first stage optical splitter. In this way, the second correspondence corresponding to the optical fiber connected to the first port can be determined. This method can be used for each port of the first-stage optical splitter to obtain the second correspondences corresponding to the optical fibers connected to all ports. For example, as shown in FIGURE 6, the ODN includes a first-stage optical splitter and a second-stage optical splitter. The second-stage optical splitter connects to an ONT. The first-stage optical splitter is a 1x2 optical splitter. The second-stage optical splitter includes two 1x2 optical splitters. The reflecting grids on the two ports of the first-stage optical splitter reflect the 1 and 2 optical test signals, respectively. The optical fibers connected to these two ports are A and B, respectively. The reflecting grids on the ports of the two 1x2 optical splitters of the second-stage optical splitter reflect the 3, 4, 5, and 6 optical test signals, respectively. The optical fibers connected to these ports are C, D, E, and F, respectively. The OTDR can sequentially send the 1, 2, 3, 4, 5, and 6 optical test signals to obtain a first match for each port.The receive power in a first mapping corresponding to a port with a reflection component of 1 is the superposition of B, E, and F (i.e., B+E+F). Similarly, the receive power in a first mapping corresponding to a port with a reflection component of 2 is the superposition of A, C, and D (i.e., A+C+D). The receive power in a first mapping corresponding to a port with a reflection component of 3 is the superposition of A, B, and F. QQQQ ίη / ΖΖΠΖ / Ε / ΥΙΛΙ D, E, and F (i.e., A+B+D+E+F). The receive power in a first mapping corresponding to a port with a reflection component of 4 is the superposition of A, B, C, E, and F (i.e., A+B+C+E+F). The receive power in a first mapping corresponding to a port with a reflection component of 5 is the superposition of A, B, C, D, and F (i.e., A+B+C+D+F). The receive power in a first mapping corresponding to a port with a reflection component of 6 is the superposition of A, B, C, D, and E (i.e., A+B+C+D+E). Therefore, when a second mapping is determined, A, C, and D can be subtracted from A+C+D. When a second mapping is determined, B, E, and F can be subtracted from B+E+F. When a second correspondence corresponding to C is determined, A+B+D+E+F can be subtracted from A+B+C+D+E+F.When a second correspondence corresponding to D is determined, A+B+C+E+F can be subtracted from A+B+C+D+E+F. When a second correspondence corresponding to E is determined, A+B+C+D+F can be subtracted from A+B+C+D+E+F. When a second correspondence corresponding to F is determined, A+B+C+D+E can be subtracted from A+B+C+D+E+F. The second correspondence corresponding to the optical fiber connected to each ODN port can be obtained in this way. It should be noted herein that the subtraction of C and D from A+C+D is the subtraction of the receive power at the same transmission distance. Other cases are similar to this one, and the details are not described herein. The overlap of B, E, and F is the power of an optical test signal that is received by the OTDR after the three optical fiber segments B, E, and F backscatter separately or backscatter and reflect the optical test signal. In a possible implementation, the third correspondences that are found between a transmission distance and a reception power and that correspond to all the optical fibers of the ODN can be determined in the following two ways. Form 1: A correspondence is obtained between a transmission distance and a receive power during the reverse path that occurs when an optical test signal of a first wavelength is in downlink transmission in the ODN, and the correspondence is determined as a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN, where the first wavelength is different from a wavelength of an optical test signal that may be reflected by the reflection component at each port of at least one stage of the optical splitter. The first wavelength is different from the wavelength of a test optical signal that can be reflected by each port of at least one stage of the optical splitter. QQQQ Ln / Zznz / E / YIAI In this mode, when a fault is located in the ODN, a fault location instruction can be sent to the OTDR. Upon receiving the fault location instruction, the OTDR can send the optical test signal of the first wavelength and record a transmission time for sending the optical test signal of the first wavelength.When the first wavelength optical test signal passes through the ODN, all reflection components arranged at the ports of at least one stage of the optical splitter in the ODN transmit the first wavelength optical test signal, and only several optical fibers and optical splitters in the ODN reflect and backscatter or backscatter the first wavelength optical test signal (reflection occurs at a location of a broken optical fiber or reflection component), so that a portion of the first wavelength optical test signal returns to the OTDR and is received by the OTDR.The OTDR can record a correspondence between a receive time and a receive power, and then determine a transmission distance by using the difference between the receive time and the send time (the transmission distance can be determined directly using the formula above, and the details are not described herein), to obtain a correspondence between a transmission distance and a receive power, i.e., to obtain the third correspondence. Because none of the reflection components in the ODN reflect the first wavelength optical test signal, the first wavelength optical test signal can pass through all the optical fibers in the ODN.Therefore, the detected received power is the superimposed power obtained after all optical fibers backscatter the optical test signal of the first wavelength, or the superimposed power obtained after backscattering and reflection. It should be noted herein that the third match may be obtained first, and then the first match determined, or the first match may be determined first, and then the third match determined. This is not limited in this modality of this application. Form 2: A third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN is determined, based on a first correspondence between a receive time and the receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the first-stage optical splitter is in downlink transmission in the ODN. In this mode, after obtaining the initial mapping for each port of at least one stage of the optical splitter, the OTDR can convert this mapping into a mapping between a transmission distance and a receive power. Then, the QQQQ Ln / 77Ω7 / Β / YILI The OTDR sums the receive power at the same transmission distance across these correspondences to obtain a value, and then divides (m-1) by this value to obtain the receive power at the same transmission distance. In this way, the receive power at each transmission distance is determined, and a correspondence between transmission distance and receive power can be established to obtain the third correspondences between transmission distance and receive power, which correspond to all the optical fibers in the ODN. This allows for a reduction in the OTDR's wavelength adjustment range. In Form 2, m is the number of ports on the first-stage optical splitter. In a possible implementation, in stage 403, a fault in the ODN can be located as follows. If it is determined, based on a second correspondence between a transmission distance and the received power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between a first port of at least one stage of the optical splitter and a component connected to the first port, that there is an abnormal location point where the received power suddenly changes, the abnormal location point is determined to be a fault location point of the optical fiber between the first port and the component connected to the first port. In this mode, the OTDR can detect, in the second mapping corresponding to the optical fiber connected to each port of at least one stage of the optical splitter, whether there is an abnormal location point where the receive power suddenly changes. If an abnormal location point exists in a second mapping corresponding to an optical fiber connected to a target port, it is determined that the optical fiber connected to the target port has a fault in the ODN. The abnormal location point can then be identified as a fault location point for the optical fiber connected to the target port. Thus, not only is a faulty optical fiber in the ODN identified, but also a specific location point where the optical fiber has a fault. It should be noted that if an abnormal location exists where the received power suddenly changes, it can be determined based on the second correspondence for the following reason: Normally, when an optical test signal is transmitted over an optical fiber, the received power decreases as the transmission distance increases (this is described only for transmission over the optical fiber, and the received power also increases as the optical test signal is transmitted to the ONT). However, when the optical fiber splits or breaks, there is a relatively high reflectivity in the optical test signal, resulting in a relatively high received power. Therefore, a fault location can be determined. QQQQ ίη / 77Ω7 / Β / YΙΛΙ based on a location point where the received power suddenly changes. The above is described using an example where the OTDR is the fault locator. When the OLT is used as a fault locator, it can establish a communication connection with the OTDR and obtain the first correspondence from the OTDR and a send time corresponding to each receive time in that first correspondence. The OLT then performs further processing based on the first correspondence, and this further processing is the same as that performed by the OTDR. Further details are not described herein. It should be noted that in this application, all the power described is received power. Received power can, however, be converted into optical fiber loss to pinpoint a fault in the ODN. Specifically, a formula for converting between received power and optical fiber loss is: optical fiber loss=10*log (receive power / 1 mW), where mW represents milliwatt, and a unit of optical fiber loss is dB. In this application method, a correlation is established between transmission distance and received power during the reverse path, which occurs when a test optical signal is being transmitted downlink in each optical fiber of the ODN. This allows for the precise determination of whether the optical fiber has faults. Therefore, a fault can be located more accurately within the ODN. Figure 7 is a diagram of a fault-locating apparatus structure according to one embodiment of this application. The apparatus may be implemented wholly or partially using software, hardware, or a combination thereof. The apparatus is applied to a passive optical network. The passive optical network includes an optical distribution network (ODN), and a reflection component that reflects optical test signals of different wavelengths is provided at each port of at least one optical splitter stage in the ODN. The apparatus provided in this embodiment of this application may implement the procedure of Figure 4 in the embodiments of this application. The apparatus includes a acquisition module 710 and a determination module 720. The 710 acquisition module is configured to obtain an initial match between a receive time and receive power during the reverse path that occurs when an optical test signal, which can be reflected by the reflection component at each port of at least one stage of the optical splitter, is being transmitted downlink in the ODN, where the reverse path includes backscatter and reflection or includes backscatter. The 710 acquisition module can be specifically configured to implement an acquisition function at stage 401 and a hidden stage included in the QQQQ Ln / Zznz / E / YIAI stage 401. The 720 determination module is configured to: determine, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port; and locate a fault in the ODN based on the second correspondence. The 720 determination module can be specifically configured to implement determination functions in stages 402 and 403, and the hidden stages included within stages 402 and 403. In one possible embodiment, at least one stage of the optical splitter is a first-stage optical splitter. The 720 determination module is configured to: to obtain a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; convert each first correspondence into a fourth correspondence between a transmission distance and a reception power during the reverse path; and perform a subtraction between the reception power at the same transmission distance in the third correspondence and in each fourth correspondence, to obtain a second correspondence between a transmission distance and the reception power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of the first stage optical splitter and a component connected to the port of the first stage optical splitter. In a possible implementation, at least one stage of the optical splitter includes a first-stage optical splitter and a second-stage optical splitter. The 720 determination module is configured to: to obtain a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; to determine, based on the third correspondence and a first correspondence between a reception time and a reception power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component disposed in each port of the second-stage optical splitter is in downlink transmission in the ODN, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the second-stage optical splitter and a component connected to the port of the second-stage optical splitter; and QQQQ Ln / Zznz / E / YIAI determine, based on each first correspondence and each second correspondence, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of the first stage optical splitter and a component connected to the port of the first stage optical splitter. In a possible implementation, the determination module 720 is configured to: obtain a correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal of a first wavelength is in downlink transmission in the ODN, and determine the correspondence as a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN, where the first wavelength is different from a wavelength of an optical test signal that can be reflected by the reflection component at each port of at least one stage of the optical splitter;or determine a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN, based on a first correspondence between a receive time and the receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the first-stage optical splitter is in downlink transmission in the ODN.; In a possible implementation, the 720 determination module is configured to: If it is determined, based on a second correspondence between a transmission distance and the receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between a target port of at least one stage of optical splitter and a component connected to the target port, that there is an abnormal location point where the receive power suddenly changes, determine the abnormal location point as a fault location point of the optical fiber between the target port and the component connected to the target port. The division of modules into modalities in this application is just one example; it's simply a division into logical functions and may be a different division during actual implementation. Furthermore, the functional modules in the modalities of this application can be integrated into a processor, or each module can exist physically on its own, or two or more modules can be integrated into a single module. The integrated module can be implemented in hardware or as a software functional module. QQQQ ίη / ΖΖΠΖ / Ε / ΥΙΛΙ The above modalities may be implemented wholly or partially using software, hardware, firmware, or any combination thereof. When implemented using a software program, the above modalities may be implemented wholly or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed in the OLT, all or some of the procedures or functions are generated in accordance with the modalities of this application. The computer instructions may be stored on a computer-readable storage medium or transmitted from one computer-readable storage medium to another.A computer-readable storage medium can be any medium usable and accessible by the OLT or a data storage device, such as a server or data center, that integrates one or more usable media. The usable medium can be magnetic (such as a floppy disk, hard drive, or magnetic tape), optical (such as a digital video disc, DVD), or semiconductor (such as a solid-state drive).

Claims

26 NOVELTY OF THE INVENTION Having described the present invention as above, the following claims are considered novel and, therefore, are claimed as property: CLAIMS 1. A fault location method, applied to a passive optical network, characterized in that the passive optical network comprises an optical distribution network, ODN, a reflection component that reflects optical test signals of different wavelengths is disposed in each port of at least one optical splitter stage in the ODN, and the method comprises: obtaining a first correspondence between a reception time and a reception power during the reverse path that occurs when an optical test signal that can be reflected by the reflection component disposed in each port of at least one optical splitter stage is in downlink transmission in the ODN, wherein the reverse path comprises backscatter and reflection or comprises backscatter;to determine, based on the first correspondence, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one optical splitter stage and a component connected to the port; and to locate a fault in the ODN based on the second correspondence.

2. The method according to claim 1, characterized in that at least one optical splitter stage is a first-stage optical splitter; and determining, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission on an optical fiber between each port of at least one optical splitter stage and a component connected to the port comprises: obtaining a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; converting each first correspondence into a fourth correspondence between a transmission distance and a receive power during the reverse path;and perform a subtraction between the received power at the same transmission distance in the third correspondence and in each fourth correspondence, to obtain a second correspondence between a transmission distance and the received power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the first stage optical splitter and qqqq Ln / zznz / E / viAi a component connected to the port of the first stage optical splitter.; 3. The method according to claim 1, characterized in that at least one stage of the optical splitter comprises a first-stage optical splitter and a second-stage optical splitter; and determining, based on the first correspondence, a second correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port comprises: obtaining a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN;determine, based on the third correspondence and a first correspondence between a reception time and a reception power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the second-stage optical splitter is in downlink transmission in the ODN, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the second-stage optical splitter and a component connected to the port of the second-stage optical splitter;and to determine, based on each first correspondence and each second correspondence, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when a test optical signal is in downlink transmission in an optical fiber between each port of the first-stage optical splitter and a component connected to the port of the first-stage optical splitter.

4. The method according to claim 2 or 3, characterized in that obtaining a third correspondence between a transmission distance in the ODN and the superimposed receive power of all the optical fibers in the ODN comprises: obtaining a correspondence between a transmission distance and a receive power during the reverse path that occurs when an optical test signal of a first wavelength is in downlink transmission in the ODN, and determining the correspondence as the third correspondence between a transmission distance in the ODN and the superimposed receive power of all the optical fibers in the ODN, wherein the first wavelength is different from a wavelength of an optical test signal that can be reflected by the reflection component at each port of the ODN minus one stage of the optical splitter;or determine the third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN, based on a first correspondence between a receive time and the receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the first-stage optical splitter is in downlink transmission in the ODN.; 5. The method according to any of claims 1 to 4, characterized in that the location of a fault in the ODN based on the second correspondence comprises: if it is determined, based on a second correspondence between a transmission distance and the receive power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between a target port of at least one stage of optical splitter and a component connected to the target port, that there is an abnormal location point where the receive power suddenly changes, determining the abnormal location point as a fault location point of the optical fiber between the target port and the component connected to the target port.

6. A fault location system, applied to a passive optical network, characterized in that the system comprises an optical time-domain reflectometer, OTDR, and an optical line terminal, OLT, wherein the OTDR is configured to produce optical test signals of a plurality of wavelengths; the OTDR is further configured to detect the receive power and receive time of a received optical test signal; the OLT establishes a communication connection with the OTDR; and the OLT is configured to perform the method according to any one of claims 1 to 5.

7. A fault location apparatus, applied to a passive optical network, characterized in that the passive optical network comprises an optical distribution network, ODN, a reflection component that reflects optical test signals of different wavelengths is disposed in each port of at least one optical splitter stage in the ODN, and the apparatus comprises: a obtaining module, configured to obtain a first correspondence between a receive time and a receive power during the reverse path that occurs when an optical test signal that can be reflected by the reflection component disposed in each port of at least one optical splitter stage is in downlink transmission QQQQ Ln / Zznz / E / YIAI in the ODN, wherein the reverse path comprises backscatter and reflection or comprises backscatter;and a determination module, configured to: determine, based on the first correspondence, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of at least one stage of the optical splitter and a component connected to the port; and locate a fault in the ODN based on the second correspondence.

8. The apparatus according to claim 7, characterized in that at least one stage of the optical splitter is a first-stage optical splitter; and the determination module is configured to: obtain a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN; convert each first correspondence into a fourth correspondence between a transmission distance and a receive power during the reverse path;and perform a subtraction between the received power at the same transmission distance in the third correspondence and in each fourth correspondence, to obtain a second correspondence between a transmission distance and the received power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the first stage optical splitter and a component connected to the port of the first stage optical splitter.; 9. The apparatus according to claim 7, characterized in that at least one stage of the optical splitter comprises a first-stage optical splitter and a second-stage optical splitter; and the determination module is configured to: obtain a third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN;determine, based on the third correspondence and a first correspondence between a reception time and a reception power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the second-stage optical splitter is in downlink transmission in the ODN, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between each port of the second-stage optical splitter and a component connected to the port of the second-stage optical splitter;and QQQQ Ln / Zznz / E / YIAI determine, based on each first correspondence and each second correspondence, a second correspondence between a transmission distance and a reception power during the reverse path that occurs when a test optical signal is in downlink transmission on an optical fiber between each port of the first-stage optical splitter and a component connected to the port of the first-stage optical splitter.; 10. The apparatus according to claim 8 or 9, characterized in that the determination module is configured to: obtain a correspondence between a transmission distance and a reception power during the reverse path that occurs when an optical test signal of a first wavelength is in downlink transmission in the ODN, and determine the correspondence as the third correspondence between a transmission distance in the ODN and the superimposed reception power of all optical fibers in the ODN, wherein the first wavelength is different from a wavelength of an optical test signal that can be reflected by the reflection component at each port of at least one stage of the optical splitter;or determine the third correspondence between a transmission distance in the ODN and the superimposed receive power of all optical fibers in the ODN, based on a first correspondence between a receive time and the receive power during the reverse path that occurs when an optical test signal that can be reflected by a reflection component arranged in each port of the first-stage optical splitter is in downlink transmission in the ODN.; 11. The apparatus according to any of claims 7 to 10, characterized in that the determination module is configured to: if it is determined, based on a second correspondence between a transmission distance and the received power during the reverse path that occurs when an optical test signal is in downlink transmission in an optical fiber between a target port of at least one stage of optical splitter and a component connected to the target port, that there is an abnormal location point where the received power suddenly changes, determine the abnormal location point as a fault location point of the optical fiber between the target port and the component connected to the target port.

12. A fault-locating device, characterized in that the fault-locating device comprises a processor and a memory, wherein the memory stores computer instructions; and the processor executes the computer instructions to implement the method according to any one of claims 1 to 5. qqqq Ln / zznz / E / YiAi 13. A computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions; and when the computer instructions in the computer-readable storage medium are executed by a fault-locating device, the fault-locating device is enabled to perform the method according to any one of claims 1 to 5.

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