Optical fiber link testing method and apparatus, and optical fiber communication system

Abstract

An optical fiber link testing method and apparatus, and an optical fiber communication system, which belong to the technical field of optical communications. The method comprises: a transmitting device generating a first optical signal carrying a CW optical signal, and transmitting the first optical signal to a receiving device by means of an optical fiber link; the receiving device receiving a second optical signal by means of the optical fiber link, wherein the second optical signal comprises the first optical signal; and the receiving device determining a target spectrum on the basis of the second optical signal, and determining the transmission performance of the optical fiber link on the basis of the target spectrum. In the present application, the existing transmitting device and receiving device in an optical fiber communication system are used to test the transmission performance of an optical fiber link, such that the testing of the transmission performance of optical fiber links can be realized, without the need to deploy additional devices in the optical fiber links, thereby achieving simple hardware implementation and low testing cost.

Description

Fiber optic link detection methods and devices, fiber optic communication systems

[0001] This application claims priority to Chinese patent application filed on January 27, 2025, with application number 202510126690.3 and entitled "Method and Apparatus for Detecting Fiber Optic Links and Fiber Optic Communication System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical communication technology, and in particular to a method and apparatus for detecting optical fiber links and an optical fiber communication system. Background Technology

[0003] Fiber optic communication systems typically consist of transmitting equipment, receiving equipment, and fiber optic links. The transmitting and receiving equipment are connected via a fiber optic link. The transmitting equipment modulates the information to be transmitted onto an optical signal and then transmits this optical signal to the receiving equipment via the fiber optic link. The receiving equipment receives the optical signal via the fiber optic link and demodulates the information carried by the optical signal. Fiber optic link anomalies can cause multipath interference (MPI) noise, mode partition noise (MPN), etc., leading to a deterioration in the signal-to-noise ratio (SNR) of the optical signal received by the receiving equipment. Therefore, it is necessary to test the transmission performance of the fiber optic link.

[0004] Currently, optical time domain reflectometers (OTDRs) are commonly used to detect the transmission performance of fiber optic links. For example, an OTDR is deployed in a fiber optic link, controlling it to send an optical signal to the link and detect the reflected optical signal. The transmission performance of the fiber optic link is determined based on the reflected optical signal detected by the OTDR.

[0005] However, current methods for testing the transmission performance of fiber optic links require an additional OTDR, which makes the hardware implementation for testing the transmission performance of fiber optic links complex and the testing cost high. Summary of the Invention

[0006] This application provides a method and apparatus for detecting optical fiber links, and an optical fiber communication system. The technical solution of this application is as follows.

[0007] Firstly, a method for detecting an optical fiber link is provided, applied to a transmitting device. The method includes: generating a first optical signal carrying a continuous wave (CW) optical signal, which is used by a receiving device to detect the transmission performance of the optical fiber link; and transmitting the first optical signal to the receiving device through the optical fiber link. The CW optical signal is a continuous, stable, single-frequency signal that does not involve modulation. The amplitude and frequency of the CW optical signal are constant.

[0008] The technical solution provided in this application involves a transmitting device sending a first optical signal carrying a CW optical signal to a receiving device via an optical fiber link. This CW optical signal is used by the receiving device to detect the transmission performance of the optical fiber link. Therefore, this application utilizes existing transmitting and receiving devices in the optical fiber communication system to detect the transmission performance of the optical fiber link. It eliminates the need for deploying additional equipment such as an OTDR in the optical fiber link and for removing or plugging / unplugging optical fibers, thus enabling the detection of the optical fiber link's transmission performance. Consequently, the hardware implementation for detecting the transmission performance of the optical fiber link is simple, and the detection cost is low.

[0009] Optionally, the first optical signal is converted into a second optical signal after transmission via the optical fiber link. The second optical signal includes the first optical signal and a reflected optical signal. The reflected optical signal includes a CW (Constant Wound) reflected optical signal, which is the signal reflected from the first optical signal during transmission via the optical fiber link. The CW reflected optical signal is the signal reflected from the CW optical signal carried by the first optical signal during transmission via the optical fiber link. For example, the reflected optical signal is the optical signal obtained by multiple (e.g., an even number of) reflections between reflection points on the optical fiber link during transmission of the first optical signal. The CW reflected optical signal is the optical signal obtained by multiple (e.g., an even number of) reflections between reflection points on the optical fiber link during transmission of the CW optical signal carried by the first optical signal. Reflection points on the optical fiber link include abnormal points, the reflective end face of the transmitting device (e.g., the end face of the laser of the transmitting device), and may also include other reflection points. Abnormal points on the optical fiber link can be connectors with abnormal end faces such as dirt or looseness. The intensity of both the reflected optical signal and the CW reflected optical signal depends on the reflection intensity of the reflection points.

[0010] Optionally, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. Since the service optical signal is used to carry the service signal (or service information), and the service optical signal typically carries the CW optical signal naturally, when the first optical signal carries both the CW optical signal and the service signal (or service information), the first optical signal can be the service optical signal. It is understood that in this application, the first optical signal carrying the CW optical signal includes two cases. In the first case, the first optical signal only carries the CW optical signal (e.g., the first optical signal is a CW optical signal). In the second case, the first optical signal is a service optical signal, which carries both the CW optical signal and the service signal (or service information).

[0011] The technical solution provided in this application carries CW optical signals and service signals in the first optical signal, which can realize the transmission performance of the fiber optic link for in-path detection.

[0012] Optionally, the method provided in the first aspect is executed by a transmitting device, an optical module in the transmitting device, or an optical fiber card in the transmitting device.

[0013] Secondly, a method for detecting an optical fiber link is provided, applied to a receiving device. The method includes: receiving a second optical signal through the optical fiber link, the second optical signal including a first optical signal carrying a CW optical signal, the CW optical signal being used by the receiving device to detect the transmission performance of the optical fiber link; the first optical signal being an optical signal generated by a transmitting device; determining a target spectrum based on the second optical signal; and determining the transmission performance of the optical fiber link based on the target spectrum. The CW optical signal is a continuous, stable, single-frequency signal that does not involve modulation. The amplitude and frequency of the CW optical signal are constant.

[0014] The technical solution provided in this application involves a receiving device receiving a second optical signal, including a first optical signal, via an optical fiber link. The first optical signal carries a CW optical signal used to detect the transmission performance of the optical fiber link. The receiving device determines a target spectrum based on the second optical signal and then determines the transmission performance of the optical fiber link based on the target spectrum. Therefore, this application utilizes existing transmitting and receiving equipment in an optical fiber communication system to detect the transmission performance of an optical fiber link. It eliminates the need for deploying additional equipment such as an OTDR in the optical fiber link and for fiber optic cable plugging / unplugging, thus enabling the detection of the optical fiber link's transmission performance. Consequently, the hardware implementation for detecting the transmission performance of an optical fiber link is simple, and the detection cost is low.

[0015] Optionally, the second optical signal also includes a reflected optical signal, which includes a CW reflected optical signal. This reflected optical signal is a signal reflected during the transmission of the first optical signal through the optical fiber link. The CW reflected optical signal is a signal reflected during the transmission of the CW optical signal carried by the first optical signal through the optical fiber link. For example, the reflected optical signal is an optical signal obtained through multiple reflections between reflection points on the optical fiber link during the transmission of the first optical signal through the optical fiber link. The CW reflected optical signal is an optical signal obtained through multiple reflections between reflection points on the optical fiber link during the transmission of the CW optical signal carried by the first optical signal through the optical fiber link. Reflection points on the optical fiber link include abnormal points, the reflective end face of the transmitting device (e.g., the end face of the laser of the transmitting device), and may also include other reflection points. Abnormal points on the optical fiber link can be connectors with abnormal end faces such as dirt or looseness. The intensity of both the reflected optical signal and the CW reflected optical signal depends on the reflection intensity of the reflection points. Determining the target spectrum based on the second optical signal includes: determining the target spectrum of the CW reflected optical signal based on the second optical signal.

[0016] The technical solution provided in this application allows the receiving device to determine the target spectrum of the CW reflected optical signal based on the second optical signal. This facilitates the receiving device in determining the transmission performance of the optical fiber link based on the target spectrum of the CW reflected optical signal, thereby enabling the detection of the transmission performance of the optical fiber link.

[0017] Optionally, determining the transmission performance of the optical fiber link based on the target spectrum includes: determining whether the CW reflected light signal contains an abnormal signal based on the target spectrum; if the CW reflected light signal contains an abnormal signal, determining that the optical fiber link is abnormal.

[0018] Optionally, determining the transmission performance of the optical fiber link based on the target spectrum includes: determining the distance between the reflective end face of the transmitting device and at least one anomalous point on the optical fiber link based on the target spectrum; and determining the location of the at least one anomalous point based on the distance between the reflective end face of the transmitting device and the at least one anomalous point. This allows for the location of the at least one anomalous point on the optical fiber link.

[0019] Optionally, the target spectrum includes a first spectral curve, which is the spectral curve of a first anomalous signal. The first anomalous signal is a signal obtained by reflecting the CW optical signal carried by the first optical signal between the reflective end face of the transmitting device and the first anomalous point. The at least one anomalous point on the optical fiber link includes the first anomalous point, and the CW reflected optical signal includes the first anomalous signal. Determining the distance between the reflective end face of the transmitting device and at least one anomalous point on the optical fiber link based on the target spectrum includes: extracting the first spectral curve from the target spectrum; and determining the distance between the reflective end face of the transmitting device and the first anomalous point based on the frequency corresponding to the characteristic peak of the first spectral curve.

[0020] Optionally, the first abnormal signal is a resonant signal, and the first spectral curve includes multiple periodically distributed characteristic peaks. The receiving device can determine the distance between the reflecting end face of the transmitting device and the first abnormal point based on the frequency corresponding to any characteristic peak of the first spectral curve.

[0021] Optionally, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. Since the service optical signal is used to carry the service signal (or service information), and the service optical signal typically carries the CW optical signal naturally, when the first optical signal carries both the CW optical signal and the service signal (or service information), the first optical signal can be the service optical signal. It is understood that in this application, the first optical signal carrying the CW optical signal includes two cases. In the first case, the first optical signal only carries the CW optical signal (e.g., the first optical signal is a CW optical signal). In the second case, the first optical signal is a service optical signal, which carries both the CW optical signal and the service signal (or service information).

[0022] The technical solution provided in this application carries CW optical signals and service signals in the first optical signal, which can realize the transmission performance of the fiber optic link for in-path detection.

[0023] In this application, the target spectrum of the CW reflected light signal can be determined by a single Fourier transform or by two Fourier transforms. Determining the target spectrum of the CW reflected light signal by two Fourier transforms makes the characteristic peaks of the spectral curve more prominent, thus facilitating the identification of the frequencies corresponding to these characteristic peaks for anomaly localization. The Fourier transform can be a Fast Fourier Transform (FFT), thereby reducing the computational complexity of determining the target spectrum of the CW reflected light signal.

[0024] Optionally, determining the target spectrum of the CW reflected light signal based on the second light signal includes the following seven implementation methods.

[0025] The first implementation method, which determines the target spectrum of the CW reflected optical signal based on the second optical signal, includes: converting the second optical signal into a baseband signal; and performing a Fourier transform on the baseband signal to obtain the target spectrum of the CW reflected optical signal. For example, this first implementation method is used to determine the target spectrum of the CW reflected optical signal when the first optical signal only carries the CW optical signal, such as when the first optical signal is a CW optical signal.

[0026] In the second implementation, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. For example, the first optical signal is a service optical signal, carrying both a CW optical signal and a service signal (or service information). Determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: converting the second optical signal into a baseband signal; filtering the baseband signal to obtain a filtered signal; and performing a Fourier transform on the filtered signal to obtain the target spectrum of the CW reflected optical signal.

[0027] In the third implementation, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. For example, the first optical signal is a service optical signal carrying both a CW optical signal and a service signal (or service information). Determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: converting the second optical signal into a baseband signal; performing a Fourier transform on the baseband signal to obtain a first spectrum; and filtering the first spectrum to obtain the target spectrum of the CW reflected optical signal.

[0028] The fourth implementation method, which determines the target spectrum of the CW reflected optical signal based on the second optical signal, includes: converting the second optical signal into a baseband signal; performing a Fourier transform on the baseband signal to obtain a first spectrum; and performing a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected optical signal. For example, this fourth implementation method is used to determine the target spectrum of the CW reflected optical signal when the first optical signal only carries a CW optical signal, such as when the first optical signal is a CW optical signal.

[0029] In the fifth implementation, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. For example, the first optical signal is a service optical signal, carrying both a CW optical signal and a service signal (or service information). Determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: converting the second optical signal into a baseband signal; filtering the baseband signal to obtain a filtered signal; performing a Fourier transform on the filtered signal to obtain a first spectrum; and performing a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected optical signal.

[0030] In the sixth implementation, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. For example, the first optical signal is a service optical signal, carrying both a CW optical signal and a service signal (or service information). Determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: converting the second optical signal into a baseband signal; performing a Fourier transform on the baseband signal to obtain a first spectrum; performing a Fourier transform on the first spectrum to obtain a second spectrum; and filtering the second spectrum to obtain the target spectrum of the CW reflected optical signal.

[0031] In the seventh implementation, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries both a CW optical signal and a service signal. For example, the first optical signal is a service optical signal carrying both a CW optical signal and a service signal (or service information). Determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: converting the second optical signal into a baseband signal; performing a Fourier transform on the baseband signal to obtain a first spectrum; filtering the first spectrum to obtain a second spectrum; and performing a Fourier transform on the second spectrum to obtain the target spectrum of the CW reflected optical signal.

[0032] The first to third implementations described above determine the target spectrum of the CW reflected optical signal through a single Fourier transform, while the fourth to seventh implementations determine the target spectrum of the CW reflected optical signal through two Fourier transforms. When the first optical signal carries only the CW optical signal, either the first or fourth implementation can be used to determine the target spectrum of the CW reflected optical signal.

[0033] Optionally, the target spectrum of the CW reflected light signal is determined by a first Fourier transform. The frequency corresponding to the characteristic peak of the first spectrum curve and the distance between the reflecting end face of the transmitting device and the first anomaly point satisfy: f N = c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflective end face of the transmitting device and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

[0034] Optionally, the target spectrum of the CW reflected light signal is determined by two Fourier transforms. The frequency corresponding to the characteristic peak of the first spectrum curve and the distance between the reflecting end face of the transmitting device and the first anomaly point satisfy: f N = 1 / c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflective end face of the transmitting device and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

[0035] Optionally, the method provided in the second aspect is executed by a receiving device, an optical module in the receiving device, or an optical fiber card in the receiving device.

[0036] Thirdly, a fiber optic link detection device is provided, applied to a transmitting device. The detection device includes at least one functional module for performing the method provided by the first aspect or any alternative method thereof. The at least one functional module can be implemented based on software, hardware, or a combination of both, and can be arbitrarily combined or divided based on a specific implementation. Optionally, the detection device is a transmitting device, an optical module within the transmitting device, or a fiber optic card within the transmitting device; alternatively, the detection device is integrated into the transmitting device, an optical module within the transmitting device, or a fiber optic card within the transmitting device.

[0037] Fourthly, a fiber optic link detection device is provided, applied to a receiving device. The detection device includes at least one functional module for performing the method provided in the second aspect or any alternative method described above. The at least one functional module can be implemented based on software, hardware, or a combination of both, and can be arbitrarily combined or divided based on a specific implementation. Optionally, the detection device is a receiving device, an optical module within the receiving device, or a fiber optic card within the receiving device; alternatively, the detection device is integrated into the receiving device, an optical module within the receiving device, or a fiber optic card within the receiving device.

[0038] Fifthly, a fiber optic link detection device is provided, comprising a memory and a processor; the memory is used to store a computer program; the processor is used to execute the computer program stored in the memory to cause the fiber optic link detection device to perform at least some steps of the method provided in the first aspect or any alternative method of the first aspect. Optionally, the detection device is a transmitting device, an optical module in the transmitting device, or a fiber optic card in the transmitting device, or the detection device is integrated into the transmitting device, the optical module in the transmitting device, or the fiber optic card in the transmitting device.

[0039] A sixth aspect provides a fiber optic link detection device, including a memory and a processor; the memory stores a computer program; the processor executes the computer program stored in the memory to cause the fiber optic link detection device to perform at least some steps of the method provided in the second aspect or any alternative method of the second aspect. Optionally, the detection device is a receiving device, an optical module in the receiving device, or a fiber optic card in the receiving device; or, the detection device is integrated into the receiving device, the optical module in the receiving device, or the fiber optic card in the receiving device.

[0040] In a seventh aspect, a detection device for an optical fiber link is provided, comprising a main control board and an interface board, the main control board and the interface board being used to implement the method provided as described in the first aspect or any alternative method of the first aspect.

[0041] Eighthly, a detection device for an optical fiber link is provided, comprising a main control board and an interface board, the main control board and the interface board being used to implement the method provided as described in the second aspect or any alternative method of the second aspect.

[0042] A ninth aspect provides an optical fiber link detection apparatus, including a processor and an optical device; the optical device is used to perform transmit / receive operations as provided in the first aspect or any alternative method of the first aspect; the processor is used to perform operations other than transmit / receive operations in the method provided in the first aspect or any alternative method of the first aspect.

[0043] In a tenth aspect, an apparatus for detecting an optical fiber link is provided, comprising a processor and an optical device; the optical device is used to perform transmit / receive operations as provided in the method of the second aspect or any alternative method thereof; the processor is used to perform operations other than transmit / receive operations in the method of the second aspect or any alternative method thereof.

[0044] Optionally, in the ninth and tenth aspects above, the processor includes an optical digital signal processor (ODSP); the optical device includes at least one of an optical transmitter or an optical receiver.

[0045] Optionally, in the ninth and tenth aspects mentioned above, the detection device is an optical module or a light card.

[0046] Eleventhly, an optical fiber communication system is provided, including a transmitting device, a receiving device, and an optical fiber link, wherein the transmitting device and the receiving device are connected via the optical fiber link. The transmitting device includes an optical fiber link detection device as provided in the third, fifth, seventh, or ninth aspects above; the receiving device includes an optical fiber link detection device as provided in the fourth, sixth, eighth, or tenth aspects above.

[0047] In a twelfth aspect, a computer-readable storage medium is provided, which stores a computer program that, when executed, implements at least some steps of the method provided by the first aspect or any alternative method of the first aspect, or implements at least some steps of the method provided by the second aspect or any alternative method of the second aspect.

[0048] In a thirteenth aspect, a computer program product is provided, comprising a program or code that, when executed, implements at least some steps of the method provided by the first aspect or any alternative method thereof, or implements at least some steps of the method provided by the second aspect or any alternative method thereof.

[0049] In a fourteenth aspect, a chip is provided, the chip including programmable logic circuitry and / or program instructions, the chip being configured to implement at least some steps of the method provided by the first aspect or any alternative method of the first aspect above, or to implement at least some steps of the method provided by the second aspect or any alternative method of the second aspect above.

[0050] The technical effects of the third to fourteenth aspects mentioned above can be referred to the technical effects of the first to second aspects, and will not be repeated here. Attached Figure Description

[0051] Figure 1 is a schematic diagram of an optical fiber communication system;

[0052] Figure 2 is a schematic diagram of an application scenario provided by an embodiment of this application;

[0053] Figure 3 is a flowchart of a fiber optic link detection method provided in an embodiment of this application;

[0054] Figure 4 is a schematic diagram of a first spectrum curve provided in an embodiment of this application;

[0055] Figure 5 is a schematic diagram of a fiber optic link detection method provided in an embodiment of this application;

[0056] Figure 6 is a schematic diagram of another fiber optic link detection method provided in an embodiment of this application;

[0057] Figure 7 is a schematic diagram of a fiber optic link detection device provided in an embodiment of this application;

[0058] Figure 8 is a schematic diagram of another fiber optic link detection device provided in an embodiment of this application;

[0059] Figure 9 is a schematic diagram of another fiber optic link detection device provided in an embodiment of this application;

[0060] Figure 10 is a schematic diagram of another fiber optic link detection device provided in an embodiment of this application. Detailed Implementation

[0061] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0062] An optical fiber communication system is a communication system that uses optical fiber as the transmission medium. By modulating information onto optical signals and transmitting them through optical fibers, an optical fiber communication system can achieve high-speed, long-distance, and high-capacity communication transmission.

[0063] Fiber optic communication systems typically include transmitting equipment, receiving equipment, and fiber optic links. The transmitting and receiving equipment are connected via a fiber optic link. The transmitting equipment modulates the information to be transmitted onto an optical signal and then transmits that optical signal to the receiving equipment via the fiber optic link. The receiving equipment receives the optical signal via the fiber optic link and demodulates the information carried by the optical signal.

[0064] Fiber optic link anomalies can induce multipath interference (MPI) noise, mode partition noise (MPN), and other issues, leading to a deterioration in the signal-to-noise ratio (SNR) of the received optical signal. Specifically, a fiber optic link typically consists of multiple fiber segments and multiple connectors, which connect the transmitting and receiving devices and the optical fibers. If the connector end face is dirty or loose, resulting in poor contact, the optical signal transmitted in the fiber optic link (referred to as the original optical signal for clarity) will experience significant reflection at the connector. The optical signals reflected back and forth between different connectors, and between the connector and the end face of the laser in the transmitting device (the laser end face of the transmitting device has strong reflectivity and can be considered a reflection point, also called the reflecting end face of the transmitting device), will be superimposed on the original optical signal, generating MPI noise that is related to the original optical signal but has a delay. The delay of MPI noise depends on the length of the fiber between the two reflection points that reflect the MPI noise (e.g., two connectors, or a connector and the reflective endface of the transmitting device). In multimode scenarios, reflections caused by reflection points such as connectors and the reflective endface of the transmitting device can also induce MPN. Both MPI noise and MPN can degrade the signal-to-noise ratio (SNR) of the received optical signal, affecting the transmission performance of the optical fiber communication system and even causing optical fiber link flashover (noise superimposed on the original optical signal, causing the receiving device to be unable to demodulate the service signal from the received optical signal for a short period of time). The SNR of the optical signal is also called the optical signal-to-noise ratio (OSNR). The transmitting and receiving devices are collectively referred to as communication devices. The terms "transmitting device" and "receiving device" are relative; any communication device in an optical fiber communication system can act as either a transmitting or receiving device.

[0065] For example, please refer to Figure 1, which shows a schematic diagram of an optical fiber communication system. This optical fiber communication system includes station 110 and station 120, which are connected by optical fiber link 130 and optical fiber link 140. Both station 110 and station 120 are communication devices. Optical fiber link 130 is a unidirectional link for communication between station 110 and station 120. Optical fiber link 130 includes multiple optical fiber segments 131 and multiple connectors 132 (two connectors 132 are shown in Figure 1), with adjacent optical fiber segments 131 connected by connectors 132. Optical fiber link 140 is a unidirectional link for communication between station 120 and station 110. Optical fiber link 140 includes multiple optical fiber segments 141 and multiple connectors 142 (two connectors 142 are shown in Figure 1), with adjacent optical fiber segments 141 connected by connectors 142. Station 110 modulates the information to be transmitted onto an optical signal and then transmits the optical signal (e.g., referred to as the original optical signal 1) to station 120 via fiber optic link 130. Station 120 receives the optical signal via fiber optic link 130 and demodulates the information carried by the optical signal. During the transmission of the original optical signal 1 in fiber optic link 130, if the end face of the connector 132 on fiber optic link 130 is dirty or the connector 132 is loose, resulting in poor contact, the original optical signal 1 will experience significant reflection at the connector 132. The optical signals reflected back and forth between different connectors 132, as well as the optical signals reflected back and forth between the connector 132 and the end face of the laser at station 110, will be superimposed on the original optical signal 1, generating MPI noise related to the original optical signal 1 but with a delay. In multimode scenarios, multiple reflections caused by reflection points such as connector 132 and the end face of the laser can also trigger MPN. Both MPI noise and MPN (Multi-Purpose Noise) can degrade the signal-to-noise ratio of the optical signal received by station 120, affecting the transmission performance of the optical fiber communication system and even causing intermittent interruptions in the optical fiber link 130. Similarly, station 120 modulates the information to be transmitted onto an optical signal and then sends the optical signal (e.g., referred to as the original optical signal 2) to station 110 via optical fiber link 140. Station 110 receives the optical signal via optical fiber link 140 and demodulates the information carried by the optical signal. During the transmission of the original optical signal 2 in optical fiber link 140, if the end face of the connector 142 on the optical fiber link 140 is dirty or the connector 142 is loose, resulting in poor contact, the original optical signal 2 will experience significant reflection at the connector 142. The optical signals reflected back and forth between different connectors 142, as well as the optical signals reflected back and forth between the connector 142 and the end face of the laser of station 120, will be superimposed on the original optical signal 2, generating MPI noise that is related to the original optical signal 2 but has a delay. In multimode scenarios, multiple reflections caused by reflection points such as connector 142 and the end face of the laser can also trigger MPN.Both MPI noise and MPN can degrade the signal-to-noise ratio of the optical signal received at site 110, affecting the transmission performance of the optical fiber communication system and even causing the optical fiber link 140 to disconnect intermittently.

[0066] Dirt on the connector end face or looseness are both considered fiber optic link anomalies, which can affect the transmission performance of the fiber optic transmission system. To prevent fiber optic link anomalies from impacting the transmission performance of the fiber optic communication system, it is necessary to monitor the transmission performance of the fiber optic link. For example, the transmission performance of the fiber optic link can be monitored when the transmission performance of the fiber optic communication system deteriorates, or, even when the transmission performance of the fiber optic communication system has not deteriorated, the transmission performance of the fiber optic link can be monitored periodically to provide early warning of potential problems.

[0067] Currently, optical time domain reflectometers (OTDRs) are commonly used to detect the transmission performance of fiber optic links. OTDRs detect the transmission performance of fiber optic links based on time-domain reflectometry, such as detecting loss, attenuation, reflection, and anomalies. For example, an OTDR is deployed in a fiber optic link, controlling it to transmit an optical signal through the link and detect the reflected optical signal. The transmission performance of the fiber optic link is determined based on the reflected optical signal detected by the OTDR. For instance, the presence of anomalies in the fiber optic link can be determined based on the time, intensity, and waveform of the reflected optical signal detected by the OTDR, and the location of anomaly points on the fiber optic link can be identified. Specifically, an OTDR consists of a laser and a detector, deployed at the same end of the fiber optic link. The laser is used to transmit an optical signal through the fiber optic link, and the detector is used to detect the reflected optical signal after the laser has transmitted the signal. In order for the reflected light signal to enter the detector, a circulator or power divider needs to be deployed on the fiber optic link, and the detector is connected to the fiber optic link through the circulator or power divider. The reflected light signal is coupled to the detector through the power divider or circulator so that the detector can detect the reflected light signal.

[0068] However, using OTDR to test the transmission performance of fiber optic links requires deploying hardware such as OTDRs and circulators (or power dividers) in the fiber optic link, and also requires fiber optic plugging and unplugging. This makes the hardware implementation for testing the transmission performance of fiber optic links complex and the testing cost high.

[0069] Currently, staff can also carry instruments to the site to perform anomaly detection on fiber optic links. However, common fiber optic links range in length from a few meters to tens of kilometers, and there are many connectors on these links, especially on longer links. Manual inspection requires manually checking each connector on the fiber optic link, which is cumbersome, complex, and has high labor costs.

[0070] This application provides a fiber optic link testing scheme that utilizes existing transmitting and receiving equipment in the fiber optic communication system to test the transmission performance of the fiber optic link. It eliminates the need for additional equipment such as OTDRs, circulators (or power dividers) within the fiber optic link, and avoids fiber optic plugging and unplugging. Therefore, the hardware implementation for testing the transmission performance of the fiber optic link is simple, the testing cost is low, and it enables in-line testing. Furthermore, it eliminates the need for personnel to carry instruments to the site for anomaly detection, resulting in low labor costs.

[0071] The technical solutions of the embodiments of this application are described below. First, the application scenarios of the embodiments of this application are introduced.

[0072] Please refer to Figure 2, which illustrates an application scenario provided by an embodiment of this application. This application scenario provides an optical fiber communication system. The optical fiber communication system includes a transmitting device 210, a receiving device 220, and an optical fiber link 230. The transmitting device 210 and the receiving device 220 are connected via the optical fiber link 230. The optical fiber link 230 includes multiple optical fiber segments 231 and multiple connectors 232, with adjacent optical fiber segments 231 connected via connectors 232. The optical fiber link 230 can be a bidirectional optical fiber link between the transmitting device 210 and the receiving device 220, or a unidirectional optical fiber link between them. That is, the optical fiber link 230 is used for the transmitting device 210 to transmit optical signals to the receiving device 220 and for the receiving device 220 to transmit optical signals to the transmitting device 210. Alternatively, the optical fiber link 230 is used for the transmitting device 210 to transmit optical signals to the receiving device 220, but not for the receiving device 220 to transmit optical signals to the transmitting device 210.

[0073] Transmitting device 210 and receiving device 220 are collectively referred to as communication devices. The communication device includes optical modules and / or optical fiber cards, which perform functions related to optical signal processing. Optionally, the optical modules and / or optical fiber cards are pluggable in the communication device. For example, the communication device includes slots into which the optical modules and / or optical fiber cards are inserted to be installed. In embodiments of this application, the communication device may be a network device, a terminal device, or a server. The network device may be an optical transport network device, a switch, or a router, etc. The terminal device may be a personal computer (PC), a desktop computer, a printer, or a camera, etc. For example, the optical modules are pluggable in the optical transport network device, switch, router, or terminal device, and the optical fiber cards are pluggable in the optical transport network device or data communication device.

[0074] The transmitting device 210 includes a network device, a terminal device, or a server, and the receiving device 220 includes a network device, a terminal device, or a server. The transmitting device 210 and the receiving device 220 can be the same type of communication device or different types of communication devices. In one example, both the transmitting device 210 and the receiving device 220 are network devices; for example, both are switches or both are routers. In another example, both the transmitting device 210 and the receiving device 220 are terminal devices; for example, both are PCs or both are desktop computers. In yet another example, both the transmitting device 210 and the receiving device 220 are servers. In yet another example, the transmitting device 210 is a network device, and the receiving device 220 is a terminal device or a server. In yet another example, the transmitting device 210 is a terminal device, and the receiving device 220 is a network device or a server. In yet another example, the transmitting device 210 is a server, and the receiving device 220 is a network device or a terminal device.

[0075] In this embodiment, the transmitting device 210 generates a first optical signal carrying a continuous wave (CW) optical signal and transmits it to the receiving device 220 via the optical fiber link 230. After transmission via the optical fiber link 230, the first optical signal becomes a second optical signal, which includes the first optical signal. The receiving device 220 receives the second optical signal via the optical fiber link 230, determines a target spectrum based on the second optical signal, and determines the transmission performance of the optical fiber link 230 based on the target spectrum. Therefore, in this embodiment, the transmitting device 210 and the receiving device 220 cooperate to detect the transmission performance of the optical fiber link 230. This eliminates the need for additional equipment such as OTDRs, circulators (or power dividers) in the optical fiber link 230, and eliminates the need for fiber optic plugging and unplugging. The hardware implementation for detecting the transmission performance of the optical fiber link 230 is simple, the detection cost is low, and in-line detection is possible. Furthermore, no on-site personnel are required to perform anomaly detection on the optical fiber link, resulting in low labor costs. CW optical signals are continuous, stable, and single-frequency signals that do not involve modulation. The amplitude and frequency of CW optical signals are constant.

[0076] It should be noted that the application scenario shown in Figure 2 is for illustrative purposes only and is not intended to limit the technical solution of this application. The structure of the optical fiber communication system can be adjusted according to actual needs. For example, the length of the optical fiber link 230 and the number of connectors 232 included in the optical fiber link 230 can be adjusted according to actual needs. In addition, the application scenario of this application embodiment may also include a control device or a network management device. The control device or network management device can be connected to the transmitting device 210 and the receiving device 220 respectively, and the control device or network management device can control the transmitting device 210 and the receiving device 220. For example, the control device or network management device controls the transmitting device 210 to generate a first optical signal carrying a CW optical signal; the control device or network management device controls the receiving device 220 to determine the target spectrum based on the received second optical signal, and determines the transmission performance of the optical fiber link 230 based on the target spectrum.

[0077] The above describes the application scenarios of the embodiments of this application. The method embodiments of this application are described below.

[0078] Please refer to Figure 3, which shows a flowchart of a fiber optic link detection method provided in an embodiment of this application. This detection method is performed by a transmitting device and a receiving device in a fiber optic communication system. For example, as shown in Figure 2, the anomaly detection method is performed by a transmitting device 210 and a receiving device 220. Referring to Figure 3, the detection method includes the following steps S301 to S305.

[0079] S301. The transmitting device generates a first optical signal, which carries a CW optical signal A. The CW optical signal A is used by the receiving device to detect the transmission performance of the optical fiber link Z.

[0080] For example, the transmitting device is transmitting device 210 in the optical fiber communication system shown in Figure 2, and the optical fiber link Z is optical fiber link 230.

[0081] CW optical signals are continuous, stable, and single-frequency signals that do not involve modulation. The amplitude and frequency of CW optical signals are constant.

[0082] In an optional embodiment, the first optical signal also carries a service signal (or service information). That is, the first optical signal carries the CW optical signal A and the service signal. Therefore, the embodiments of this application can achieve the transmission performance of the in-path detection fiber optic link Z.

[0083] It should be noted that, since the service optical signal is used to carry service signals (or service information), and service optical signals typically inherently carry CW optical signals, when the first optical signal carries both CW optical signal A and service signals (or service information), the first optical signal can be the service optical signal. It is understood that in the embodiments of this application, the first optical signal carrying CW optical signal A includes two cases. In the first case, the first optical signal only carries CW optical signal A; for example, the first optical signal is CW optical signal A. In the second case, the first optical signal is a service optical signal, carrying both CW optical signal A and service signals (or service information).

[0084] The transmitting device can generate the first optical signal using either direct modulation or external modulation. Direct modulation refers to modulation within the light source, specifically controlling the light source directly to emit the desired optical signal. Direct modulation is also called internal modulation. External modulation refers to using a modulator outside the light source to modulate the optical signal emitted by the light source. The light source can be a laser or a laser diode (LD). The laser can be a vertical cavity surface emitting laser (VCSEL), an electro-absorption modulated laser (EML), or a directly modulated laser (DML), etc. The modulator can be a Mach-Zehnder modulator (MZM) or an electrically variable optical attenuator (EVOA), etc. This application does not limit the light source or modulator.

[0085] In this embodiment of the application, the transmitting device may generate the first optical signal using any one of the following three implementation methods.

[0086] The first implementation involves a first optical signal carrying a CW optical signal A but not a service signal (or service information). The optical transmitter of the transmitting device includes a light source, and the transmitting device controls the light source to emit the first optical signal carrying the CW optical signal A. For example, the first optical signal is the CW optical signal A, and the transmitting device controls the light source to emit the CW optical signal A.

[0087] The second implementation involves a first optical signal carrying a CW optical signal A and a service signal (or service information). The transmitting device's optical transmitter includes a light source. The transmitting device uses the service signal to modulate the driving signal (e.g., driving current) of the light source, causing the light source to emit a first optical signal carrying the CW optical signal A and the service signal. For example, the first optical signal is a service optical signal, and the transmitting device uses the service signal (or service information) to modulate the driving signal (e.g., driving current) of the light source, causing the light source to emit a service optical signal carrying the CW optical signal A and the service signal (or service information).

[0088] The third implementation method: The first optical signal carries the CW optical signal A and the service signal (or service information). The optical transmitter of the transmitting device includes a light source and a modulator. The transmitting device controls the light source to emit the CW optical signal A. The transmitting device controls the modulator to modulate the CW optical signal A emitted by the light source with the service signal to obtain the first optical signal carrying the CW optical signal A and the service signal. The first optical signal is the service optical signal.

[0089] S302. The transmitting device sends the first optical signal to the receiving device through the optical fiber link Z.

[0090] For example, the receiving device is receiving device 220 in the optical fiber communication system shown in Figure 2, and the optical fiber link Z is optical fiber link 230.

[0091] The transmitting device includes an interface corresponding to the fiber optic link Z, through which it transmits a first optical signal to the receiving device. In a specific embodiment, the transmitting device includes an optical transmitter, which transmits the first optical signal to the receiving device through the interface.

[0092] The first optical signal is transmitted via fiber optic link Z and becomes a second optical signal, which includes the first optical signal. The second optical signal may also include a reflected optical signal R. The reflected optical signal R is the optical signal reflected during the transmission of the first optical signal via fiber optic link Z. For example, the reflected optical signal R is the optical signal that undergoes multiple (e.g., an even number of) reflections between reflection points on fiber optic link Z during the transmission of the first optical signal via fiber optic link Z. The intensity of the reflected optical signal R depends on the reflection intensity of the reflection points. Reflection points on fiber optic link Z include abnormal points on fiber optic link Z, the reflective end face of the transmitting device, and may also include other reflection points. Typically, dirt on the end face of the connector on fiber optic link Z, loose connectors, etc., can cause abnormalities; therefore, abnormal points on fiber optic link Z are usually the connectors on fiber optic link Z.

[0093] In this embodiment, the reflected optical signal R includes a CW reflected optical signal R1, which is a signal reflected during the transmission of the CW optical signal A carried by the first optical signal via the optical fiber link Z. For example, the CW reflected optical signal R1 is a signal obtained by multiple (e.g., an even number of) reflections between reflection points on the optical fiber link Z during the transmission of the CW optical signal A carried by the first optical signal via the optical fiber link Z. Any two reflection points on the optical fiber link Z can form a reflection cavity, and the reflection cavity formed by any two reflection points is the cavity formed between those two reflection points. The two reflection points forming any reflection cavity may include anomalies on the optical fiber link Z, and may also include the reflection end face of the transmitting device. The CW reflected optical signal R1 includes at least one CW sub-reflected optical signal, which corresponds one-to-one with at least one reflection cavity on the optical fiber link Z. Each CW sub-reflected optical signal is a signal obtained by reflecting the CW optical signal A within the corresponding reflection cavity (that is, a signal obtained by reflecting the CW optical signal A between the two reflection points forming the corresponding reflection cavity).

[0094] The CW optical signal A can resonate within some reflecting cavities on the optical fiber link Z. A reflecting cavity capable of resonating is called a resonant cavity, and the CW sub-reflected optical signal obtained by the reflection of the CW optical signal A within the resonant cavity can be called a resonant signal. The reflection points forming the resonant cavity include anomalous points on the optical fiber link Z and may also include the reflecting end face of the transmitting device. In an optional embodiment, the at least one CW sub-reflected optical signal includes at least one resonant signal, and the at least one reflecting cavity includes at least one resonant cavity. Each of the at least one resonant signal corresponds one-to-one with the at least one resonant cavity, and each resonant signal is the signal obtained by the reflection of the CW optical signal A within the corresponding resonant cavity (that is, the signal obtained by the reflection of the CW optical signal A between the two reflection points forming the corresponding resonant cavity).

[0095] Some resonant cavities on the optical fiber link Z are formed by the reflective endface of the transmitting device and anomalies on the optical fiber link Z. For ease of description, the resonant cavity formed by the reflective endface of the transmitting device and anomalies on the optical fiber link Z is called the target resonant cavity, and the resonant signal obtained by reflecting the CW optical signal A within the target resonant cavity is called the target resonant signal. In an optional embodiment, the at least one resonant signal includes at least one target resonant signal, and the at least one resonant cavity includes at least one target resonant cavity. The at least one target resonant signal corresponds one-to-one with the at least one target resonant cavity, and each target resonant signal is the signal obtained by reflecting the CW optical signal A within the corresponding target resonant cavity (that is, the signal obtained by reflecting the CW optical signal A between the two reflection points forming the corresponding target resonant cavity).

[0096] Based on the above description, it is easy to understand that in this embodiment, the CW reflected optical signal R1 includes at least one CW sub-reflected optical signal, which includes at least one resonant signal, and the at least one resonant signal includes at least one target resonant signal. The optical fiber link Z includes at least one reflecting cavity, which includes at least one resonant cavity, and the at least one resonant cavity includes at least one target resonant cavity. That is, all or part of the at least one CW sub-reflected optical signal is a resonant signal, and all or part of the at least one resonant signal is a target resonant signal. All or part of the at least one reflecting cavity is a resonant cavity, and all or part of the at least one resonant cavity is a target resonant cavity.

[0097] Based on the foregoing description, it is easy to understand that in the embodiments of this application, the first optical signal carries the CW optical signal A but does not carry a service signal (for example, the first optical signal only carries the CW optical signal A, further, the first optical signal is the CW optical signal A), or the first optical signal carries both the CW optical signal A and a service signal. When the first optical signal only carries the CW optical signal A, the reflected optical signal R only includes the CW reflected optical signal R1; for example, the first optical signal is the CW optical signal A, and the reflected optical signal R is the CW reflected optical signal R1. When the first optical signal carries both the CW optical signal A and a service signal, the reflected optical signal R includes the CW reflected optical signal R1 and a reflected optical signal corresponding to the service signal.

[0098] S303. The receiving device receives the second optical signal through the optical fiber link Z. The second optical signal includes the first optical signal.

[0099] The transmitting device sends a first optical signal to the receiving device through optical fiber link Z. The first optical signal is converted into a second optical signal after being transmitted through optical fiber link Z. The receiving device receives the second optical signal through optical fiber link Z.

[0100] The receiving device includes an interface corresponding to the fiber optic link Z, through which it receives the second optical signal. In a specific embodiment, the receiving device includes an optical receiver, which receives the second optical signal through the interface.

[0101] S304. The receiving device determines the target spectrum based on the second optical signal.

[0102] The receiving device processes the second optical signal to obtain the target spectrum. In an optional embodiment, the second optical signal includes a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A, and the reflected optical signal R includes a CW reflected optical signal R1. The target spectrum is the spectrum of the CW reflected optical signal R1. The receiving device determines the target spectrum of the CW reflected optical signal R1 based on the second optical signal. In a specific embodiment, the receiving device converts the second optical signal into a baseband signal, and then determines the target spectrum of the CW reflected optical signal R1 based on the baseband signal.

[0103] The following example illustrates that the second optical signal includes the first optical signal and the reflected optical signal R. The receiving device can use any of the following seven implementation methods to determine the target spectrum of the CW reflected optical signal R1.

[0104] The first implementation involves a second optical signal comprising a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A but does not carry any service signal, while the reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal may only carry the CW optical signal A, and the reflected optical signal R may only include the CW reflected optical signal R1. In another example, the first optical signal is the CW optical signal A, and the reflected optical signal R is the CW reflected optical signal R1. The receiving device converts the second optical signal into a baseband signal; the receiving device then performs a Fourier transform on the baseband signal to obtain the target spectrum of the CW reflected optical signal R1.

[0105] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes an AC reflected signal, which corresponds to the reflected optical signal R. For example, the analog AC component is the AC reflected signal corresponding to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes an AC reflected signal, which corresponds to the reflected optical signal R. For example, the digital AC component is the AC reflected signal corresponding to the reflected optical signal R. The receiving device performs a Fourier transform on the digital baseband signal to obtain the spectrum of the digital baseband signal. The spectrum of the digital baseband signal includes the spectrum of the digital DC component and the spectrum of the digital AC component, and the spectrum of the digital DC component and the spectrum of the digital AC component are separate (i.e., independent). The receiving device determines the target spectrum of the CW reflected optical signal R1 based on the spectrum of the digital baseband signal. For example, the receiving device determines the spectrum of the digital AC component in the spectrum of the digital baseband signal as the target spectrum of the CW reflected optical signal R1.

[0106] It should be noted that in this first implementation, the receiving device, by performing a Fourier transform on the digital baseband signal, can not only obtain the spectrum of the digital DC component and the spectrum of the digital AC component of the digital baseband signal, but also separate the spectrum of the digital DC component and the spectrum of the digital AC component. For example, the digital DC component of the digital baseband signal is the digital DC component corresponding to the CW optical signal A carried by the first optical signal, and the digital AC component of the digital baseband signal is the AC reflected signal corresponding to the reflected optical signal R. Furthermore, the reflected optical signal R only includes the CW reflected optical signal R1. The spectrum of the digital DC component of the digital baseband signal is the spectrum of the CW signal A, and the spectrum of the digital AC component of the digital baseband signal is the spectrum of the CW reflected optical signal R1. Therefore, in this embodiment, by performing a Fourier transform on the digital baseband signal, not only can the spectrum of the CW signal A and the spectrum of the CW reflected signal R1 be obtained, but the spectrum of the CW optical signal A and the spectrum of the CW reflected optical signal R1 can also be separated (i.e., they are independent of each other).

[0107] The second implementation involves a second optical signal comprising a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A and a service signal (or service information), while the reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal can be a service optical signal carrying the CW optical signal A and the service signal (or service information). The receiving device converts the second optical signal into a baseband signal; the receiving device filters the baseband signal to obtain a filtered signal; and the receiving device performs a Fourier transform on the filtered signal to obtain the target spectrum of the CW reflected optical signal R1.

[0108] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes a service signal and an AC reflected signal, and the AC reflected signal corresponds to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes a service signal and an AC reflected signal, which corresponds to the reflected optical signal R. The receiving device filters this digital baseband signal to obtain a filtered signal, which includes the AC reflected signal. The receiving device performs a Fourier transform on the filtered signal to obtain its spectrum, which includes the spectrum of the AC reflected signal. The receiving device determines the spectrum of the CW reflected optical signal R1 based on the spectrum of the filtered signal. For example, the receiving device determines the spectrum of the AC reflected signal within the spectrum of the filtered signal as the target spectrum of the CW reflected optical signal R1.

[0109] It should be noted that filtering the digital baseband signal by the receiving device can reduce the influence of the traffic signal on the AC reflected signal included in the digital baseband signal, thereby eliminating the influence of the traffic signal on the spectrum of the AC reflected signal. For example, the receiving device filters the digital baseband signal to remove the traffic signal, thereby eliminating the influence of the traffic signal on the AC reflected signal included in the digital baseband signal. In an optional embodiment, filtering the digital baseband signal by the receiving device can also reduce the influence of the digital DC component of the digital baseband signal on the AC reflected signal included in the digital baseband signal. For example, the receiving device filters the digital baseband signal to remove the digital DC component of the digital baseband signal, thereby eliminating the influence of the digital DC component of the digital baseband signal on the AC reflected signal included in the digital baseband signal.

[0110] Traffic signals are typically high-frequency signals. Receiving equipment can use a low-pass filter to filter the digital baseband signal to reduce (e.g., eliminate) the influence of the traffic signal on the AC reflected signals included in the digital baseband signal. Receiving equipment can also use a band-pass filter to filter the digital baseband signal to reduce (e.g., eliminate) the influence of the digital DC component of the digital baseband signal on the AC reflected signals included in the digital baseband signal.

[0111] In one embodiment, the digital baseband signal includes a digital DC component and a digital AC component, the digital AC component including a service signal and an AC reflected signal. The receiving device uses a low-pass filter to filter the digital baseband signal to obtain a filtered signal, which includes the digital DC component and the AC reflected signal. The receiving device performs a Fourier transform on the filtered signal to obtain its spectrum, which includes the spectrum of the digital DC component and the spectrum of the AC reflected signal. Furthermore, in the spectrum of the filtered signal, the spectrum of the digital DC component and the spectrum of the AC reflected signal are separate (i.e., independent). For example, the digital DC component corresponds to the CW optical signal A carried by the first optical signal, the AC reflected signal corresponds to the reflected optical signal R, and the reflected optical signal R only includes the CW reflected optical signal R1. The spectrum of the digital DC component is the spectrum of the CW signal A, and the spectrum of the AC reflected signal is the spectrum of the CW reflected optical signal R1. Therefore, by performing a Fourier transform on the filtered signal, this embodiment of the application can not only obtain the spectrum of the CW signal A and the spectrum of the CW reflected signal R1, but also separate the spectrum of the CW optical signal A and the spectrum of the CW reflected optical signal R1.

[0112] In another embodiment, the digital baseband signal includes a digital DC component and a digital AC component, the digital AC component including a service signal and an AC reflected signal. The receiving device uses a low-pass filter and a band-pass filter to filter the digital baseband signal to obtain a filtered signal, which includes the AC reflected signal. The receiving device performs a Fourier transform on the filtered signal to obtain its spectrum, which includes the spectrum of the AC reflected signal. For example, the filtered signal is the AC reflected signal, and its spectrum is the spectrum of the AC reflected signal.

[0113] The third implementation: The second optical signal includes a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A and a service signal (or service information), and the reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal is a service optical signal, carrying the CW optical signal A and the service signal (or service information). The receiving device converts the second optical signal into a baseband signal; the receiving device performs a Fourier transform on the baseband signal to obtain a first spectrum; the receiving device filters the first spectrum to obtain the target spectrum of the CW reflected optical signal R1.

[0114] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes a service signal and an AC reflected signal, and the AC reflected signal corresponds to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes a service signal and an AC reflected signal, which corresponds to the reflected optical signal R. The receiving device performs a Fourier transform on the digital baseband signal to obtain a first spectrum, which is the spectrum of the digital baseband signal. The first spectrum includes the spectrum of the digital DC component and the spectrum of the digital AC component of the digital baseband signal. Furthermore, in the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separate (i.e., they are independent). The spectrum of the digital AC component includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device filters the first spectrum to obtain a second spectrum, which includes the spectrum of the AC reflected signal. The receiving device determines the target spectrum of the CW reflected optical signal R1 based on the second spectrum. For example, the receiving device determines the spectrum of the AC reflected signal in the second spectrum as the target spectrum of the CW reflected optical signal R1.

[0115] It should be noted that filtering the first spectrum by the receiving device can reduce the influence of the service signal's spectrum on the AC reflected signal's spectrum. For example, filtering the first spectrum by the receiving device to remove the service signal's spectrum eliminates its influence on the AC reflected signal's spectrum. Furthermore, filtering the first spectrum by the receiving device can also remove the spectrum of the digital DC component.

[0116] The service signal is typically a high-frequency signal. The receiving equipment can use a low-pass filter to filter the first spectrum to reduce (e.g., eliminate) the influence of the service signal's spectrum on the AC reflected signal's spectrum. The receiving equipment can also use a band-pass filter to filter the first spectrum to remove the digital DC component's spectrum.

[0117] In one embodiment, the first spectrum includes the spectrum of the digital DC component of the digital baseband signal and the spectrum of the digital AC component of the digital baseband signal. In the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separated (i.e., they are independent of each other). The spectrum of the digital AC component includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device uses a low-pass filter to filter the first spectrum to obtain a second spectrum. The second spectrum includes the spectrum of the AC reflected signal and the spectrum of the digital DC component. In the second spectrum, the spectrum of the AC reflected signal and the spectrum of the digital DC component are separated (i.e., they are independent of each other).

[0118] In another embodiment, the first spectrum includes the spectrum of the digital DC component of the digital baseband signal and the spectrum of the digital AC component of the digital baseband signal. In the first spectrum, the spectrum of the digital DC component is separated from the spectrum of the digital AC component, which includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device uses a low-pass filter and a band-pass filter to filter the first spectrum into a second spectrum, which includes the spectrum of the AC reflected signal. For example, the second spectrum is the spectrum of the AC reflected signal.

[0119] The fourth implementation: The second optical signal includes a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A but does not carry a service signal (or service information). The reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal only carries the CW optical signal A, and the reflected optical signal R only includes the CW reflected optical signal R1. In the example, the first optical signal is the CW optical signal A, and the reflected optical signal R is the CW reflected optical signal R1. The receiving device converts the second optical signal into a baseband signal; the receiving device performs a Fourier transform on the baseband signal to obtain a first spectrum; the receiving device performs a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected optical signal R1.

[0120] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes an AC reflected signal, which corresponds to the reflected optical signal R. For example, the analog AC component is the AC reflected signal corresponding to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes an AC reflected signal, which corresponds to the reflected optical signal R. For example, the digital AC component is the AC reflected signal corresponding to the reflected optical signal R. The receiving device performs a Fourier transform on the digital baseband signal to obtain a first spectrum. The first spectrum is the spectrum of the digital baseband signal, which includes the spectrum of the digital DC component and the spectrum of the digital AC component. In the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separated (i.e., they are independent). The first spectrum has a periodic distribution characteristic. For example, the spectrum of the digital AC component in the first spectrum has a periodic distribution characteristic. The receiving device performs a Fourier transform on the first spectrum to obtain a second spectrum. The second spectrum includes the spectrum corresponding to the spectrum of the digital AC component in the first spectrum (for example, this spectrum is called spectrum G). For example, the second spectrum is spectrum G. The receiving device determines the target spectrum of the CW reflected light signal R1 based on the second spectrum. For example, the receiving device determines spectrum G in the second spectrum as the target spectrum of the CW reflected light signal R1.

[0121] The fifth implementation: The second optical signal includes a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A and a service signal (or service information), and the reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal is a service optical signal, carrying the CW optical signal A and the service signal (or service information). The receiving device converts the second optical signal into a baseband signal; the receiving device filters the baseband signal to obtain a filtered signal; the receiving device performs a Fourier transform on the filtered signal to obtain a first spectrum; the receiving device performs a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected optical signal R1.

[0122] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes a service signal and an AC reflected signal, and the AC reflected signal corresponds to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes a service signal and an AC reflected signal, which corresponds to the reflected optical signal R. The receiving device filters this digital baseband signal to obtain a filtered signal, which includes the AC reflected signal. The receiving device performs a Fourier transform on the filtered signal to obtain a first spectrum, which is the spectrum of the filtered signal and includes the spectrum of the AC reflected signal. The first spectrum has a periodic distribution characteristic. For example, the spectrum of the AC reflected signal in the first spectrum has a periodic distribution characteristic. The receiving device performs a Fourier transform on the first spectrum to obtain a second spectrum, which includes the spectrum corresponding to the spectrum of the AC reflected signal in the first spectrum (for example, this spectrum is called spectrum F). For example, the second spectrum is spectrum F. The receiving device determines the target spectrum of the CW reflected optical signal R1 based on the second spectrum. For example, the receiving device determines spectrum F in the second spectrum as the target spectrum of the CW reflected optical signal R1.

[0123] It should be noted that filtering the digital baseband signal by the receiving device can reduce the influence of the traffic signal on the AC reflected signal included in the digital baseband signal, thereby eliminating the influence of the traffic signal on the spectrum of the AC reflected signal. For example, the receiving device filters the digital baseband signal to remove the traffic signal, thereby eliminating the influence of the traffic signal on the AC reflected signal included in the digital baseband signal. In an optional embodiment, filtering the digital baseband signal by the receiving device can also reduce the influence of the digital DC component of the digital baseband signal on the AC reflected signal included in the digital baseband signal. For example, the receiving device filters the digital baseband signal to remove the digital DC component of the digital baseband signal, thereby eliminating the influence of the digital DC component of the digital baseband signal on the AC reflected signal included in the digital baseband signal.

[0124] Traffic signals are typically high-frequency signals. Receiving equipment can use a low-pass filter to filter the digital baseband signal to reduce (e.g., eliminate) the influence of the traffic signal on the AC reflected signals included in the digital baseband signal. Receiving equipment can also use a band-pass filter to filter the digital baseband signal to reduce (e.g., eliminate) the influence of the digital DC component of the digital baseband signal on the AC reflected signals included in the digital baseband signal.

[0125] In one embodiment, the digital baseband signal includes a digital DC component and a digital AC component, the digital AC component including a service signal and an AC reflected signal. The receiving device uses a low-pass filter to filter the digital baseband signal to obtain a filtered signal, which includes the digital DC component and the AC reflected signal. The receiving device performs a Fourier transform on the filtered signal to obtain a first spectrum, the first spectrum including the spectrum of the digital DC component and the spectrum of the AC reflected signal, and in the first spectrum, the spectrum of the digital DC component and the spectrum of the AC reflected signal are separate (i.e., they are independent). The receiving device performs a Fourier transform on the first spectrum to obtain a second spectrum, the second spectrum including a spectrum F corresponding to the spectrum of the AC reflected signal in the first spectrum. For example, the second spectrum is spectrum F.

[0126] In another embodiment, the digital baseband signal includes a digital DC component and a digital AC component, the digital AC component including a service signal and an AC reflected signal. The receiving device filters the digital baseband signal using a low-pass filter and a band-pass filter to obtain a filtered signal, which includes the AC reflected signal. The receiving device performs a Fourier transform on the filtered signal to obtain a first spectrum, which includes the spectrum of the AC reflected signal. For example, the first spectrum is the spectrum of the AC reflected signal. The receiving device performs a Fourier transform on the first spectrum to obtain a second spectrum, which includes a spectrum F corresponding to the spectrum of the AC reflected signal in the first spectrum. For example, the second spectrum is spectrum F.

[0127] The sixth implementation: The second optical signal includes a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A and a service signal (or service information), and the reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal is a service optical signal, carrying the CW optical signal A and the service signal (or service information). The receiving device converts the second optical signal into a baseband signal; the receiving device performs a Fourier transform on the baseband signal to obtain a first spectrum; the receiving device performs a Fourier transform on the first spectrum to obtain a second spectrum; the receiving device filters the second spectrum to obtain the target spectrum of the CW reflected optical signal R1.

[0128] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes a service signal and an AC reflected signal, and the AC reflected signal corresponds to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes a service signal and an AC reflected signal, which corresponds to the reflected light signal R. The receiving device performs a Fourier transform on the digital baseband signal to obtain a first spectrum, which is the spectrum of the digital baseband signal. The first spectrum includes the spectrum of the digital DC component and the spectrum of the digital AC component of the digital baseband signal. Furthermore, in the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separated (i.e., they are independent). The spectrum of the digital AC component includes the spectrum of the service signal and the spectrum of the AC reflected signal. The first spectrum has a periodic distribution characteristic. For example, the spectrum of the AC reflected signal in the first spectrum has a periodic distribution characteristic. The receiving device performs a Fourier transform on the first spectrum to obtain a second spectrum, which includes the spectrum corresponding to the spectrum of the digital AC component in the first spectrum (for example, this spectrum is called spectrum G). For example, the second spectrum is spectrum G. Spectrum G includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device filters the second spectrum to obtain a third spectrum, which includes the spectrum of the AC reflected signal. For example, the third spectrum is the spectrum of the AC reflected signal. The receiving device determines the target spectrum of the CW reflected optical signal R1 based on the third spectrum. For example, the receiving device determines the spectrum of the AC reflected signal in the third spectrum as the target spectrum of the CW reflected optical signal R1.

[0129] It should be noted that filtering the second spectrum by the receiving equipment can reduce the impact of the traffic signal's spectrum on the AC reflected signal's spectrum. For example, filtering the second spectrum to remove the traffic signal's spectrum can eliminate its influence on the AC reflected signal's spectrum. Since traffic signals are typically high-frequency signals, the receiving equipment can use a low-pass filter to filter the second spectrum to reduce (e.g., eliminate) the impact of the traffic signal's spectrum on the AC reflected signal's spectrum.

[0130] The seventh implementation: The second optical signal includes a first optical signal and a reflected optical signal R. The first optical signal carries a CW optical signal A and a service signal (or service information), and the reflected optical signal R includes the CW reflected optical signal R1. For example, the first optical signal is a service optical signal, carrying the CW optical signal A and the service signal (or service information). The receiving device converts the second optical signal into a baseband signal; the receiving device performs a Fourier transform on the baseband signal to obtain a first spectrum; the receiving device filters the first spectrum to obtain a second spectrum; the receiving device performs a Fourier transform on the second spectrum to obtain the target spectrum of the CW reflected optical signal R1.

[0131] In a specific embodiment, the receiving device performs photoelectric conversion on the second optical signal to obtain an analog baseband signal (i.e., an analog electrical signal). This analog baseband signal includes an analog DC component and an analog AC component. The analog DC component includes the analog DC component corresponding to the first optical signal, and may also include the analog DC component corresponding to the reflected optical signal R. Specifically, the analog DC component corresponding to the first optical signal may be the analog DC component corresponding to the CW optical signal A carried by the first optical signal. The analog AC component includes a service signal and an AC reflected signal, and the AC reflected signal corresponds to the reflected optical signal R. The receiving device performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal (i.e., a digital electrical signal). This digital baseband signal includes a digital DC component and a digital AC component. The digital DC component corresponds to the analog DC component of the analog baseband signal, and the digital AC component corresponds to the analog AC component of the analog baseband signal. The digital DC component includes the digital DC component corresponding to the first optical signal, and may also include the digital DC component corresponding to the reflected optical signal R. Specifically, the digital DC component corresponding to the first optical signal may be the digital DC component corresponding to the CW optical signal A carried by the first optical signal. The digital AC component includes a service signal and an AC reflected signal, which corresponds to the reflected optical signal R. The receiving device performs a Fourier transform on the digital baseband signal to obtain a first spectrum, which is the spectrum of the digital baseband signal. The first spectrum includes the spectrum of the digital DC component and the spectrum of the digital AC component of the digital baseband signal. Furthermore, in the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separated (i.e., they are independent). The spectrum of the digital AC component includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device filters the first spectrum to obtain a second spectrum, which includes the spectrum of the AC reflected signal. The second spectrum has a periodic distribution characteristic. For example, the spectrum of the AC reflected signal in the second spectrum has a periodic distribution characteristic. The receiving device performs a Fourier transform on the second spectrum to obtain a third spectrum, which includes the spectrum corresponding to the spectrum of the AC reflected signal in the second spectrum (for example, this spectrum is called spectrum U). For example, the third spectrum is spectrum U. The receiving device determines the target spectrum of the CW reflected optical signal R1 based on the third spectrum. For example, the receiving device determines the spectrum U in the third spectrum as the target spectrum of the CW reflected light signal R1.

[0132] It should be noted that filtering the first spectrum by the receiving device can reduce the influence of the service signal's spectrum on the AC reflected signal's spectrum. For example, filtering the first spectrum by the receiving device to remove the service signal's spectrum eliminates its influence on the AC reflected signal's spectrum. Furthermore, filtering the first spectrum by the receiving device can also remove the spectrum of the digital DC component.

[0133] The service signal is typically a high-frequency signal. The receiving equipment can use a low-pass filter to filter the first spectrum to reduce (e.g., eliminate) the influence of the service signal's spectrum on the AC reflected signal's spectrum. The receiving equipment can also use a band-pass filter to filter the first spectrum to remove the digital DC component's spectrum.

[0134] In one embodiment, the first spectrum includes the spectrum of the digital DC component of the digital baseband signal and the spectrum of the digital AC component of the digital baseband signal. In the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separated (i.e., they are independent of each other). The spectrum of the digital AC component includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device uses a low-pass filter to filter the first spectrum to obtain a second spectrum. The second spectrum includes the spectrum of the AC reflected signal and the spectrum of the digital DC component. In the second spectrum, the spectrum of the AC reflected signal and the spectrum of the digital DC component are separated. The receiving device performs a Fourier transform on the second spectrum to obtain a third spectrum. The third spectrum includes a spectrum U corresponding to the spectrum of the AC reflected signal in the second spectrum. For example, the third spectrum is spectrum U.

[0135] In another embodiment, the first spectrum includes the spectrum of the digital DC component of the digital baseband signal and the spectrum of the digital AC component of the digital baseband signal. In the first spectrum, the spectrum of the digital DC component and the spectrum of the digital AC component are separated (i.e., they are independent). The spectrum of the digital AC component includes the spectrum of the service signal and the spectrum of the AC reflected signal. The receiving device filters the first spectrum using a low-pass filter and a band-pass filter to obtain a second spectrum, which includes the spectrum of the AC reflected signal; for example, the second spectrum is the spectrum of the AC reflected signal. The receiving device performs a Fourier transform on the second spectrum to obtain a third spectrum, which includes the spectrum U corresponding to the spectrum of the AC reflected signal in the second spectrum. For example, the third spectrum is spectrum U.

[0136] It should be noted that the receiving device includes an optical receiver and an analog-to-digital converter (ADC). In the seven implementations above, the optical receiver performs photoelectric conversion on the second optical signal to obtain an analog baseband signal. The ADC performs analog-to-digital conversion on the analog baseband signal to obtain a digital baseband signal. For example, the ADC samples and quantizes the analog baseband signal to convert it into a digital baseband signal. The ADC is also called a sampling quantizer, sampling quantization unit, or analog-to-digital conversion unit, and this application embodiment does not limit this. Furthermore, the Fourier transform described in the seven implementations above can be the Fast Fourier Transform (FFT). FFT is a fast algorithm for the Discrete Fourier Transform (DFT), which is obtained by improving the DFT algorithm based on the odd, even, imaginary, and real characteristics of the Discrete Fourier Transform, thus reducing computational complexity. The embodiments of this application use FFT to determine the spectrum, resulting in lower computational complexity.

[0137] It should also be noted that the second and fifth implementations described above are illustrated using signal filtering in the time domain as an example, while the third, sixth, and seventh implementations are illustrated using signal filtering in the frequency domain as an example. In the second and fifth implementations, when the receiving device uses a low-pass filter and a band-pass filter to filter the digital baseband signal, the receiving device can first use a low-pass filter to filter the digital baseband signal, and then use a band-pass filter to filter the signal filtered by the low-pass filter; alternatively, it can first use a band-pass filter to filter the digital baseband signal, and then use a low-pass filter to filter the signal filtered by the band-pass filter. The embodiments of this application do not limit the order in which the digital baseband signal is filtered. In the third, sixth, and seventh implementations described above, when the receiving device uses a low-pass filter and a band-pass filter to filter the spectrum, the receiving device can first use a low-pass filter to filter the spectrum, and then use a band-pass filter to filter the spectrum filtered by the low-pass filter; alternatively, it can first use a band-pass filter to filter the spectrum, and then use a low-pass filter to filter the spectrum filtered by the band-pass filter. This application does not limit the order in which the spectrum is filtered. Furthermore, the receiving device can also use other methods (such as averaging or equalization) to replace the above filtering methods to achieve a similar effect to the filtering described above; this application does not limit this approach.

[0138] It should also be noted that the above description is based on the example of the second optical signal including the first optical signal and the reflected optical signal. In other embodiments, there are no anomalies in the fiber optic link, and the second optical signal includes the first optical signal but does not include the reflected optical signal (or, in other words, the second optical signal includes the first optical signal and the reflected optical signal within the tolerance range; in this case, the second optical signal is considered not to include the reflected optical signal). In this case, if the first optical signal carries CW optical signal A but does not carry a service signal (e.g., the first optical signal only carries CW optical signal A), then the analog baseband signal obtained by photoelectric conversion of the second optical signal may include an analog DC component but not an analog AC component. Furthermore, the digital baseband signal obtained by analog-to-digital conversion of the analog baseband signal may include a digital DC component but not a digital AC component. If the first optical signal carries CW optical signal A and a service signal, then the analog baseband signal obtained by photoelectric conversion of the second optical signal includes an analog DC component and an analog AC component, and the analog AC component can be the service signal. Furthermore, the digital baseband signal obtained by analog-to-digital conversion of the analog baseband signal includes a digital DC component and a digital AC component, and the digital AC component can be the service signal.

[0139] S305. The receiving device determines the transmission performance of the fiber optic link Z based on the target spectrum.

[0140] In an optional embodiment, the target spectrum is the spectrum of the CW reflected optical signal R1, and the receiving device determines the transmission performance of the optical fiber link Z based on the target spectrum of the CW reflected optical signal R1. For example, the receiving device determines whether the CW reflected optical signal R1 includes an abnormal signal based on the target spectrum of the CW reflected optical signal R1. If the CW reflected optical signal R1 includes an abnormal signal, the receiving device determines that there is an anomaly in the optical fiber link Z. Further, the receiving device determines the location of the abnormal point on the optical fiber link Z and the degree of failure of the abnormal point on the optical fiber link Z based on the target spectrum of the CW reflected optical signal R1. For example, the receiving device determines the distance between the reflecting end face of the transmitting device and at least one abnormal point on the optical fiber link Z based on the target spectrum of the CW reflected optical signal R1, and the receiving device determines the location of the at least one abnormal point based on the distance between the reflecting end face of the transmitting device and the at least one abnormal point, thereby achieving the localization of the at least one abnormal point.

[0141] In a specific embodiment, the CW reflected optical signal R1 includes at least one CW sub-reflected optical signal, which corresponds one-to-one with at least one reflecting cavity on the optical fiber link Z. Each of the at least one reflecting cavity is formed by two reflection points on the optical fiber link Z. The two reflection points forming any one reflecting cavity may include anomalies on the optical fiber link Z, and may also include the reflecting end face of the transmitting device. Each of the at least one CW sub-reflected optical signals is a signal obtained by reflecting CW optical signal A within the corresponding reflecting cavity (that is, a signal obtained by reflecting CW optical signal A between the two reflection points forming the corresponding reflecting cavity). The target spectrum of the CW reflected optical signal R1 includes at least one spectral curve, which corresponds one-to-one with the at least one CW sub-reflected optical signal, and thus corresponds one-to-one with the at least one reflecting cavity. Each of the at least one spectral curves is the spectral curve of the corresponding CW sub-reflected optical signal. The at least one CW sub-reflected optical signal may include a resonant signal, and the at least one spectral curve may include a resonant spectral curve, which is the spectral curve of the resonant signal and has multiple characteristic peaks with periodic distribution. The aforementioned abnormal signal can be a resonant signal, or it can be called a fault signal. The receiving device determines the transmission performance of the optical fiber link Z based on the at least one spectral curve. For example, the receiving device determines whether the at least one spectral curve includes a resonant spectral curve. If the at least one spectral curve includes a resonant spectral curve, the receiving device determines that the CW reflected optical signal R1 includes an abnormal signal (and determines that the abnormal signal is the resonant signal corresponding to the resonant spectral curve). Furthermore, the receiving device determines the location of the abnormal point on the optical fiber link Z and the degree of fault of the abnormal point on the optical fiber link Z based on the at least one spectral curve. For example, the receiving device determines the location of the abnormal point on the optical fiber link Z and the degree of fault of the abnormal point on the optical fiber link Z based on the resonant spectral curve in the at least one spectral curve.

[0142] In an optional embodiment, the at least one CW sub-reflected optical signal includes at least one resonant signal, and the at least one reflecting cavity includes at least one resonant cavity. Each of the at least one resonant signal corresponds one-to-one with the at least one resonant cavity. Each of the at least one resonant signal is a signal obtained by reflecting the CW optical signal A within the corresponding resonant cavity (i.e., a signal obtained by reflecting the CW optical signal A between two reflection points forming the corresponding resonant cavity). The reflection points forming the resonant cavity include anomaly points on the optical fiber link Z, and may also include the reflection end face of the transmitting device. The at least one spectral curve includes at least one resonant spectral curve, which corresponds one-to-one with the at least one resonant signal, thereby corresponding one-to-one with the at least one resonant cavity. Each of the at least one resonant spectral curves is the spectral curve of the corresponding resonant signal, and each of the at least one resonant spectral curves has multiple periodically distributed characteristic peaks. The receiving device determines that the at least one spectral curve includes the at least one resonant spectral curve, and further determines that the CW reflected optical signal R1 includes an anomalous signal (and determines that the anomalous signal is the resonant signal corresponding to the at least one resonant spectral curve). The receiving device extracts at least one resonant spectrum curve from the target spectrum. Based on this at least one resonant spectrum curve, the receiving device determines the location of the anomaly on the optical fiber link Z and the degree of failure of the anomaly on the optical fiber link Z. In a specific embodiment, the receiving device identifies at least one resonant spectrum curve in the target spectrum based on the distribution of characteristic peaks of the spectrum curves in the target spectrum, thereby determining that the target spectrum includes at least one resonant spectrum curve. The receiving device extracts the at least one resonant spectrum curve from the target spectrum and then determines the location of the anomaly on the optical fiber link Z and the degree of failure of the anomaly on the optical fiber link Z based on this at least one resonant spectrum curve. For example, the receiving device determines the length of the resonant cavity corresponding to each resonant spectrum curve based on the frequency corresponding to the characteristic peak of each resonant spectrum curve. The length of each resonant cavity is the distance between the two reflection points (including the anomaly point) forming each resonant cavity. Based on the length of the resonant cavity corresponding to each resonant spectrum curve, the receiving device determines the location of the anomaly point forming the resonant cavity corresponding to each resonant spectrum curve on the optical fiber link Z. For example, the receiving device determines the fault degree of the abnormal point of the resonant cavity corresponding to each resonant spectrum curve on the optical fiber link Z based on the amplitude of the characteristic peak of each resonant spectrum curve in the at least one resonant spectrum curve. The amplitude of the characteristic peak of each resonant spectrum curve is positively correlated with the fault degree of the abnormal point of the resonant cavity corresponding to each resonant spectrum curve.

[0143] In an optional embodiment, the at least one resonant signal includes at least one target resonant signal (it is easy to understand that the at least one resonant signal is an abnormal signal, and therefore the at least one target resonant signal is an abnormal signal). The at least one resonant cavity includes at least one target resonant cavity. The at least one target resonant signal corresponds one-to-one with the at least one target resonant cavity. Each target resonant signal is a signal obtained by reflecting the CW optical signal A within the corresponding target resonant cavity (that is, a signal obtained by reflecting the CW optical signal A between the two reflection points forming the corresponding target resonant cavity). The at least one resonant spectrum curve includes at least one target resonant spectrum curve. The at least one target resonant spectrum curve corresponds one-to-one with the at least one target resonant signal, and therefore corresponds one-to-one with the at least one target resonant cavity. Each target resonant spectrum curve is the spectrum curve of the corresponding target resonant signal, and each target resonant spectrum curve has multiple periodically distributed characteristic peaks. Each of the at least one target resonant cavity is formed by the reflective endface of the transmitting device and an anomalous point on the optical fiber link Z. The at least one target resonant signal corresponds one-to-one with the at least one anomalous point on the optical fiber link Z, and thus the at least one target resonant spectrum curve corresponds one-to-one with the at least one anomalous point. Since the reflection intensity of the reflective endface of the transmitting device is typically large (e.g., greater than the reflection intensity of the anomalous point), the intensity of the at least one target resonant signal is large, and the amplitude of the characteristic peak of the at least one target resonant spectrum curve is large. The receiving device extracts the at least one target resonant spectrum curve from the target spectrum and determines the transmission performance of the optical fiber link Z based on the at least one target resonant spectrum curve. In a specific embodiment, the receiving device identifies the at least one target resonant spectrum curve in the target spectrum based on the distribution and amplitude of the characteristic peaks of the spectrum curves in the target spectrum, and then extracts the at least one target resonant spectrum curve from the target spectrum.After the receiving device extracts the at least one target resonance spectrum curve from the target spectrum, for example, the receiving device determines the length of the target resonant cavity corresponding to each target resonance spectrum curve based on the frequency corresponding to the characteristic peak of each target resonance spectrum curve. The length of each target resonant cavity is the distance between the two reflection points forming each target resonant cavity. Each target resonant cavity is formed by the reflection end face of the transmitting device and an anomalous point on the optical fiber link Z. Therefore, the length of each target resonant cavity is the distance between the reflection end face of the transmitting device and an anomalous point on the optical fiber link Z. Based on the length of the resonant cavity corresponding to each target resonance spectrum curve (that is, the distance between the reflection end face of the transmitting device and the anomalous point corresponding to each target resonance spectrum curve), the receiving device determines the position of the anomalous point corresponding to each target resonance spectrum curve on the optical fiber link Z. For example, the receiving device determines the fault degree of the abnormal point on the optical fiber link Z corresponding to each of the at least one target resonance spectrum curves based on the amplitude of the characteristic peak of each target resonance spectrum curve. The amplitude of the characteristic peak of each target resonance spectrum curve is positively correlated with the fault degree of the abnormal point corresponding to each target resonance spectrum curve.

[0144] In an optional embodiment, the CW reflected optical signal R1 includes a first anomalous signal, and the target spectrum of the CW reflected optical signal R1 includes a first spectral curve, which is the spectral curve of the first anomalous signal. The first anomalous signal is a resonant signal, and the first spectral curve includes multiple periodically distributed characteristic peaks. In a specific embodiment, the first anomalous signal is the signal obtained by reflecting the CW optical signal A between the reflective end face of the transmitting device and the first anomalous point, and the at least one anomalous point includes the first anomalous point. For example, the reflective end face of the transmitting device and the first anomalous point form a first resonant cavity, the at least one target resonant cavity includes the first resonant cavity, the first anomalous signal is the signal formed by reflecting the CW optical signal A within the first resonant cavity, the at least one target resonant signal includes the first anomalous signal, and the at least one target resonant spectral curve includes the first spectral curve. The receiving device extracts the first spectral curve from the target spectrum of the CW reflected optical signal R1. The receiving device determines the distance between the reflective end face of the transmitting device and the first anomalous point based on the frequency corresponding to the characteristic peak of the first spectral curve, and the receiving device determines the position of the first anomalous point based on the distance between the reflective end face of the transmitting device and the first anomalous point. The receiving device determines the fault degree of the first anomaly point based on the amplitude of the characteristic peak of the first spectrum curve. The fault degree of the first anomaly point is positively correlated with the amplitude of the characteristic peak of the first spectrum curve.

[0145] Since the first abnormal signal is the signal obtained by reflecting the CW optical signal A between the reflecting end face of the transmitting device and the first abnormal point (the reflecting end face of the transmitting device corresponds to the first abnormal signal), and the first spectral curve is the spectral curve of the first abnormal signal, that is, the first spectral curve is a target resonance spectral curve, therefore, the first spectral curve not only has multiple periodically distributed characteristic peaks, but also has a large amplitude. The receiving device identifies the first spectral curve in the target spectrum based on the distribution and amplitude of the characteristic peaks of the spectral curve in the target spectrum, and then extracts the first spectral curve from the target spectrum.

[0146] The first spectral curve includes multiple periodically distributed characteristic peaks, including a primary peak and at least one secondary peak. The at least one secondary peak is a resonant peak, and the amplitude (peak value) of the at least one secondary peak is less than the amplitude (peak value) of the primary peak. The frequency corresponding to each secondary peak is greater than the frequency corresponding to the primary peak, and the frequency corresponding to each secondary peak is an integer multiple of the frequency corresponding to the primary peak. For example, the at least one secondary peak may be multiple secondary peaks, with the frequencies corresponding to these multiple secondary peaks increasing sequentially, and the frequency corresponding to each secondary peak being an integer multiple of the frequency corresponding to the primary peak. The receiving device can determine the distance between the reflecting end face of the transmitting device and the first abnormal point based on the frequency corresponding to any characteristic peak of the first spectral curve. The receiving device can determine the fault degree of the first abnormal point based on the amplitude of any characteristic peak of the first spectral curve. In an optional embodiment, the receiving device determines the distance between the reflecting end face of the transmitting device and the first abnormal point based on the frequency corresponding to the primary peak of the first spectral curve; the receiving device also determines the distance between the reflecting end face of the transmitting device and the first abnormal point based on the amplitude of the primary peak of the first spectral curve.

[0147] As an example, please refer to Figure 4, which shows a schematic diagram of a first spectrum curve provided in an embodiment of this application. The first spectrum curve includes three periodically distributed characteristic peaks: one main peak and two secondary peaks. The two secondary peaks are resonant peaks, and the amplitudes of both secondary peaks are smaller than the amplitude of the main peak. The frequency corresponding to each secondary peak is greater than the frequency corresponding to the main peak, and the frequency corresponding to each secondary peak is an integer multiple of the frequency corresponding to the main peak. For example, the two secondary peaks are secondary peak 1 and secondary peak 2. Secondary peak 1 is the resonant peak of the first harmonic, and secondary peak 2 is the resonant peak of the second harmonic. The frequency corresponding to secondary peak 1 is twice the frequency corresponding to the main peak, and the frequency corresponding to secondary peak 3 is three times the frequency corresponding to the main peak. The receiving device can determine the distance between the reflecting end face of the transmitting device and the first abnormal point based on the frequency corresponding to any one of the main peak, secondary peak 1, and secondary peak 2. The receiving device can determine the fault degree of the first abnormal point based on the amplitude of any one of the main peak, secondary peak 1, and secondary peak 2. For example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f1 corresponding to the main peak; the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the amplitude of the main peak.

[0148] In one embodiment, in S304, the receiving device determines the target spectrum of the CW reflected light signal R1 using any one of the first to third implementation methods. That is, the receiving device determines the target spectrum of the CW reflected light signal R1 through a single Fourier transform. In this case, the frequency corresponding to the characteristic peak of the first spectrum curve and the distance between the reflecting end face of the transmitting device and the first anomaly point satisfy f N= c / n / (2L)×N. c represents the speed of light, n represents the refractive index of the fiber optic link Z, L represents the distance between the reflecting end face of the transmitting device and the first anomaly point, and N is a positive integer. The symbol " / " represents division. As mentioned earlier, the receiving device can determine the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency corresponding to any characteristic peak of the first spectrum curve. N is a multiple of the frequency corresponding to that characteristic peak and the frequency corresponding to the main peak of the first spectrum curve. In the case where the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency corresponding to the main peak of the first spectrum curve, N is 1. Referring to Figure 4, in one example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f1 corresponding to the main peak, so N is 1; in another example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f2 corresponding to the secondary peak 1, so N is 2; in yet another example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f3 corresponding to the secondary peak 2, so N is 3. In a specific embodiment, the receiving device determines the frequency corresponding to any characteristic peak of the first spectrum curve, and the receiving device determines the frequency corresponding to the characteristic peak and the relationship "f N =c / n / (2L)×N”, determine the distance L between the reflecting end face of the transmitting device and the first anomaly point. The receiving device substitutes the frequency corresponding to any characteristic peak into the relation “f N =c / n / (2L)×N” to calculate the distance L between the reflecting end face of the transmitting device and the first abnormal point.

[0149] In another embodiment, in S304, the receiving device determines the target spectrum of the CW reflected light signal R1 using any one of the fourth to seventh implementation methods. That is, the receiving device determines the target spectrum of the CW reflected light signal R1 through two Fourier transforms. In this case, the frequency corresponding to the characteristic peak of the first spectrum curve and the distance between the reflecting end face of the transmitting device and the first anomaly point satisfy f N= 1 / c / n / (2L)×N. c represents the speed of light, n represents the refractive index of the fiber optic link Z, L represents the distance between the reflecting end face of the transmitting device and the first anomaly point, and N is a positive integer. The symbol " / " represents division. As mentioned earlier, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency corresponding to any characteristic peak of the first spectrum curve. N is a multiple of the frequency corresponding to that characteristic peak and the frequency corresponding to the main peak of the first spectrum curve. When the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency corresponding to the main peak of the first spectrum curve, N is 1. Referring to Figure 4, in one example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f1 corresponding to the main peak, then N is 1; in another example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f2 corresponding to the secondary peak 1, then N is 2; and in yet another example, the receiving device determines the distance between the reflecting end face of the transmitting device and the first anomaly point based on the frequency f3 corresponding to the secondary peak 2, then N is 3. In a specific embodiment, the receiving device determines the frequency corresponding to any characteristic peak of the first spectrum curve, and the receiving device determines the frequency corresponding to the characteristic peak and the relationship "f N =1 / c / n / (2L)×N” determines the distance L between the reflecting end face of the transmitting device and the first anomaly point. The receiving device substitutes the frequency corresponding to any characteristic peak into the relation “f N The distance L between the reflecting end face of the transmitting device and the first abnormal point is obtained by calculating =1 / c / n / (2L)×N”.

[0150] The above description uses the example of a receiving device determining the location and fault degree of a first anomaly point based on a first spectrum curve. The first spectrum curve is any one of the at least one target resonance spectrum curves mentioned above. The process by which the receiving device determines the location and fault degree of the corresponding anomaly point based on any one of the at least one target resonance spectrum curves can be referred to, and will not be elaborated further in this embodiment.

[0151] Furthermore, when the CW reflected light signal R1 includes at least one resonant signal, and the receiving device determines the target spectrum of the CW reflected light signal R1 through a Fourier transform, the target spectrum includes at least one resonant spectrum curve corresponding one-to-one with the at least one resonant signal. The frequency corresponding to the characteristic peak of each of the at least one resonant spectrum curves satisfies f with the length of the resonant cavity corresponding to each resonant spectrum curve. N= c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the fiber optic link Z, L represents the length of the resonant cavity, and N is a positive integer. When the CW reflected optical signal R1 includes at least one resonant signal, and the receiving device determines the target spectrum of the CW reflected optical signal R1 through two Fourier transforms, the target spectrum includes at least one resonant spectrum curve corresponding one-to-one with the at least one resonant signal. The frequency corresponding to the characteristic peak of each of the at least one resonant spectrum curves satisfies f(x) = c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the fiber optic link Z, L represents the length of the resonant cavity, and N is a positive integer. N = 1 / c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the fiber optic link Z, L represents the length of the resonant cavity, and N is a positive integer.

[0152] In summary, the technical solution provided in this application involves a transmitting device generating a first optical signal carrying a CW optical signal and then transmitting it to a receiving device via an optical fiber link. The first optical signal is then transmitted through the optical fiber link and becomes a second optical signal, which includes the first optical signal. The receiving device receives the second optical signal via the optical fiber link, determines the target spectrum based on the second optical signal, and determines the transmission performance of the optical fiber link based on the target spectrum. This enables the detection of the transmission performance of the optical fiber link. As can be seen, this application embodiment utilizes existing transmitting and receiving devices in the optical fiber communication system to detect the transmission performance of the optical fiber link. It eliminates the need for additional equipment such as OTDRs, circulators (or power dividers) in the optical fiber link to detect its transmission performance. Therefore, the hardware implementation for detecting the transmission performance of the optical fiber link is simple, the detection cost is low, and anomaly location can be achieved. In anomaly location, this application embodiment does not require personnel to carry instruments to the site for positioning or to plug and unplug optical fibers, making the process simple and enabling in-line detection.

[0153] This application embodiment uses CW optical signals to detect the transmission performance of fiber optic link Z, which avoids the impact of frequency deviation between the receiving and transmitting devices on the detection results. For example, the transmitting device typically includes a digital-to-analog converter (DAC) to convert digital baseband signals to analog baseband signals, and the receiving device typically includes an analog-to-digital converter (ADC) to convert analog baseband signals to digital baseband signals. If modulated optical signals (e.g., optical signals modulated with a detection sequence) are used to detect the transmission performance of fiber optic link Z, a frequency deviation between the ADC in the receiving device and the DAC in the transmitting device will affect the accuracy of the signal processing results. This application embodiment uses CW optical signals to detect the transmission performance of fiber optic link Z. CW optical signals are unmodulated optical signals, which can be considered as empty carrier optical signals and can be considered as carrying an all-zero sequence. Therefore, even if there is a frequency deviation between the ADC in the receiving device and the DAC in the transmitting device, the accuracy of the detection results will not be affected. Thus, the impact of frequency deviation between the ADC in the receiving device and the DAC in the transmitting device on the detection results can be avoided, ensuring the accuracy of the detection results.

[0154] This embodiment uses CW optical signals to detect the transmission performance of fiber optic link Z. When the transmitting device sends multiple optical signals, including a first optical signal, to the receiving device in parallel through the fiber optic link, crosstalk between the first optical signal and other optical signals can be avoided. Furthermore, using CW optical signals to detect the transmission performance of fiber optic link Z saves storage resources for the transmitting device. For example, if modulated optical signals (e.g., optical signals modulated with a detection sequence) are used to detect the transmission performance of fiber optic link Z, the transmitting device's storage space needs to store a long detection sequence, requiring a large storage space for the detection sequence, which easily leads to a waste of the transmitting device's storage resources. This embodiment uses CW optical signals to detect the transmission performance of fiber optic link Z, eliminating the need for the transmitting device's storage space to store the detection sequence and reducing the need for a large storage space for the detection sequence, thus saving storage resources for the transmitting device.

[0155] Based on the above description, the embodiments of this application can use either in-band detection or out-of-band detection to detect the transmission performance of an optical fiber link. In-band detection, also known as in-path detection, refers to carrying the detection signal and the service signal (or service information) in the same optical signal and transmitting it through the optical fiber link to detect the transmission performance of that link. Out-of-band detection refers to carrying the detection signal in a separate optical signal and transmitting it through the optical fiber link to detect the transmission performance of that link; that is, out-of-band detection carries the detection signal and the service signal (or service information) in different optical signals. In the embodiments of this application, the detection signal is a CW optical signal. For out-of-band detection, the transmitting device can transmit only the CW optical signal. For in-path detection, since the service optical signal (i.e., the optical signal used to carry service information) usually naturally carries the CW optical signal, the transmitting device can transmit only the service optical signal. For example, the transmitting device uses the service signal (or service information) to modulate the optical signal to generate the service optical signal.

[0156] In optional embodiments, for out-of-band detection, both the transmitting and receiving devices include switching units. The switching unit in the transmitting device controls the generation of a CW optical signal or a service optical signal (i.e., an optical signal carrying service information). The switching unit in the receiving device switches the demodulation mode, enabling the receiving device to perform fiber optic link detection or demodulation of the service signal based on the received optical signal. For example, in detection mode, the transmitting device generates a CW optical signal, and the receiving device performs fiber optic link detection based on the received optical signal. In non-detection mode, the transmitting device generates a service optical signal, and the receiving device demodulates the service signal (or service information) from the received optical signal.

[0157] In an optional embodiment, for in-band detection, the transmitting device generates a service optical signal carrying a service signal (or service information). This service optical signal inherently carries a CW optical signal. The receiving device includes a switching unit that controls whether the receiving device performs fiber optic link detection based on the received optical signal. For example, in detection mode, the receiving device demodulates the service signal from the received optical signal, and the switching unit in the receiving device controls the receiving device to perform fiber optic link detection based on the received optical signal. In non-detection mode, the receiving device demodulates the service signal from the received optical signal, and the switching unit in the receiving device controls the receiving device not to perform fiber optic link detection.

[0158] The operation of the switching unit can be controlled by a control device. The control device can be connected to both the transmitting and receiving devices to control them. For example, the control device can control the transmitting and receiving devices to be in detection mode or non-detection mode, and control the operation of the switching units in the transmitting and / or receiving devices. This embodiment of the application does not limit this specific action.

[0159] To facilitate understanding of the technical solutions of the embodiments of this application, the technical solutions of the embodiments of this application are described below with two specific examples.

[0160] Please refer to Figure 5, which shows a schematic diagram of a fiber optic link detection method provided in an embodiment of this application. Figure 5 illustrates the detection of fiber optic link transmission performance using out-of-band detection as an example. As shown in Figure 5, the control device is connected to the transmitting device 210 and the receiving device 220, respectively.

[0161] As shown in Figure 5, the transmitting device 210 includes an optical transmitter, a switching unit, and a service signal generation unit (or service information generation unit), with the switching unit connected to both the optical transmitter and the service signal generation unit. The receiving device 220 includes an optical receiver, a switching unit, a detection unit, and a service signal demodulation unit, with the switching unit connected to each of these units. The optical transmitter and optical receiver are connected via an optical fiber link 230, thus connecting the transmitting device 210 and the receiving device 220 via the same link. For example, both the transmitting device 210 and the receiving device 220 include optical modules (not shown in Figure 5). The optical module in the transmitting device 210 includes an optical transmitter, a switching unit, and a service signal generation unit, while the optical module in the receiving device 220 includes an optical receiver, a switching unit, a detection unit, and a service signal demodulation unit.

[0162] The control device controls the transmitting device 210 and the receiving device 220 to enter either a detection mode or a non-detection mode, respectively. After entering detection mode, the transmitting device 210 and the receiving device 220 cooperate to detect the transmission performance of the fiber optic link 230. After entering non-detection mode, the transmitting device 210 and the receiving device 220 perform service communication. Specifically, the control device controls the switching unit in the transmitting device 210 to disconnect the service signal generation unit from the optical transmitter, thereby controlling the transmitting device 210 to enter detection mode; the control device controls the switching unit in the receiving device 220 to connect the optical receiver to the detection unit, and also controls the switching unit in the receiving device 220 to disconnect the optical receiver from the service signal demodulation unit, thereby controlling the receiving device 220 to enter detection mode. The control device controls the switching unit in the transmitting device 210 to connect the service signal generation unit and the optical transmitter, thereby controlling the transmitting device 210 to enter the non-detection mode; the control device controls the switching unit in the receiving device 220 to disconnect the optical receiver from the detection unit, and controls the switching unit in the receiving device 220 to connect the optical receiver to the service signal demodulation unit, thereby controlling the receiving device 220 to enter the non-detection mode.

[0163] In the transmitting device 210, a service signal generation unit is used to generate a service signal (or service information), and a switching unit is used to connect or disconnect the service signal generation unit from the optical transmitter. When the service signal generation unit is disconnected from the optical transmitter, the transmitting device 210 is in detection mode. The optical transmitter generates a CW optical signal and transmits the CW optical signal to the receiving device 220 via the fiber optic link 230. When the service signal generation unit is connected to the optical transmitter, the transmitting device 210 is in non-detection mode. The optical transmitter modulates the optical signal with the service signal (or service information) generated by the service signal generation unit to generate a service optical signal. This service optical signal carries the service signal (or service information), and the optical transmitter transmits the service optical signal to the receiving device 220 via the fiber optic link 230. In the receiving device 220, the optical receiver receives the optical signal via the fiber optic link 230 and converts the optical signal into a baseband signal. The switching unit is used to control the connection between the detection unit or the service signal demodulation unit and the optical receiver. When the detection unit is connected to the optical receiver, the receiving device 220 is in detection mode. The detection unit detects the transmission performance of the optical fiber link 230 based on the baseband signal (for example, determining the target spectrum based on the baseband signal, and determining the transmission performance of the optical fiber link 230 based on the target spectrum). When the service signal demodulation unit is connected to the optical receiver, the receiving device 220 is in non-detection mode. The service signal demodulation unit demodulates the baseband signal to obtain the service signal.

[0164] In one example, both transmitting device 210 and receiving device 220 are in detection mode. The switching unit in transmitting device 210 disconnects the service signal generation unit from the optical transmitter, while the switching unit in receiving device 220 connects the detection unit to the optical receiver. The optical transmitter generates a CW optical signal and transmits it to receiving device 220 via fiber optic link 230. The optical receiver receives the carrying optical signal via fiber optic link 230 and converts it into a baseband signal. The detection unit detects the transmission performance of fiber optic link 230 based on this baseband signal. For example, the optical receiver converts the optical signal into an analog baseband signal, the detection unit converts the analog baseband signal into a digital baseband signal, the detection unit obtains the target spectrum based on the digital baseband signal, and the detection unit determines the transmission performance of fiber optic link 230 based on the target spectrum.

[0165] In another example, both transmitting device 210 and receiving device 220 are in non-detection mode. The switching unit in transmitting device 210 connects the service signal generation unit to the optical transmitter, while the switching unit in receiving device 220 disconnects the detection unit from the optical receiver. The optical transmitter modulates an optical signal with the service signal (or service information) generated by the service signal generation unit to generate a service optical signal. This service optical signal carries the service signal (or service information), and the optical transmitter transmits it to receiving device 220 via fiber optic link 230. The optical receiver receives the optical signal carrying the service signal (or service information) via fiber optic link 230 and converts it into a baseband signal. The service signal demodulation unit demodulates this baseband signal to obtain the service signal. For example, the optical receiver converts the optical signal into an analog baseband signal, the service signal demodulation unit converts the analog baseband signal into a digital baseband signal, and the service signal demodulation unit demodulates the digital baseband signal to obtain the service signal (or service information).

[0166] Please refer to Figure 6, which illustrates another fiber optic link detection method provided in this application embodiment. Figure 6 illustrates the detection of fiber optic link transmission performance using an in-band detection method as an example. As shown in Figure 6, the control device is connected to the transmitting device 210 and the receiving device 220, respectively.

[0167] As shown in Figure 6, the transmitting device 210 includes an optical transmitter and a service signal generation unit, with the optical transmitter connected to the service signal generation unit. The receiving device 220 includes an optical receiver, a switching unit, a detection unit, and a service signal demodulation unit, which are connected sequentially, and the optical receiver is connected to the service signal demodulation unit. The optical transmitter and optical receiver are connected via an optical fiber link 230, thus connecting the transmitting device 210 and the receiving device 220 via the optical fiber link 230. For example, the transmitting device 210 and the receiving device 220 each include an optical module (not shown in Figure 6). The optical module in the transmitting device 210 includes an optical transmitter and a service signal generation unit, while the optical module in the receiving device 220 includes an optical receiver, a switching unit, a detection unit, and a service signal demodulation unit.

[0168] The control device controls the receiving device 220 to enter either a detection mode or a non-detection mode. When the receiving device 220 enters detection mode, the transmitting device 210 cooperates with the receiving device 220 to detect the transmission performance of the fiber optic link 230, and the transmitting device 210 and receiving device 220 engage in service communication. When the receiving device 220 enters non-detection mode, the transmitting device 210 and receiving device 220 still engage in service communication. Specifically, the control device controls the switching unit in the receiving device 220 to connect the optical receiver and the detection unit, thereby controlling the receiving device 220 to enter detection mode. The control device also controls the switching unit in the receiving device 220 to disconnect the optical receiver from the detection unit, thereby controlling the receiving device 220 to enter non-detection mode.

[0169] In transmitting device 210, a service signal generation unit generates a service signal (or service information). An optical transmitter modulates an optical signal using the service signal (or service information) generated by the service signal generation unit to generate a service optical signal, and transmits this service optical signal to receiving device 220 via optical fiber link 230. This service optical signal carries the service signal and inherently carries a CW optical signal. In receiving device 220, an optical receiver receives the optical signal via optical fiber link 230 and converts it into a baseband signal. When receiving device 220 is in detection mode, a switching unit connects the detection unit to the optical receiver. The detection unit detects the transmission performance of optical fiber link 230 based on the baseband signal, and a service signal demodulation unit demodulates the baseband signal to obtain the service signal. When receiving device 220 is in non-detection mode, the switching unit disconnects the detection unit from the optical receiver, and the service signal demodulation unit demodulates the baseband signal to obtain the service signal.

[0170] In one example, receiving device 220 is in detection mode, and the switching unit connects the optical receiver to the detection unit. The optical transmitter modulates the optical signal with the service signal (or service information) generated by the service signal generation unit to generate a service optical signal, and transmits this service optical signal to receiving device 220 via fiber optic link 230. This service optical signal carries the service signal and inherently carries a CW optical signal. The optical receiver receives the optical signal carrying the service signal via fiber optic link 230 and converts it into a baseband signal. The detection unit detects the transmission performance of fiber optic link 230 based on the baseband signal. The service signal demodulation unit demodulates the baseband signal to obtain the service signal. For example, the optical receiver converts the optical signal into an analog baseband signal; the detection unit converts the analog baseband signal into a digital baseband signal, obtains the target spectrum based on the digital baseband signal, and determines the transmission performance of fiber optic link 230 based on the target spectrum; the service signal demodulation unit converts the analog baseband signal back into a digital baseband signal, and demodulates the digital baseband signal to obtain the service signal.

[0171] In another example, receiving device 220 is in non-detection mode, and the switching unit disconnects the optical receiver from the detection unit. The optical transmitter modulates the optical signal with the service signal (or service information) generated by the service signal generation unit to generate a service optical signal, and transmits this service optical signal to receiving device 220 via fiber optic link 230. This service optical signal carries the service signal and inherently carries a CW optical signal. The optical receiver receives the optical signal carrying the service signal via fiber optic link 230 and converts it into a baseband signal. The service signal demodulation unit demodulates the baseband signal to obtain the service signal. For example, the optical receiver converts the optical signal into an analog baseband signal; the service signal demodulation unit converts the analog baseband signal into a digital baseband signal and demodulates the digital baseband signal to obtain the service signal.

[0172] It should be noted that the light source, modulator, etc. involved in the embodiment shown in Figure 3 can all be located in the optical transmitter of the transmitting device, and the filter involved in the embodiment shown in Figure 3 can be located in the detection unit of the receiving device. This application does not limit this aspect.

[0173] The above is a description of the method embodiments of this application. The following describes the apparatus embodiments of this application, which are used to execute the method of this application. For details not disclosed in the apparatus embodiments, please refer to the method embodiments.

[0174] This application provides a fiber optic link detection device applied to the transmitting device described in the above embodiments. The detection device includes at least one functional module, which performs the operations executed by the transmitting device in the fiber optic link detection method provided in the embodiment shown in FIG3. The at least one functional module can be implemented based on software, hardware, or a combination of software and hardware, and can be arbitrarily combined or divided based on specific implementations. The detection device can be a transmitting device or a functional component within a transmitting device. For example, the detection device is a transmitting device, an optical module within a transmitting device, a fiber optic card within a transmitting device, or the detection device is integrated into the transmitting device, integrated into the optical module within the transmitting device, or integrated into the fiber optic card within the transmitting device.

[0175] As an example, please refer to Figure 7, which shows a schematic diagram of a fiber optic link detection device 700 provided in an embodiment of this application. The detection device 700 is applied to a transmitting device. The detection device 700 includes a generation module 710 and a transmission module 720.

[0176] The generation module 710 generates a first optical signal carrying a CW optical signal, which is used by the receiving device to detect the transmission performance of the optical fiber link. The transmission module 720 transmits the first optical signal to the receiving device through the optical fiber link. The functionality of the generation module 710 can be found in the description in S301 above. The functionality of the transmission module 720 can be found in the description in S302 above.

[0177] In an optional embodiment, the first optical signal is converted into a second optical signal after being transmitted via the optical fiber link. The second optical signal includes the first optical signal and a reflected optical signal. The reflected optical signal includes a CW reflected optical signal, which is a signal reflected during the transmission of the CW optical signal via the optical fiber link.

[0178] In an optional embodiment, the first optical signal also carries a service signal.

[0179] In summary, the technical solution provided in this application utilizes existing transmitting and receiving equipment in the optical fiber communication system to detect the transmission performance of the optical fiber link. It eliminates the need for additional equipment such as OTDRs, circulators (or power dividers) to be deployed within the optical fiber link, thus enabling performance testing. The hardware implementation for detecting the transmission performance of the optical fiber link is simple, the detection cost is low, and anomaly location can be achieved. Anomaly location does not require personnel to carry instruments to the site for positioning or to plug and unplug optical fibers, simplifying the process and enabling in-line detection.

[0180] This application provides another fiber optic link detection device, applied to the receiving device described in the above embodiments. The detection device includes at least one functional module, which performs the operations executed by the receiving device in the fiber optic link detection method provided in the embodiment shown in FIG3. The at least one functional module can be implemented based on software, hardware, or a combination of software and hardware, and can be arbitrarily combined or divided based on specific implementations. The detection device can be a receiving device or a functional component within a receiving device. For example, the detection device is a receiving device, an optical module within a receiving device, a fiber optic card within a receiving device, or the detection device is integrated into the receiving device, integrated into the optical module within the receiving device, or integrated into the fiber optic card within the receiving device.

[0181] As an example, please refer to Figure 8, which shows a schematic diagram of another fiber optic link detection device 800 provided in an embodiment of this application. The detection device 800 is applied to a receiving device. The detection device 800 includes a receiving module 810, a first determining module 820, and a second determining module 830.

[0182] The receiving module 810 is used to receive a second optical signal through an optical fiber link. The second optical signal includes a first optical signal. The first optical signal carries a CW optical signal, which is used by the receiving device to detect the transmission performance of the optical fiber link. The first optical signal is an optical signal generated by the transmitting device.

[0183] The first determining module 820 is used to determine the target spectrum based on the second optical signal;

[0184] The second determining module 830 is used to determine the transmission performance of the optical fiber link based on the target spectrum.

[0185] The functionality of the receiving module 810 can be referred to the relevant description in S303 above. The functionality of the first determining module 820 can be referred to the relevant description in S304 above. The functionality of the second determining module 830 can be referred to the relevant description in S305 above.

[0186] In an optional embodiment, the second optical signal further includes a reflected optical signal, which includes a CW reflected optical signal, which is a signal reflected during the transmission of the CW optical signal through the optical fiber link. The first determining module 820 is used to: determine the target spectrum of the CW reflected optical signal based on the second optical signal.

[0187] In an optional embodiment, the second determining module 830 is configured to: determine whether the CW reflected light signal includes an abnormal signal based on the target spectrum, and if the CW reflected light signal includes an abnormal signal, determine that the optical fiber link is abnormal.

[0188] In an optional embodiment, the second determining module 830 is configured to: determine the distance between the reflective end face of the transmitting device and at least one anomalous point on the optical fiber link based on the target spectrum; and determine the location of the at least one anomalous point based on the distance between the reflective end face and the at least one anomalous point.

[0189] In an optional embodiment, the target spectrum includes a first spectrum curve, which is the spectrum curve of a first abnormal signal. The first abnormal signal is the signal obtained by the CW optical signal reflected between the reflective end face and the first abnormal point. The at least one abnormal point includes the first abnormal point, and the CW reflected optical signal includes the first abnormal signal. The second determining module 830 is used to: extract the first spectrum curve from the target spectrum; and determine the distance between the reflective end face and the first abnormal point based on the frequency corresponding to the characteristic peak of the first spectrum curve.

[0190] In an optional embodiment, the first abnormal signal is a resonant signal, and the first spectral curve includes multiple characteristic peaks with periodic distribution.

[0191] In this embodiment, the target spectrum of the CW reflected light signal can be determined by a single Fourier transform or by two Fourier transforms. Determining the target spectrum of the CW reflected light signal by two Fourier transforms makes the characteristic peaks of the spectral curve more prominent, thus facilitating the determination of the frequencies corresponding to these characteristic peaks for anomaly localization. The Fourier transform can be an FFT.

[0192] The first determining module 820 can determine the target spectrum of the CW reflected light signal using any of the following seven implementation methods.

[0193] In the first implementation, the first determining module 820 is used to: convert the second optical signal into a baseband signal; and perform a Fourier transform on the baseband signal to obtain the target spectrum of the CW reflected optical signal.

[0194] In the second implementation, the first optical signal also carries a service signal. The first determining module 820 is used to: convert the second optical signal into a baseband signal; filter the baseband signal to obtain a filtered signal; and perform a Fourier transform on the filtered signal to obtain the target spectrum of the CW reflected optical signal.

[0195] In the third implementation, the first optical signal also carries a service signal. The first determining module 820 is used to: convert the second optical signal into a baseband signal; perform a Fourier transform on the baseband signal to obtain a first spectrum; and filter the first spectrum to obtain the target spectrum of the CW reflected optical signal.

[0196] The fourth implementation method, the first determining module 820, is used to: convert the second optical signal into a baseband signal; perform a Fourier transform on the baseband signal to obtain a first spectrum; and perform a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected optical signal.

[0197] In the fifth implementation, the first optical signal also carries a service signal. The first determining module 820 is used to: convert the second optical signal into a baseband signal; filter the baseband signal to obtain a filtered signal; perform a Fourier transform on the filtered signal to obtain a first spectrum; and perform a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected optical signal.

[0198] In the sixth implementation, the first optical signal also carries a service signal. The first determining module 820 is used to: convert the second optical signal into a baseband signal; perform a Fourier transform on the baseband signal to obtain a first spectrum; perform a Fourier transform on the first spectrum to obtain a second spectrum; and filter the second spectrum to obtain the target spectrum of the CW reflected optical signal.

[0199] In the seventh implementation, the first optical signal also carries a service signal. The first determining module 820 is used to: convert the second optical signal into a baseband signal; perform a Fourier transform on the baseband signal to obtain a first spectrum; filter the first spectrum to obtain a second spectrum; and perform a Fourier transform on the second spectrum to obtain the target spectrum of the CW reflected optical signal.

[0200] In an optional embodiment, the target spectrum of the CW reflected light signal is determined by a first Fourier transform. The frequency corresponding to the characteristic peak of the first spectrum curve and the distance between the reflecting end face of the transmitting device and the first anomaly point satisfy: f N = c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflecting end face and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

[0201] In an optional embodiment, the target spectrum of the CW reflected light signal is determined by two Fourier transforms. The frequency corresponding to the characteristic peak of the first spectrum curve and the distance between the reflecting end face of the transmitting device and the first anomaly point satisfy: f N = 1 / c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the fiber optic link, L represents the distance between the reflecting end face and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

[0202] In summary, the technical solution provided in this application involves a transmitting device generating a first optical signal carrying a CW optical signal and then transmitting it to a receiving device via an optical fiber link. The first optical signal is then transmitted through the optical fiber link and becomes a second optical signal, which includes the first optical signal. The receiving device receives the second optical signal via the optical fiber link, determines the target spectrum based on the second optical signal, and determines the transmission performance of the optical fiber link based on the target spectrum. This enables the detection of the transmission performance of the optical fiber link. As can be seen, this application embodiment utilizes existing transmitting and receiving devices in the optical fiber communication system to detect the transmission performance of the optical fiber link. It eliminates the need for additional equipment such as OTDRs, circulators (or power dividers) in the optical fiber link to detect its transmission performance. Therefore, the hardware implementation for detecting the transmission performance of the optical fiber link is simple, the detection cost is low, and anomaly location can be achieved. In anomaly location, this application embodiment does not require personnel to carry instruments to the site for positioning or to plug and unplug optical fibers, making the process simple and enabling in-line detection.

[0203] It should be understood that the fiber optic link detection device provided in this application embodiment can also be implemented using an application-specific integrated circuit (ASIC) or a programmable logic device (PLD). The PLD can be a complex programmable logical device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof. The fiber optic link detection method provided in the above method embodiment can also be implemented in software. When the fiber optic link detection method provided in the above method embodiment is implemented in software, each module in the fiber optic link detection device can also be a software module.

[0204] This application provides an optical fiber link detection device. The detection device includes a memory and a processor. The memory stores a computer program. The processor executes the computer program stored in the memory to cause the detection device to perform all or part of the steps of the optical fiber link detection method provided in the embodiment shown in FIG3. For example, the detection device performs steps S304, S305, etc., in the optical fiber link detection method provided in the embodiment shown in FIG3. The detection device can be a transmitting device, an optical module in the transmitting device, an optical fiber card in the transmitting device, a receiving device, an optical module in the receiving device, an optical fiber card in the receiving device, etc. The transmitting device can be a network device, a terminal device, or a server, and the receiving device can also be a network device, a terminal device, or a server.

[0205] In one embodiment, please refer to FIG9, which shows a schematic diagram of another fiber optic link detection device 900 provided in this application embodiment. The detection device 900 can be a network device, a terminal device, or a server. The detection device 900 includes at least one processor 901 (FIG. 9 illustrates two processors 901 as an example), a communication bus 902, a memory 903, and at least one communication interface 904. The at least one processor 901, the memory 903, and the at least one communication interface 904 are connected via the communication bus 902. The at least one processor 901, the memory 903, and the at least one communication interface 904 may also be connected using a connection method other than the communication bus 902.

[0206] The memory 903 is used to store the computer program that executes the technical solution of this application and is controlled by the processor 901 to execute it. The computer program stored in the memory 903 includes, but is not limited to, program code, program instructions, and data. The memory 903 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or it may be a non-volatile random access memory (NVRAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 903 can exist independently and be connected to the processor 901 via the communication bus 902. Alternatively, the memory 903 can be integrated with the processor 901; this embodiment does not limit the specific integration.

[0207] Processor 901 can be a general-purpose processor or a special-purpose processor. A general-purpose processor is a processor that performs specific steps and / or operations by reading and executing a computer program stored in memory (e.g., memory 903). In performing the aforementioned steps and / or operations, the general-purpose processor may use the computer program stored in memory (e.g., memory 903), which can be executed to implement the relevant functions of the aforementioned first determining module 820, second determining module 830, etc. General-purpose processors include, but are not limited to, central processing units (CPUs). Special-purpose processors are processors specifically designed to perform specific steps and / or operations. Special-purpose processors include, but are not limited to, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. Processor 901 can implement or execute various logic blocks, modules, and circuits described in connection with the embodiments of this application. Processor 901 can also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc. The processor can be used to: demodulate the second optical signal to obtain the detection sequence, and determine the transmission performance of the optical fiber link based on the detection sequence.

[0208] The communication bus 902 is used to transfer information between the processor 901, the communication interface 904, and the memory 903. The communication bus 902 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus 902 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is used in Figure 9, but this does not indicate that there is only one bus or one type of bus.

[0209] The communication interface 904 includes input / output (I / O) interfaces, physical interfaces, and logical interfaces for interconnecting devices within the detection device 900, as well as interfaces for interconnecting the detection device 900 with other communication devices. The physical interface can be an Ethernet interface, Fast Ethernet (FE) interface, Gigabit Ethernet (GE) interface, Terabit Ethernet (TbE) interface, 400GE interface, or Asynchronous Transfer Mode (ATM) interface, used for interconnecting the detection device 900 with other devices. The logical interface is an internal interface of the detection device 900, used for interconnecting devices within the detection device 900. It is easily understood that the communication interface 904 is used for communication between the detection device 900 and other devices or communication networks; for example, the communication interface 904 is used for the transmission and reception of optical signals between the detection device 900 and other devices or communication networks. The communication interface 904 can also be any transceiver (such as optical transmitters, optical receivers, and other optical devices), and the communication network can be Ethernet, optical transport network (OTN), secret private network (SPN), fiber channel, infinite bandwidth, etc.

[0210] In a specific implementation, as one embodiment, the detection device 900 includes a plurality of processors 901, each of which can be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. Here, a processor can refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0211] In a specific embodiment, when the detection device 900 is a transmitting device, the communication interface 904 in the detection device 900 is used to transmit a first optical signal carrying a CW optical signal via an optical fiber link. When the detection device 900 is a receiving device, the communication interface 904 in the detection device 900 is used to receive a second optical signal including the first optical signal via an optical fiber link. Correspondingly, the processor 901 in the detection device 900 is used to: determine a target spectrum based on the second optical signal, and determine the transmission performance of the optical fiber link based on the target spectrum. For detailed processing procedures of the processor 901, please refer to the relevant description in the method embodiment shown in Figure 3 above; it will not be repeated here.

[0212] In another embodiment, please refer to FIG10, which shows a schematic diagram of another fiber optic link detection device 1000 provided in this application embodiment. The detection device 1000 can be a network device, such as a switch or router, or other data communication device. As shown in FIG10, the detection device 1000 includes a main control board and one or more interface boards, the main control board being communicatively connected to the interface boards. The main control board, also called a main processing unit (MPU) or route processor card, is responsible for controlling and managing the various components in the detection device 1000, including route calculation, device management, and maintenance functions. The interface boards, also called line processing units (LPU) or line cards, are used for forwarding data. In some embodiments, the detection device 1000 may also include a switching network board, which is communicatively connected to the main control board and the interface boards. The switching network board is used for forwarding data between the interface boards, and the switching network board may also be called a switch fabric unit (SFU). The interface board includes a central processing unit, a memory, a forwarding chip, and a physical interface card (PIC). The central processing unit (CPU) is communicatively connected to the memory, forwarding chip, and physical interface card (PIC). The memory stores the forwarding table. The forwarding chip forwards received data frames based on the forwarding table stored in the memory. If the destination address of the data frame is the address of the detection device 1000, the data frame is sent to the CPU for processing; if the destination address is not the address of the detection device 1000, the next hop and outgoing interface corresponding to the destination address are found in the forwarding table, and the data frame is forwarded to the outgoing interface corresponding to the destination address. The forwarding chip can be a network processor (NP) chip. The PIC, also called a daughter card, can be installed on the interface board and is responsible for converting photoelectric signals into data frames, performing validity checks on the data frames, and forwarding them to the forwarding chip for processing. In some embodiments, the CPU can also perform the functions of the forwarding chip, such as implementing software forwarding based on a general-purpose CPU, thus eliminating the need for a forwarding chip on the interface board. Communication between the main control board, interface board, and switching network board can be achieved via a bus. The forwarding chip can be implemented using an ASIC or FPGA.

[0213] Logically, the detection device 1000 includes a control plane and a forwarding plane. The control plane includes a main control board and a central processing unit, while the forwarding plane includes various components that perform forwarding, such as a memory, a PIC, and an NP chip. The control plane performs functions such as generating forwarding tables, processing signaling and protocol messages, and configuring and maintaining status. The control plane sends the generated forwarding tables to the forwarding plane. In the forwarding plane, the NP chip uses the forwarding tables sent by the control plane to look up and forward messages received by the PIC of the detection device 1000. The forwarding tables sent by the control plane can be stored in memory. In some embodiments, the control plane and the forwarding plane can be completely separated and not on the same device.

[0214] In a specific embodiment, when the detection device 1000 is a transmitting device, the interface board in the detection device 1000 is used to generate a first optical signal carrying a CW optical signal and transmit the first optical signal through an optical fiber link. For details, please refer to the relevant descriptions in S301 to S302 above. When the detection device 1000 is a receiving device, the interface board in the detection device 1000 is used to receive a second optical signal including the first optical signal through an optical fiber link, determine the target spectrum based on the second optical signal, and determine the transmission performance of the optical fiber link based on the target spectrum. For details, please refer to the relevant descriptions in S303 to S305 above. When the detection device 1000 is a receiving device, the main control board can also be used to determine the transmission performance of the optical fiber link based on the target spectrum. For details, please refer to the relevant description in S305 above, which will not be repeated here.

[0215] In one possible implementation, an inter-process communication (IPC) channel is established between the main control board and the interface board, and the main control board and the interface board communicate with each other through the IPC channel.

[0216] This application also provides a fiber optic link detection device, including a processor and an optical device. The optical device is used to perform the transmit and receive operations in the embodiment shown in FIG3; the processor is used to perform operations other than the transmit and receive operations in the method embodiment shown in FIG3.

[0217] In an optional embodiment, the processor includes an optical digital signal processor (ODSP), and the optical device includes at least one of an optical transmitter or an optical receiver.

[0218] In an optional embodiment, the detection device is an optical module or a light card.

[0219] Based on the same inventive concept, this application provides an optical fiber communication system. The optical fiber communication system includes a transmitting device, a receiving device, and an optical fiber link. The transmitting device and the receiving device are connected via the optical fiber link. The transmitting device includes a detection device for the optical fiber link as shown in FIG. 7, FIG. 9, or FIG. 10. The receiving device includes a detection device for the optical fiber link as shown in any of FIG. 8 to FIG. 10.

[0220] For example, the fiber optic communication system is shown in any of Figures 1, 2, 5, or 6.

[0221] Based on the same inventive concept, embodiments of this application provide a computer-readable storage medium storing a computer program. When the computer program is executed (e.g., by a network device, terminal device, server, detection device, optical module, and / or optical fiber card, etc.), it implements at least some of the steps of the method embodiment shown in FIG3. For example, it implements steps S304 and S305.

[0222] Based on the same inventive concept, embodiments of this application provide a computer program product comprising a program or code that, when executed (e.g., by a network device, terminal device, server, detection device, optical module, and / or optical fiber card, etc.), implements at least some of the steps of the method embodiment shown in FIG3. For example, steps S304 and S305 are implemented.

[0223] Based on the same inventive concept, embodiments of this application provide a chip including programmable logic circuitry and / or program instructions. When the chip is executed, it is used to implement at least some of the steps of the method embodiment shown in FIG3. For example, steps S304 and S305 are implemented.

[0224] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented entirely or partially as a computer program product, which includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium, or a semiconductor medium (e.g., solid-state drive), etc.

[0225] It should be understood that the term "at least one" in this application refers to one or more, and "multiple" refers to two or more. The term "and / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. In addition, for the sake of clarity, this application uses the terms "first," "second," and "third" to distinguish identical or similar items with essentially the same function and role. The terms "first," "second," and "third" do not limit the quantity or execution order.

[0226] The different types of embodiments, such as the method embodiments and device embodiments provided in this application, can be referenced to each other. The order of operations in the method embodiments can be adjusted appropriately, and the operations can be added or removed in response to the situation. Any variations that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application, and therefore will not be described in detail.

[0227] In the corresponding embodiments provided in this application, it should be understood that the disclosed devices, etc., can be implemented through other configurations. For example, the device embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed between devices or modules may be through some interfaces, or indirect coupling or communication connection between devices or modules, which may be electrical or other forms. Modules described as separate components may or may not be physically separate, and components described as modules may or may not be physical modules; they may be located in one place or distributed across multiple network nodes. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0228] The above description is merely an exemplary embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent modifications or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for detecting an optical fiber link, characterized in that, Applied to a transmitting device, the method includes: A first optical signal is generated, the first optical signal carrying a continuous wave (CW) optical signal, the CW optical signal being used by a receiving device to detect the transmission performance of the optical fiber link; The first optical signal is transmitted to the receiving device via the optical fiber link.

2. The method according to claim 1, characterized in that, The first optical signal is transformed into a second optical signal after being transmitted through the optical fiber link. The second optical signal includes the first optical signal and a reflected optical signal. The reflected optical signal includes a CW reflected optical signal, which is a signal reflected during the transmission of the CW optical signal through the optical fiber link.

3. The method according to claim 1 or 2, characterized in that, The first optical signal also carries a service signal.

4. A method for detecting an optical fiber link, characterized in that, Applied to a receiving device, the method includes: The second optical signal is received through the optical fiber link. The second optical signal includes the first optical signal. The first optical signal carries a continuous wave (CW) optical signal. The CW optical signal is used by the receiving device to detect the transmission performance of the optical fiber link. The first optical signal is an optical signal generated by the transmitting device. The target spectrum is determined based on the second optical signal; The transmission performance of the optical fiber link is determined based on the target spectrum.

5. The method according to claim 4, characterized in that, The second optical signal also includes a reflected optical signal, which includes a CW reflected optical signal, which is a signal reflected during the transmission of the CW optical signal through the optical fiber link. Determining the target spectrum based on the second optical signal includes: The target spectrum of the CW reflected light signal is determined based on the second light signal.

6. The method according to claim 5, characterized in that, Determining the transmission performance of the optical fiber link based on the target spectrum includes: Determine the distance between the reflective end face of the transmitting device and at least one anomalous point on the optical fiber link based on the target spectrum; The location of the at least one abnormal point is determined based on the distance between the reflective end face and the at least one abnormal point.

7. The method according to claim 6, characterized in that, The target spectrum includes a first spectral curve, which is the spectral curve of a first anomalous signal. The first anomalous signal is the signal obtained by the CW optical signal reflected between the reflecting endface and the first anomalous point. The at least one anomalous point includes the first anomalous point, and the CW reflected optical signal includes the first anomalous signal. Determining the distance between the reflecting endface of the transmitting device and at least one anomalous point on the optical fiber link based on the target spectrum includes: Extract the first spectrum curve from the target spectrum; The distance between the reflecting end face and the first abnormal point is determined based on the frequency corresponding to the characteristic peak of the first spectral curve.

8. The method according to claim 7, characterized in that, The first abnormal signal is a resonant signal, and the first spectral curve includes multiple periodically distributed characteristic peaks.

9. The method according to any one of claims 5 to 8, characterized in that, Determining the target spectrum of the CW reflected light signal based on the second light signal includes: The second optical signal is converted into a baseband signal; The baseband signal is subjected to a Fourier transform to obtain the target spectrum of the CW reflected light signal.

10. The method according to any one of claims 5 to 8, characterized in that, The first optical signal also carries a service signal, and determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: The second optical signal is converted into a baseband signal; The baseband signal is filtered to obtain a filtered signal; The target spectrum of the CW reflected light signal is obtained by performing a Fourier transform on the filtered signal.

11. The method according to any one of claims 5 to 8, characterized in that, The first optical signal also carries a service signal, and determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: The second optical signal is converted into a baseband signal; Perform a Fourier transform on the baseband signal to obtain the first spectrum; The first spectrum is filtered to obtain the target spectrum of the CW reflected light signal.

12. The method according to any one of claims 9 to 11, characterized in that, The frequency corresponding to the characteristic peak of the first spectral curve and the distance between the reflecting end face and the first anomaly point satisfy: f N = c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflecting end face and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

13. The method according to any one of claims 5 to 8, characterized in that, Determining the target spectrum of the CW reflected light signal based on the second light signal includes: The second optical signal is converted into a baseband signal; Perform a Fourier transform on the baseband signal to obtain the first spectrum; Perform a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected light signal.

14. The method according to any one of claims 5 to 8, characterized in that, The first optical signal also carries a service signal, and determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: The second optical signal is converted into a baseband signal; The baseband signal is filtered to obtain a filtered signal; Perform a Fourier transform on the filtered signal to obtain the first spectrum; Perform a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected light signal.

15. The method according to any one of claims 5 to 8, characterized in that, The first optical signal also carries a service signal, and determining the target spectrum of the CW reflected optical signal based on the second optical signal includes: The second optical signal is converted into a baseband signal; Perform a Fourier transform on the baseband signal to obtain the first spectrum; Perform a Fourier transform on the first spectrum to obtain the second spectrum; The second spectrum is filtered to obtain the target spectrum of the CW reflected light signal.

16. The method according to any one of claims 13 to 15, characterized in that, The frequency corresponding to the characteristic peak of the first spectral curve and the distance between the reflecting end face and the first anomaly point satisfy: f N = 1 / c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflecting end face and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

17. A detection device for an optical fiber link, characterized in that, The detection device, applied to a transmitting device, includes: A generation module is used to generate a first optical signal, the first optical signal carrying a continuous wave (CW) optical signal, the CW optical signal being used by a receiving device to detect the transmission performance of the optical fiber link; The transmitting module is used to transmit the first optical signal to the receiving device via the optical fiber link.

18. The detection device according to claim 17, characterized in that, The first optical signal is transformed into a second optical signal after being transmitted through the optical fiber link. The second optical signal includes the first optical signal and a reflected optical signal. The reflected optical signal includes a CW reflected optical signal, which is a signal reflected during the transmission of the CW optical signal through the optical fiber link.

19. The detection device according to claim 17 or 18, characterized in that, The first optical signal also carries a service signal.

20. A detection device for an optical fiber link, characterized in that, The detection device, applied to a receiving device, includes: A receiving module is used to receive a second optical signal through the optical fiber link. The second optical signal includes a first optical signal. The first optical signal carries a continuous wave (CW) optical signal. The CW optical signal is used by the receiving device to detect the transmission performance of the optical fiber link. The first optical signal is an optical signal generated by the transmitting device. The first determining module is used to determine the target spectrum based on the second optical signal; The second determining module is used to determine the transmission performance of the optical fiber link based on the target spectrum.

21. The detection device according to claim 20, characterized in that, The second optical signal further includes a reflected optical signal, which includes a CW reflected optical signal, which is a signal reflected during the transmission of the CW optical signal via the optical fiber link. The first determining module is used to: determine the target spectrum of the CW reflected optical signal based on the second optical signal.

22. The detection device according to claim 21, characterized in that, The second determining module is used for: Determine the distance between the reflective end face of the transmitting device and at least one anomalous point on the optical fiber link based on the target spectrum; The location of the at least one abnormal point is determined based on the distance between the reflective end face and the at least one abnormal point.

23. The detection device according to claim 22, characterized in that, The target spectrum includes a first spectral curve, which is the spectral curve of a first anomalous signal. The first anomalous signal is the signal obtained by the CW optical signal reflected between the reflecting end face and the first anomalous point. The at least one anomalous point includes the first anomalous point, and the CW reflected optical signal includes the first anomalous signal. The second determining module is used for: Extract the first spectrum curve from the target spectrum; The distance between the reflecting end face and the first abnormal point is determined based on the frequency corresponding to the characteristic peak of the first spectral curve.

24. The detection device according to claim 23, characterized in that, The first abnormal signal is a resonant signal, and the first spectral curve includes multiple periodically distributed characteristic peaks.

25. The detection apparatus according to any one of claims 21 to 24, characterized in that, The first determining module is used for: The second optical signal is converted into a baseband signal; The baseband signal is subjected to a Fourier transform to obtain the target spectrum of the CW reflected light signal.

26. The detection apparatus according to any one of claims 21 to 24, characterized in that, The first optical signal also carries a service signal. The first determining module is used for: The second optical signal is converted into a baseband signal; The baseband signal is filtered to obtain a filtered signal; The target spectrum of the CW reflected light signal is obtained by performing a Fourier transform on the filtered signal.

27. The detection apparatus according to any one of claims 21 to 24, characterized in that, The first optical signal also carries a service signal. The first determining module is used for: The second optical signal baseband signal; Perform a Fourier transform on the baseband signal to obtain the first spectrum; The first spectrum is filtered to obtain the target spectrum of the CW reflected light signal.

28. The detection apparatus according to any one of claims 25 to 27, characterized in that, The frequency corresponding to the characteristic peak of the first spectral curve and the distance between the reflecting end face and the first anomaly point satisfy: f N = c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflecting end face and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

29. The detection apparatus according to any one of claims 21 to 24, characterized in that, The first determining module is used for: The second optical signal is converted into a baseband signal; Perform a Fourier transform on the baseband signal to obtain the first spectrum; Perform a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected light signal.

30. The detection apparatus according to any one of claims 21 to 24, characterized in that, The first optical signal also carries a service signal. The first determining module is used for: The second optical signal is converted into a baseband signal; The baseband signal is filtered to obtain a filtered signal; Perform a Fourier transform on the filtered signal to obtain the first spectrum; Perform a Fourier transform on the first spectrum to obtain the target spectrum of the CW reflected light signal.

31. The detection apparatus according to any one of claims 21 to 24, characterized in that, The first optical signal also carries a service signal. The first determining module is used for: The second optical signal is converted into a baseband signal; Perform a Fourier transform on the baseband signal to obtain the first spectrum; Perform a Fourier transform on the first spectrum to obtain the second spectrum; The second spectrum is filtered to obtain the target spectrum of the CW reflected light signal.

32. The detection apparatus according to any one of claims 29 to 31, characterized in that, The frequency corresponding to the characteristic peak of the first spectral curve and the distance between the reflecting end face and the first anomaly point satisfy: f N = 1 / c / n / (2L)×N, where c represents the speed of light, n represents the refractive index of the optical fiber link, L represents the distance between the reflecting end face and the first anomaly point, N is a positive integer, and the symbol " / " represents the division sign.

33. A detection device for an optical fiber link, characterized in that, Including memory and processor; The memory is used to store computer programs; The processor is configured to execute a computer program stored in the memory to cause the detection device to perform at least some of the steps in the method as described in any one of claims 1 to 16.

34. A detection device for an optical fiber link, characterized in that, Including processors and optical devices; The optical device is used to perform the transmit / receive operation in the method as described in any one of claims 1 to 16; The processor is used to perform operations other than the send / receive operation in the method as described in any one of claims 1 to 16.

35. The detection device according to claim 34, characterized in that, The processor includes an optical digital signal processor (ODSP); The optical device includes at least one of an optical transmitter or an optical receiver.

36. The detection device according to claim 34 or 35, characterized in that, The detection device is an optical module or an optical fiber card.

37. An optical fiber communication system, characterized in that, It includes a transmitting device, a receiving device, and an optical fiber link, wherein the transmitting device and the receiving device are connected via the optical fiber link; The transmitting device includes the detection device as described in any one of claims 17 to 19, 33 to 36; The receiving device includes the detection apparatus as described in any one of claims 20 to 36.

38. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements at least some of the steps in the method as described in any one of claims 1 to 16.

39. A computer program product, characterized in that, The computer program product includes a program or code that, when executed, implements at least some of the steps in the method as described in any one of claims 1 to 16.

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