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, relating to the technical field of communications. An optical transmitting device generates a first optical signal carrying a test sequence, and sends the first optical signal by means of an optical fiber link. The first optical signal is transformed into a second optical signal after being transmitted by means of the optical fiber link, the second optical signal comprising the first optical signal and a reflected optical signal. An optical receiving device receives the second optical signal by means of the optical fiber link, the optical receiving device demodulates the second optical signal to obtain the test sequence, and the optical receiving device determines the transmission performance of the optical fiber link on the basis of the demodulated test sequence. In the present application, the transmission performance of an optical fiber link is tested by using the existing optical transmitting device and optical receiving device in an optical fiber communication system, and the optical fiber link can be tested without deploying an additional device in the optical fiber link, so that the hardware implementation for testing an optical fiber link is simple, and the test costs are relatively low.

Description

Optical fiber link detection method and device, and optical fiber communication system

[0001] This application claims priority to Chinese patent application filed on January 16, 2024, with application number 202410065114.8, entitled “Detection method and device for optical fiber link, and optical fiber communication system,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a method and device for detecting an optical fiber link, and an optical fiber communication system. Background Art

[0003] A fiber-optic communication system typically includes an optical transmitter, an optical receiver, and an optical fiber link. The optical transmitter and the optical receiver are connected via the optical fiber link. The optical transmitter modulates the information to be transmitted onto an optical signal and then transmits the optical signal to the optical receiver via the optical fiber link. The optical receiver receives the optical signal via the optical fiber link and demodulates the information carried by the optical signal. Abnormalities in the optical fiber link can cause multipath interference (MPI) and mode partition noise (MPN), resulting in a degraded signal-to-noise ratio (SNR) of the optical signal received by the optical receiver. Therefore, it is necessary to test the transmission performance of the optical fiber link.

[0004] Currently, an optical time domain reflectometer (OTDR) is commonly used to test the transmission performance of an optical fiber link. For example, an OTDR is deployed in an optical fiber link, controlled to send an optical signal to the optical fiber link, and controlled to detect a reflected signal from the optical signal. The transmission performance of the optical fiber link is determined based on the reflected signal detected by the OTDR.

[0005] However, currently, detecting optical fiber links requires an additional OTDR, which makes the hardware implementation of detecting optical fiber links complex and the detection cost high.

[0006] Summary of the Invention

[0007] This application provides a method and apparatus for detecting optical fiber links, and an optical fiber communication system. The hardware implementation of optical fiber link detection in this application is simple, and the detection cost is low. The solution of this application is as follows.

[0008] In a first aspect, a method for detecting an optical fiber link is provided, which is applied to an optical transmitting device, the method comprising: generating a first optical signal, the first optical signal carrying a detection sequence, the detection sequence being used by an optical receiving device to detect the transmission performance of the optical fiber link; sending the first optical signal through the optical fiber link, the first optical signal becoming a second optical signal after being transmitted through the optical fiber link between the optical transmitting device and the optical receiving device, the second optical signal comprising the first optical signal and a reflected optical signal. The reflected optical signal is an optical signal generated by the reflection of the first optical signal in the optical fiber link. For example, the reflected optical signal is an optical signal generated by multiple (e.g., an even number of) reflections of the first optical signal between reflection points on the optical fiber link, the reflection points comprising a connector, an end face of a laser of the optical transmitting device, etc. The intensity of the reflected optical signal depends on the reflection intensity of the reflection point.

[0009] Since the second optical signal includes the first optical signal, and the first optical signal carries the detection sequence, the second optical signal carries the detection sequence.

[0010] The technical solution provided in this application can realize the detection of optical fiber links without deploying additional equipment such as OTDR in the optical fiber links. Therefore, the hardware implementation of detecting optical fiber links is simple and the detection cost is low.

[0011] Optionally, the autocorrelation curve corresponding to the detection sequence meets a preset condition.

[0012] Optionally, the autocorrelation curve corresponding to the detection sequence satisfies a preset condition, including: the autocorrelation curve corresponding to the detection sequence has one characteristic peak. For example, the autocorrelation curve corresponding to the detection sequence has only one characteristic peak.

[0013] In the technical solution provided by this application, since the autocorrelation curve corresponding to the detection sequence carried by the first optical signal has a characteristic peak, and the second optical signal includes the first optical signal, the second optical signal also carries the detection sequence, and the autocorrelation curve corresponding to the detection sequence carried by the second optical signal has a characteristic peak. This facilitates the optical receiving device to determine the transmission performance of the optical fiber link based on the characteristic peak of the autocorrelation curve corresponding to the detection sequence demodulated from the received second optical signal.

[0014] Optionally, the detection sequence includes a first sequence and a second sequence, and the autocorrelation curve corresponding to the detection sequence is determined based on the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence. The autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence. That is, the autocorrelation curve corresponding to the detection sequence is a superimposed curve of the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence.

[0015] Optionally, the first optical signal carries multiple detection sequences, and the multiple detection sequences are periodically distributed; there are boundary markers between adjacent detection sequences in the multiple detection sequences; or, adjacent detection sequences in the multiple detection sequences are continuous.

[0016] The technical solution provided by the present application is that the first optical signal carries multiple detection sequences distributed periodically (correspondingly, the second optical signal also carries multiple detection sequences distributed periodically), which facilitates the optical receiving device to demodulate the detection sequence from the second optical signal, and then determine the transmission performance of the optical fiber link based on the demodulated detection sequence. For example, if the first optical signal carries only one detection sequence (correspondingly, the second optical signal also carries only one detection sequence), the optical receiving device needs to accurately demodulate the detection sequence in order to determine the transmission performance of the optical fiber link based on the detection sequence; if the first optical signal carries multiple detection sequences (correspondingly, the second optical signal also carries multiple detection sequences), the optical receiving device only needs to demodulate one detection sequence from the multiple detection sequences to determine the transmission performance of the optical fiber link based on the detection sequence, thereby reducing the difficulty of the optical receiving device demodulating the detection sequence from the second optical signal.

[0017] Moreover, when there is a boundary identifier between adjacent detection sequences in the multiple detection sequences, the optical receiving device can identify the detection sequence carried by the second optical signal based on the boundary identifier, thereby reducing the difficulty of the optical receiving device in identifying the detection sequence carried by the second optical signal.

[0018] Optionally, the detection sequence includes any one of the following: a pseudo-random code sequence; a Gray complementary sequence.

[0019] Optionally, the first optical signal also carries a data signal, that is, the first optical signal carries a detection sequence and a data signal.

[0020] The technical solution provided in the present application carries a data signal and a detection sequence for detecting the transmission performance of an optical fiber link in the same optical signal, thereby realizing on-line detection of the transmission performance of the optical fiber link.

[0021] Optionally, in the first optical signal, a modulation depth of the detection sequence is smaller than a modulation depth of the data signal, and a baud rate of the detection sequence is smaller than a baud rate of the data signal.

[0022] The technical solution provided by the present application is that since the detection sequence is noise for the data signal, the modulation depth of the detection sequence is set to be smaller than the modulation depth of the data signal, and the baud rate of the detection sequence is set to be smaller than the baud rate of the data signal. In this way, the transmission performance of the optical fiber link can be achieved while the detection sequence is prevented from affecting the data signal.

[0023] Optionally, in the first optical signal, a ratio of a modulation depth of the detection sequence to a modulation depth of the data signal is smaller than a preset ratio; and a difference between a baud rate of the detection sequence and a baud rate of the data signal is within a preset range.

[0024] The technical solution provided by the present application is such that, since the difference between the baud rate of the detection sequence and the baud rate of the data signal is within a preset range, the baud rate of the detection sequence is lower than the baud rate of the data signal, but the baud rate of the detection sequence is not very small. In this way, while preventing the detection sequence from affecting the data signal, it is possible to prevent the baud rate of the detection sequence from being too small, making it difficult to detect the optical fiber link.

[0025] Optionally, generating the first optical signal includes: using the detection sequence to modulate a driving signal of a light source so that the light source emits the first optical signal. That is, using a direct modulation method to modulate the detection sequence into the first optical signal. Direct modulation is also called internal modulation.

[0026] Optionally, generating the first optical signal includes: using the detection sequence to modulate an optical signal emitted by a light source to obtain the first optical signal. That is, using an external modulation method to modulate the detection sequence into the first optical signal.

[0027] Optionally, generating the first optical signal includes: modulating a driving signal of a light source using a data signal modulated with the detection sequence so that the light source emits the first optical signal. That is, directly modulating the detection sequence and the data signal into the first optical signal.

[0028] Optionally, the method is performed by an optical sending device, an optical module in the optical sending device, or an optical fiber card in the optical sending device.

[0029] In a second aspect, a method for detecting an optical fiber link is provided, which is applied to an optical receiving device, and the method includes: receiving a second optical signal through the optical fiber link, the second optical signal including a first optical signal and a reflected optical signal, the first optical signal being an optical signal generated by an optical transmitting device, and the first optical signal carrying a detection sequence; demodulating the second optical signal to obtain the detection sequence; and determining the transmission performance of the optical fiber link based on the demodulated detection sequence. The reflected optical signal is an optical signal generated by the reflection of the first optical signal in the optical fiber link. For example, the reflected optical signal is an optical signal generated by multiple (for example, an even number of) reflections of the first optical signal between reflection points on the optical fiber link, and the reflection points include a connector, an end face of a laser of an optical transmitting device, etc. The intensity of the reflected optical signal depends on the reflection intensity of the reflection point.

[0030] Since the second optical signal includes the first optical signal, and the first optical signal carries the detection sequence, the second optical signal carries the detection sequence.

[0031] The technical solution provided by this application is to detect the transmission performance of the optical fiber link by cooperating with the optical transmitting device and the optical receiving device. The optical fiber link can be detected without deploying additional equipment such as OTDR in the optical fiber link. The hardware implementation of the optical fiber link detection is simple and the detection cost is low.

[0032] Optionally, the autocorrelation curve corresponding to the detection sequence meets a preset condition.

[0033] Optionally, the autocorrelation curve corresponding to the detection sequence satisfies a preset condition, including: the autocorrelation curve corresponding to the detection sequence has one characteristic peak. For example, the autocorrelation curve corresponding to the detection sequence has only one characteristic peak.

[0034] Optionally, the detection sequence includes a first sequence and a second sequence, and the autocorrelation curve corresponding to the detection sequence is determined based on the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence. The autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence. That is, the autocorrelation curve corresponding to the detection sequence is a superimposed curve of the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence.

[0035] Optionally, the first optical signal carries multiple detection sequences, and the multiple detection sequences are periodically distributed; there are boundary markers between adjacent detection sequences in the multiple detection sequences; or, adjacent detection sequences in the multiple detection sequences are continuous.

[0036] The technical solution provided by the present application is that the first optical signal carries multiple detection sequences distributed periodically (correspondingly, the second optical signal also carries multiple detection sequences distributed periodically), which facilitates the optical receiving device to demodulate the detection sequence from the second optical signal, and then determine the transmission performance of the optical fiber link based on the demodulated detection sequence. For example, if the first optical signal carries only one detection sequence (correspondingly, the second optical signal also carries only one detection sequence), the optical receiving device needs to accurately demodulate the detection sequence in order to determine the transmission performance of the optical fiber link based on the detection sequence; if the first optical signal carries multiple detection sequences (correspondingly, the second optical signal also carries multiple detection sequences), the optical receiving device only needs to demodulate one detection sequence from the multiple detection sequences to determine the transmission performance of the optical fiber link based on the detection sequence, thereby reducing the difficulty of the optical receiving device demodulating the detection sequence from the first optical signal.

[0037] Optionally, the first optical signal carries multiple detection sequences, and there are boundary identifiers between adjacent detection sequences in the multiple detection sequences. The first optical signal is demodulated to obtain the detection sequence, including: determining the multiple detection sequences carried by the second optical signal based on the boundary identifier carried by the second optical signal.

[0038] The technical solution provided by the present application is that there is a boundary identifier between adjacent detection sequences in the multiple detection sequences, and the optical receiving device identifies the detection sequence carried by the second optical signal based on the boundary identifier, thereby reducing the difficulty of the optical receiving device in identifying the detection sequence carried by the second optical signal.

[0039] Optionally, the first optical signal carries multiple detection sequences, adjacent detection sequences in the multiple detection sequences are continuous, and demodulating the second optical signal to obtain the detection sequence includes: determining the multiple detection sequences carried by the second optical signal according to characteristics of the detection sequence.

[0040] The technical solution provided by the present application is that the optical receiving device determines the detection sequence carried by the second optical signal according to the characteristics of the detection sequence, so that the optical receiving device can determine the transmission performance of the optical fiber link according to the detection sequence carried by the second optical signal.

[0041] Optionally, the transmission performance of the optical fiber link is determined based on the demodulated detection sequence, including: obtaining a correlation curve corresponding to the demodulated detection sequence, the correlation curve being an autocorrelation curve or a cross-correlation curve, the cross-correlation curve being determined based on the demodulated detection sequence and the pre-acquired detection sequence; and determining the transmission performance of the optical fiber link based on a characteristic peak of the correlation curve corresponding to the demodulated detection sequence.

[0042] In the technical solution provided by this application, the cross-correlation curve determined based on the demodulated detection sequence and the pre-acquired detection sequence can also be considered the autocorrelation curve of the detection sequence. Because the autocorrelation curve corresponding to the detection sequence carried by the first optical signal has a characteristic peak, the optical receiving device can determine the transmission performance of the optical fiber link based on the characteristic peak of the autocorrelation curve or cross-correlation curve corresponding to the detection sequence demodulated from the second optical signal.

[0043] Optionally, the transmission performance of the optical fiber link is determined based on the characteristic peak of the correlation curve corresponding to the demodulated detection sequence, including: when the correlation curve corresponding to the demodulated detection sequence has only one characteristic peak, determining that the optical fiber link is fault-free; when the correlation curve corresponding to the demodulated detection sequence has multiple characteristic peaks, determining that the optical fiber link has a fault.

[0044] The technical solution provided by the present application is that the correlation curve corresponding to the demodulated detection sequence is an autocorrelation curve or a cross-correlation curve, and the cross-correlation curve is determined based on the demodulated detection sequence and the pre-acquired detection sequence. The cross-correlation curve can also be considered as the autocorrelation curve of the detection sequence. Since the autocorrelation curve corresponding to the detection sequence modulated by the optical transmitting device on the first optical signal has a characteristic peak, when the correlation curve (autocorrelation curve or cross-correlation curve) corresponding to the detection sequence demodulated by the optical receiving device from the second optical signal has multiple characteristic peaks, it can be considered that some of these characteristic peaks are caused by noise caused by multiple reflections of the first optical signal in the optical fiber link. The fault point in the optical fiber link usually reflects the optical signal. Therefore, when the correlation curve corresponding to the detection sequence demodulated from the second optical signal has multiple characteristic peaks, the optical receiving device determines that there is a fault in the optical fiber link. When the correlation curve corresponding to the detection sequence demodulated from the second optical signal has only one characteristic peak, the optical receiving device determines that there is no fault in the optical fiber link.

[0045] Optionally, determining the transmission performance of the optical fiber link based on a characteristic peak of a correlation curve corresponding to the demodulated detection sequence further includes: if the correlation curve corresponding to the demodulated detection sequence has multiple characteristic peaks, determining a fault point on the optical fiber link based on a main peak among the multiple characteristic peaks and secondary peaks among the multiple characteristic peaks. The multiple characteristic peaks include a main peak and at least one secondary peak, and the peak value of the at least one secondary peak is smaller than the peak value of the main peak.

[0046] The technical solution provided by this application, when the correlation curve corresponding to the detection sequence demodulated from the second optical signal has multiple characteristic peaks, the optical receiving device determines the fault point on the optical fiber link based on the primary and secondary peaks among the multiple characteristic peaks, thereby locating the fault. Therefore, this application eliminates the need for personnel to carry instruments to the site for fault location, simplifying the implementation process and reducing labor costs for detection.

[0047] Optionally, the detection sequence includes any one of the following: a pseudo-random code sequence; a Gray complementary sequence.

[0048] Optionally, the first optical signal also carries a data signal, that is, the first optical signal carries a detection sequence and a data signal.

[0049] The technical solution provided in the present application carries a data signal and a detection sequence for detecting the transmission performance of an optical fiber link in the same optical signal, thereby realizing on-line detection of the transmission performance of the optical fiber link.

[0050] Optionally, in the first optical signal, a modulation depth of the detection sequence is smaller than a modulation depth of the data signal, and a baud rate of the detection sequence is smaller than a baud rate of the data signal.

[0051] The technical solution provided in this application sets the modulation depth of the detection sequence to be smaller than the modulation depth of the data signal, and the baud rate of the detection sequence to be smaller than the baud rate of the data signal. This can achieve the transmission performance of the fiber optic link during in-line detection while avoiding the detection sequence affecting the data signal.

[0052] Optionally, in the first optical signal, a ratio of a modulation depth of the detection sequence to a modulation depth of the data signal is less than a preset ratio; and a difference between a baud rate of the detection sequence and a baud rate of the data signal is within a preset range.

[0053] The technical solution provided by the present application is such that, since the difference between the baud rate of the detection sequence and the baud rate of the data signal is within a preset range, the baud rate of the detection sequence is lower than the baud rate of the data signal, but the baud rate of the detection sequence is not very small. In this way, while preventing the detection sequence from affecting the data signal, it is possible to prevent the baud rate of the detection sequence from being too small, making it difficult to detect the optical fiber link.

[0054] Optionally, demodulating the second optical signal includes filtering the second optical signal.

[0055] That is, the second optical signal is filtered to separate the detection sequence and the data signal carried by the second optical signal.

[0056] Optionally, the method is performed by an optical receiving device, an optical module in the optical receiving device, or an optical fiber card in the optical receiving device.

[0057] In a third aspect, a device for detecting an optical fiber link is provided, comprising at least one functional module configured to execute the method provided in the first aspect or any optional embodiment of the first aspect. The at least one functional module may be implemented using software, hardware, or a combination of software and hardware, and the at least one functional module may be arbitrarily combined or divided based on the specific implementation.

[0058] Optionally, the detection device is an optical transmitting device, an optical module in the optical transmitting device, or a light card in the optical transmitting device, or the detection device is integrated into the optical transmitting device, the optical module in the optical transmitting device, or the light card in the optical transmitting device.

[0059] In a fourth aspect, a device for detecting an optical fiber link is provided, comprising at least one functional module configured to execute the method provided in the second aspect or any optional embodiment of the second aspect. The at least one functional module may be implemented based on software, hardware, or a combination of software and hardware, and the at least one functional module may be arbitrarily combined or divided based on the specific implementation.

[0060] Optionally, the detection device is an optical receiving device, an optical module in an optical receiving device, or an optical card in an optical receiving device, or the detection device is integrated into the optical receiving device, an optical module in an optical receiving device, or an optical card in an optical receiving device.

[0061] In a fifth aspect, a detection device for an optical fiber link 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 so that the detection device for the optical fiber link performs the method provided in the first aspect or any optional method of the first aspect.

[0062] Optionally, the detection device is an optical transmitting device, an optical module in the optical transmitting device, or a light card in the optical transmitting device, or the detection device is integrated into the optical transmitting device, the optical module in the optical transmitting device, or the light card in the optical transmitting device.

[0063] In a sixth aspect, a detection device for an optical fiber link 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 so that the detection device for the optical fiber link performs the method provided in the second aspect or any optional method of the second aspect.

[0064] Optionally, the detection device is an optical receiving device, an optical module in an optical receiving device, or an optical card in an optical receiving device, or the detection device is integrated into the optical receiving device, an optical module in an optical receiving device, or an optical card in an optical receiving device.

[0065] In a seventh aspect, a detection device for an optical fiber link is provided, comprising a main control board and an interface board, wherein the main control board and the interface board are used to implement the method provided in the first aspect or any optional manner of the first aspect.

[0066] In an eighth aspect, a detection device for an optical fiber link is provided, comprising a main control board and an interface board, wherein the main control board and the interface board are used to implement the method provided in the second aspect or any optional manner of the second aspect.

[0067] In the ninth aspect, a detection device for an optical fiber link is provided, comprising a processor and an optical device; the optical device is used to perform the transceiver operations in the method provided in the first aspect or any optional manner of the first aspect; the processor is used to perform operations other than the transceiver operations in the method provided in the first aspect or any optional manner of the first aspect.

[0068] In the tenth aspect, a detection device for an optical fiber link is provided, comprising a processor and an optical device; the optical device is used to perform the transceiver operations in the method provided in the second aspect or any optional manner of the second aspect; the processor is used to perform operations other than the transceiver operations in the method provided in the second aspect or any optional manner of the second aspect.

[0069] Optionally, in the ninth and tenth aspects above, 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.

[0070] Optionally, in the ninth and tenth aspects above, the detection device is an optical module or an optical card.

[0071] In the eleventh aspect, a fiber optic communication system is provided, comprising an optical transmitting device, an optical receiving device and an optical fiber link, wherein the optical transmitting device is connected to the optical receiving device through the optical fiber link; the optical transmitting device comprises a detection device for an optical fiber link as provided in the third aspect, the fifth aspect, the seventh aspect or the ninth aspect above; the optical receiving device comprises a detection device for an optical fiber link as provided in the fourth aspect, the sixth aspect, the eighth aspect or the tenth aspect above.

[0072] In the twelfth aspect, a computer-readable storage medium is provided, which stores a computer program. When the computer program is executed, it implements at least part of the steps in the method provided by the first aspect or any optional manner of the first aspect, or implements at least part of the steps in the method provided by the second aspect or any optional manner of the second aspect.

[0073] In the thirteenth aspect, a computer program product is provided, which includes a program or code, and when the program or code is executed, it implements at least part of the steps in the method provided in the first aspect or any optional embodiment of the first aspect, or implements at least part of the steps in the method provided in the second aspect or any optional embodiment of the second aspect.

[0074] In the fourteenth aspect, a chip is provided, which includes a programmable logic circuit and / or program instructions, and when the chip is running, it is used to implement at least part of the steps in the method provided by the first aspect or any optional embodiment of the first aspect, or to implement at least part of the steps in the method provided by the second aspect or any optional embodiment of the second aspect.

[0075] The technical effects of the above-mentioned third to fourteenth aspects can refer to the technical effects of the first to second aspects, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] FIG1 is a schematic diagram of an optical fiber communication system provided in an embodiment of the present application;

[0077] FIG2 is a schematic diagram of an application scenario provided by an embodiment of the present application;

[0078] FIG3 is a flow chart of a method for detecting an optical fiber link provided in an embodiment of the present application;

[0079] FIG4 is a schematic diagram of a first sequence provided in an embodiment of the present application;

[0080] FIG5 is a schematic diagram of a second sequence provided in an embodiment of the present application;

[0081] FIG6 is a schematic diagram of an autocorrelation curve of a first sequence and an autocorrelation curve of a second sequence provided in an embodiment of the present application;

[0082] FIG7 is a schematic diagram of an autocorrelation curve corresponding to a detection sequence modulated in a first optical signal provided by an embodiment of the present application;

[0083] FIG8 is a schematic diagram showing a distribution of multiple detection sequences in a first optical signal provided by an embodiment of the present application;

[0084] FIG9 is a schematic diagram showing another distribution of multiple detection sequences in the first optical signal provided by an embodiment of the present application;

[0085] FIG10 is a schematic diagram of generating a first optical signal provided by an embodiment of the present application;

[0086] FIG11 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0087] FIG12 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0088] FIG13 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0089] FIG14 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0090] FIG15 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0091] FIG16 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0092] FIG17 is a schematic diagram of another method for generating a first optical signal according to an embodiment of the present application;

[0093] FIG18 is a schematic diagram of a correlation curve corresponding to a detection sequence demodulated from a second optical signal provided by an embodiment of the present application;

[0094] FIG19 is a schematic diagram of a method for detecting an optical fiber link provided in an embodiment of the present application;

[0095] FIG20 is a schematic diagram of another optical fiber link detection method provided in an embodiment of the present application;

[0096] FIG21 is a schematic diagram of a detection device for an optical fiber link provided in an embodiment of the present application;

[0097] FIG22 is a schematic diagram of another optical fiber link detection device provided in an embodiment of the present application;

[0098] FIG23 is a schematic diagram of another optical fiber link detection device provided in an embodiment of the present application;

[0099] FIG24 is a schematic diagram of another optical fiber link detection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0100] The embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

[0101] Fiber-optic communication systems use optical fibers as a transmission medium. By modulating information onto optical signals and transmitting them over optical fibers, fiber-optic communication systems enable high-speed, long-distance, and high-capacity communication.

[0102] Fiber optic communication systems typically include an optical transmitter, an optical receiver, and an optical fiber link. The optical transmitter and the optical receiver are connected via an optical fiber link. The optical transmitter modulates the information to be transmitted onto an optical signal and then transmits the optical signal to the optical receiver via the optical fiber link. The optical receiver receives the optical signal via the optical fiber link and demodulates the information carried by the optical signal. Abnormalities in the optical fiber link can cause multipath interference (MPI) noise, mode partition noise (MPN), etc., resulting in a degradation of the signal-to-noise ratio (SNR) of the optical signal received by the optical receiver. Specifically, an optical fiber link typically includes multiple sections of optical fiber and multiple connectors, which are used to connect the optical transmitter, the optical receiver, and the optical fiber. If the end face of the connector is dirty or the connector is loose, resulting in poor contact, the optical signal transmitted in the optical fiber link (for ease of distinction, this optical signal is referred to as the original optical signal) will be significantly reflected at the connector. Optical signals reflected back and forth between different connectors, as well as those reflected back and forth between connectors and the end face of the optical transmitter's laser (the end face of the optical transmitter's laser has a strong reflectivity and can be considered a fixed reflection point), can be superimposed on the original optical signal, generating MPI noise, which is related to the original optical signal but with a greater delay. The delay of MPI noise depends on the length of the optical fiber between the two reflection points (for example, two connectors, or a connector and the end face of the optical transmitter's laser). In multimode scenarios, multiple reflections caused by reflection points such as connectors and the end face of the optical transmitter's laser can also cause MPN. Both MPI noise and MPN degrade the signal-to-noise ratio (SNR) of the optical signal received by the optical receiver, affecting the transmission performance of the optical fiber transmission system and even causing optical link disconnection (a situation in which the noise superimposes on the original optical signal, preventing the optical receiver from correctly demodulating the service data carried by the original optical signal for a short period of time). The SNR of an optical signal is also known as the optical signal-to-noise ratio (OSNR). Optical transmitting equipment and optical receiving equipment are collectively referred to as optical communication equipment. Optical transmitting equipment and optical receiving equipment are relative terms. Any optical communication equipment in the optical fiber communication system can be used as an optical transmitting equipment or an optical receiving equipment.

[0103] For example, please refer to Figure 1, which shows a schematic diagram of a fiber optic communication system. The fiber optic communication system includes a site 110 and a site 120. Site 110 and site 120 are connected via a fiber optic link 130, and site 110 and site 120 are connected via a fiber optic link 140. Site 110 and site 120 are both optical communication devices. Fiber optic link 130 is a unidirectional link for communication between site 110 and site 120. Fiber optic link 130 includes multiple sections of optical fiber 131 and multiple connectors 132 (two connectors 132 are shown in Figure 1). Two adjacent sections of optical fiber 131 are connected via connectors 132. Fiber optic link 140 is a unidirectional link for communication between site 120 and site 110. Fiber optic link 140 includes multiple sections of optical fiber 141 and multiple connectors 142 (two connectors 142 are shown in Figure 1). Two adjacent sections of optical fiber 141 are connected via connectors 142. After modulating the information to be transmitted onto an optical signal, site 110 sends the optical signal (e.g., original optical signal 1) to site 120 via optical fiber link 130. Site 120 receives the optical signal via optical fiber link 130 and demodulates the information carried by the optical signal. During the transmission of original optical signal 1 in optical fiber link 130, if the end face of connector 132 in optical fiber link 130 is dirty or loose, resulting in poor contact, the original optical signal 1 will experience significant reflection at connector 132. Optical signals reflected back and forth between different connectors 132, as well as optical signals reflected back and forth between connector 132 and the end face of the laser at site 110, will be superimposed on the original optical signal 1, generating MPI noise that is related to the original optical signal 1 but has a greater delay. In multimode scenarios, multiple reflections caused by reflection points such as connector 132 and the end face of the laser can also cause MPN. Both MPI noise and MPN can degrade the signal-to-noise ratio of the optical signal received by site 120, impacting the transmission performance of the optical fiber transmission system and even causing a temporary disconnection of optical fiber link 130. Similarly, site 120 modulates the information to be transmitted onto an optical signal and then transmits this optical signal (e.g., original optical signal 2) to site 110 via optical fiber link 140. Site 110 receives the optical signal via optical fiber link 140 and demodulates the information carried by it. During the transmission of original optical signal 2 along optical fiber link 140, if the end face of connector 142 in optical fiber link 140 is dirty or loose, resulting in poor contact, original optical signal 2 can experience significant reflections at connector 142. Optical signals reflected back and forth between different connectors 142, as well as optical signals reflected back and forth between connector 142 and the end face of the laser at site 120, can be superimposed on original optical signal 2, generating MPI noise that is related to original optical signal 2 but with a greater delay. In a multimode scenario, multiple reflections caused by reflection points such as the connector 142 and the end face of the laser may also cause MPN.Both MPI noise and MPN may degrade the signal-to-noise ratio of the optical signal received by the site 110 , affecting the transmission performance of the optical fiber transmission system and even causing the optical fiber link 140 to disconnect.

[0104] Based on the above description, it can be seen that the impact of optical fiber links on the transmission performance of optical fiber transmission systems is crucial. Therefore, to prevent optical fiber link anomalies from affecting the transmission performance of optical fiber transmission systems, optical fiber link testing is necessary. For example, the length of common optical fiber links typically ranges from a few meters to tens of kilometers. Optical fiber link testing can be performed when the transmission performance of an optical fiber transmission system degrades. Alternatively, even if the transmission performance of an optical fiber transmission system has not degraded, optical fiber link testing can be performed regularly to provide early warning of transmission performance issues.

[0105] At present, an optical time domain reflectometer (OTDR) is commonly used to detect the transmission performance of an optical fiber link. OTDR detects the transmission performance of an optical fiber link based on time domain reflectometry technology, such as detecting the loss, attenuation, reflection, and fault location of the optical fiber link. For example, an OTDR is deployed in an optical fiber link, the OTDR is controlled to send an optical signal to the optical fiber link, and the OTDR is controlled to detect the reflected signal of the optical signal, and the transmission performance of the optical fiber link is determined based on the reflected signal detected by the OTDR. For example, based on the time, intensity, waveform and other information of the reflected signal detected by the OTDR, it is determined whether the optical fiber link has a fault, the fault location of the optical fiber link, etc. Specifically, the OTDR includes a laser and a detector, and the laser and the detector are deployed at the same end of the optical fiber link. The laser is used to send an optical signal to the optical fiber link, and the detector is used to detect the reflected signal of the optical signal after the laser sends the optical signal to the optical fiber link. In order for the reflected signal to be able to enter the detector, it is also necessary to set up a circulator or a power splitter on the optical fiber link, and connect the detector to the optical fiber link through the circulator or the power splitter. The reflected signal is coupled to the detector through the power splitter or the circulator to facilitate the detection of the reflected signal by the detector.

[0106] However, the solution of using OTDR to detect optical fiber links requires the deployment of hardware such as OTDR and circulator (or power splitter) in the optical fiber link, and requires the insertion and removal of optical fibers, which leads to complex hardware implementation of optical fiber link detection, high detection cost, and complicated implementation process.

[0107] In addition to using OTDR to detect fiber optic links, staff can currently carry the instrument to the site to locate fiber optic link faults. However, this solution is cumbersome to operate, the implementation process is complex, and the labor cost of detection is high.

[0108] The embodiments of the present application provide a method and device for detecting an optical fiber link, and an optical fiber communication system. The optical fiber communication system includes an optical transmitting device, an optical receiving device, and an optical fiber link, and the optical transmitting device is connected to the optical receiving device through the optical fiber link. The optical transmitting device sends an optical signal carrying a detection sequence to the optical receiving device through the optical fiber link, and the optical receiving device determines the transmission performance of the optical fiber link based on the detection sequence carried by the optical signal, thereby realizing the detection of the optical fiber link. It can be seen that the embodiments of the present application use the existing optical transmitting device and optical receiving device of the optical fiber communication system to detect the transmission performance of the optical fiber link. There is no need to deploy additional equipment such as OTDR, circulator (or power splitter) in the optical fiber link, and there is no need to plug and unplug optical fibers to realize the detection of the optical fiber link. Therefore, the hardware implementation of the optical fiber link detection is simple, the detection cost is low, and on-line detection can be realized. In addition, there is no need for staff to carry instruments to the station to locate the fault, and the labor cost of detection is low.

[0109] The technical solutions of the embodiments of the present application are introduced below, and the application scenarios of the embodiments of the present application are first introduced.

[0110] Please refer to Figure 2, which shows a schematic diagram of an application scenario provided by an embodiment of the present application. This application scenario provides a fiber optic communication system. The fiber optic communication system includes an optical transmitting device 210, an optical receiving device 220, and an optical fiber link 230. The optical transmitting device 210 and the optical receiving device 220 are connected via the optical fiber link 230. The optical fiber link 230 includes multiple sections of optical fiber 231 and multiple connectors 232, with two adjacent sections of optical fiber 231 connected by the connectors 232. The optical fiber link 230 can be a bidirectional optical fiber link between the optical transmitting device 210 and the optical receiving device 220, or it can be a unidirectional optical fiber link between the optical transmitting device 210 and the optical receiving device 220. That is, the optical fiber link 230 is used for the optical transmitting device 210 to transmit optical signals to the optical receiving device 220, and for the optical receiving device 220 to transmit optical signals to the optical transmitting device 210. Alternatively, the optical fiber link 230 is used for the optical transmitting device 210 to transmit optical signals to the optical receiving device 220, but is not used for the optical receiving device 220 to transmit optical signals to the optical transmitting device 210.

[0111] The optical transmitting device 210 and the optical receiving device 220 are collectively referred to as optical communication equipment. The optical communication equipment includes an optical module and / or a fiber card, and the optical module or the fiber card performs functions related to optical signal processing. Optionally, the optical module and / or the fiber card are pluggable and arranged in the optical communication equipment. For example, the optical communication equipment includes a slot, and the optical module and / or the fiber card is inserted into the slot to be arranged in the optical communication equipment. In an embodiment of the present application, the optical communication equipment is a network device, a terminal device or a server. The network device can be an optical transmission network device, a switch or a router, etc. The terminal device can be a personal computer (PC), a desktop computer, a printer or a camera, etc. For example, the optical module is pluggable and arranged in the optical transmission network device, the switch, the router or the terminal device, and the fiber card is pluggable and arranged in the optical transmission network device or the data communication device.

[0112] In an embodiment of the present application, the optical transmitting device 210 includes any one of a network device, a terminal device, or a server, and the optical receiving device 220 includes any one of a network device, a terminal device, or a server. The optical transmitting device 210 and the optical receiving device 220 can be the same type of optical communication device, or different types of optical communication devices. In one example, the optical transmitting device 210 and the optical receiving device 220 are both network devices, for example, both switches or routers. In another example, the optical transmitting device 210 and the optical receiving device 220 are both terminal devices, for example, both PCs or desktop computers. In yet another example, the optical transmitting device 210 and the optical receiving device 220 are both servers. In yet another example, the optical transmitting device 210 is a network device, and the optical receiving device 220 is a terminal device or a server. In yet another example, the optical transmitting device 210 is a terminal device, and the optical receiving device 220 is a network device or a server. In another example, the optical transmitting device 210 is a server, and the optical receiving device 220 is a network device or a terminal device.

[0113] In an embodiment of the present application, the optical transmitting device 210 can transmit an optical signal carrying a detection sequence to the optical receiving device 220 via the optical fiber link 230. The optical receiving device 220 receives the optical signal via the optical fiber link 230, demodulates the optical signal to obtain the detection sequence, and determines the transmission performance of the optical fiber link 230 based on the demodulated detection sequence. Thus, the optical transmitting device 210 and the optical receiving device 220 cooperate to implement the detection of the optical fiber link 230. There is no need to deploy additional equipment such as OTDR, circulator (or power splitter) in the optical fiber link 230, and there is no need to plug and unplug optical fibers to implement the detection of the optical fiber link 230. The hardware implementation of the detection of the optical fiber link 230 is simple, the detection cost is low, and on-line detection can be implemented. There is no need for staff to go down to the station to locate the fault, and the labor cost of the detection is low.

[0114] It should be noted that the application scenario shown in FIG2 is for example only and is not intended to limit the technical solution of the present 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, the number of connectors 232 included in the optical fiber link 230, etc. can be adjusted according to actual needs. In addition, the application scenario of the embodiment of the present application may also include a control device or a network management device, etc. The control device or the network management device can be connected to the optical transmitting device 210 and the optical receiving device 220 respectively, and the control device or the network management device can control the optical transmitting device 210 and the optical receiving device 220. For example, the control device or the network management device controls the optical transmitting device 210 to send an optical signal carrying a detection sequence to the optical receiving device 220 through the optical fiber link 230, and controls the optical receiving device 220 to demodulate the optical signal to obtain the detection sequence, and then the optical receiving device 220 determines the transmission performance of the optical fiber link 230 based on the demodulated detection sequence. The embodiment of the present application does not limit this.

[0115] The above is an introduction to the application scenarios of the embodiments of the present application. The following introduces the method embodiments of the present application.

[0116] Please refer to Figure 3, which shows a flow chart of a method for detecting an optical fiber link provided in an embodiment of the present application. This detection method is performed by an optical transmitter and an optical receiver in a fiber optic communication system. For example, the fiber optic communication system is shown in Figure 2, and this detection method is performed by optical transmitter 210 and optical receiver 220 in cooperation. Referring to Figure 3, this detection method includes the following steps S301 to S305.

[0117] S301. An optical transmitting device generates a first optical signal. The first optical signal carries a detection sequence X. The detection sequence X is used by an optical receiving device to detect the transmission performance of an optical fiber link Z.

[0118] For example, the optical transmitting device is the optical transmitting device 210 in the optical fiber communication system shown in FIG. 2 , and the optical fiber link Z is the optical fiber link 230 .

[0119] In an optional embodiment, the autocorrelation curve corresponding to the detection sequence X meets a preset condition.

[0120] In an optional embodiment, the autocorrelation curve corresponding to the detection sequence X satisfies a preset condition including: the autocorrelation curve corresponding to the detection sequence X has a characteristic peak. For example, the autocorrelation curve corresponding to the detection sequence X has only one characteristic peak. For example, the autocorrelation curve corresponding to the detection sequence X has only one characteristic peak, and the autocorrelation values ​​of each position point on the autocorrelation curve corresponding to the detection sequence X except for the characteristic peak are all small (for example, very small). For example, the autocorrelation values ​​of each position point on the autocorrelation curve corresponding to the detection sequence X except for the characteristic peak are all 0. In one example, the detection sequence X includes any one of a pseudo random binary sequence (PRBS) or a Gray complementary sequence. The Gray complementary sequence is a pulse coding sequence. The autocorrelation curve corresponding to the PRBS and the autocorrelation curve corresponding to the Gray complementary sequence both have a characteristic peak, so the embodiment of the present application can use PRBS or Gray complementary sequence as the detection sequence X.

[0121] In an optional embodiment, the detection sequence X includes a first sequence A and a second sequence B, and the autocorrelation curve corresponding to the detection sequence X is determined based on the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B. For example, the autocorrelation curve corresponding to the detection sequence X is a superimposed curve of the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B. The position points on the autocorrelation curve corresponding to the detection sequence X, the position points on the autocorrelation curve of the first sequence A, and the position points on the autocorrelation curve of the second sequence B correspond one to one. The autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence X is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence A and the autocorrelation value of the position point on the autocorrelation curve of the second sequence B. The autocorrelation curve of each sequence in the first sequence A and the second sequence B has at least one peak, the at least one peak including a main peak and further including a secondary peak. The peak value of the main peak (i.e., the autocorrelation value of the main peak) is greater than a first threshold, and the peak value of the secondary peak (i.e., the autocorrelation value of the secondary peak) is less than a second threshold. The first threshold is greater than the second threshold, and the difference between the first threshold and the second threshold is greater than a preset difference. The first threshold, the second threshold, and the preset difference can all be set according to actual conditions. That is, on the autocorrelation curve of each sequence in the first sequence A and the second sequence B, the peak value of the main peak is relatively large (e.g., very large), and the peak value of the secondary peak is relatively small (e.g., very small). For example, the peak value of the main peak of the autocorrelation curve of the first sequence A is very large, and the autocorrelation values ​​of each position point on the autocorrelation curve of the first sequence A except the main peak are all very small, the peak value of the main peak of the autocorrelation curve of the second sequence B is very large, and the autocorrelation values ​​of each position point on the autocorrelation curve of the second sequence B except the main peak are all very small, and the autocorrelation values ​​of each position point on the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B except the main peak are opposite, thereby making the autocorrelation curve corresponding to the detection sequence X determined based on the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B (e.g., the superposition curve of the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B) have only one characteristic peak, and the autocorrelation values ​​of each position point on the autocorrelation curve except the characteristic peak are all 0. In one embodiment, in the detection sequence X, the second sequence B is located after the first sequence A, and the second sequence B is adjacent to the first sequence A. The lengths of the first sequence A and the second sequence B are both fixed, and the lengths of the first sequence A and the second sequence B may be equal or unequal. For example, the lengths of the first sequence A and the second sequence B are equal.

[0122] In one example, the first sequence A is 1, 1, 1, -1, 1, 1, -1, 1, and the second sequence B is 1, 1, 1, -1, -1, -1, 1, -1. The first sequence A is shown in FIG4 (the horizontal axis represents the number of symbols included in the first sequence A, and the vertical axis represents the amplitude of the symbols included in the first sequence A), and the second sequence B is shown in FIG5 (the horizontal axis represents the number of symbols included in the second sequence B, and the vertical axis represents the amplitude of the symbols included in the second sequence B). The autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B are shown in FIG6. Referring to FIG6, the main peak of the autocorrelation curve of the first sequence A is very large, and the autocorrelation values ​​of each position point on the autocorrelation curve of the first sequence A except the main peak are very small. The main peak of the autocorrelation curve of the second sequence B is very large, and the autocorrelation values ​​of each position point on the autocorrelation curve of the second sequence B except the main peak are very small. In addition, the autocorrelation values ​​of each position point on the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B except the main peak are opposite. For example, the detection sequence X includes a first sequence A and a second sequence B, where the second sequence B is located after the first sequence A and is adjacent to the first sequence A. The detection sequence X is 1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, -1, 1, -1. The autocorrelation curve corresponding to the detection sequence X is the superposition of the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B (the superposition of the two curves in FIG6 ). The autocorrelation curve corresponding to the detection sequence X is shown in FIG7 . Referring to FIG7 , the autocorrelation curve corresponding to the detection sequence X has a characteristic peak, and the autocorrelation values ​​of all positions on the autocorrelation curve except the characteristic peak are 0. In FIG6 and FIG7 , the horizontal axis represents the number of time-shifted symbols, and the vertical axis represents the autocorrelation value (i.e., the correlation degree). It should be noted that when obtaining the autocorrelation curve of a sequence, one of the two sequences needs to be shifted by a certain number of symbols (i.e., the time-shift symbol number) relative to the other. In Figures 6 and 7, negative and positive time-shift symbol numbers indicate different shift directions. For example, a negative time-shift symbol number indicates a shift to the left, while a positive time-shift symbol number indicates a shift to the right.

[0123] In an optional embodiment, the detection sequence X is a Golay complementary sequence. There are many methods for generating a Golay complementary sequence. For example, a Golay complementary sequence of length 2L can be generated from a Golay complementary sequence of length L, a Golay complementary sequence of length 4L can be generated from a Golay complementary sequence of length 2L, a Golay complementary sequence of length 8L can be generated from a Golay complementary sequence of length 4L, and so on.

[0124] For example, the Golay complementary sequence is generated by the recursive method shown in the following formula (1). A high-order Golay complementary sequence (ie, a long Golay complementary sequence) can be generated based on a low-order Golay complementary sequence (ie, a short Golay complementary sequence) and the following formula (1).

[0125] In the above formula (1), the symbol “|” represents connection, and “A|B” means putting sequence B to the right (or behind) of sequence A. Indicates the inversion of B. For example, if B=1, then If B = -1, then

[0126] In one example, the Golay complementary sequence of length 1 is The process of generating a Golay complementary sequence with a length of 2 according to the Golay complementary sequence with a length of 1 is shown in the following formula (2).

[0127] The process of generating a Golay complementary sequence with a length of 4 according to the Golay complementary sequence with a length of 2 is shown in the following formula (3).

[0128] The process of generating a Golay complementary sequence with a length of 8 from the Golay complementary sequence with a length of 4 is shown in the following formula (4).

[0129] By analogy, a higher-order Gray complementary sequence can be generated. For example, a Gray complementary sequence of length 16 is generated based on a Gray complementary sequence of length 8, a Gray complementary sequence of length 32 is generated based on a Gray complementary sequence of length 16, and a Gray complementary sequence of length 64 is generated based on a Gray complementary sequence of length 32. For example, as mentioned above, the first sequence A is 1,1,1,-1,1,1,-1,1, and the second sequence B is 1,1,1,-1,-1,-1,-1,1,-1. According to the above formula (4), the first sequence A and the second sequence B are two subsets of the Gray complementary sequence of length 8 expressed by the above formula (4). The detection sequence X can be the Gray complementary sequence expressed by the above formula (4) or a higher-order Gray complementary sequence. In the embodiment of the present application, the detection sequence X is taken as an example of the Gray complementary sequence expressed by the above formula (4). The autocorrelation curve corresponding to the detection sequence X is shown in Figure 7.

[0130] The above description uses the example of determining the autocorrelation curve corresponding to the detection sequence X based on the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B, and primarily uses the example of the detection sequence X being a Golay complementary sequence. The above description of the autocorrelation curve corresponding to the detection sequence X is also applicable to the case where the detection sequence X is a pseudorandom code sequence. In the case where the detection sequence X is a pseudorandom code sequence, an autocorrelation calculation can also be directly performed on the detection sequence X to obtain the autocorrelation curve of the detection sequence X, which is not limited in this embodiment of the present application.

[0131] In an optional embodiment, the first optical signal carries multiple detection sequences X, and the multiple detection sequences X are distributed periodically. That is, the multiple detection sequences X are distributed periodically in the first optical signal. Among them, the multiple detection sequences X can all be used by the optical receiving device to detect the transmission performance of the optical fiber link Z. After the first optical signal is transmitted through the optical fiber link Z between the optical transmitting device and the optical receiving device, it becomes a second optical signal. The second optical signal includes the first optical signal and a reflected optical signal. The reflected optical signal is an optical signal generated by the first optical signal being reflected in the optical fiber link Z multiple times (for example, an even number of times) between reflection points on the optical fiber link Z. The reflection points include the connector, the end face of the laser of the optical transmitting device, etc. The intensity of the reflected optical signal depends on the reflection intensity of the reflection point. In the embodiment of the present application, the first optical signal carries multiple detection sequences X. Therefore, the second optical signal also carries the multiple detection sequences X. This makes it easier for the optical receiving device to demodulate the detection sequence X from the second optical signal, and then determine the transmission performance of the optical fiber link Z based on the demodulated detection sequence X. For example, if the first optical signal carries only one detection sequence X, then the second optical signal also carries only one detection sequence X. The optical receiving device needs to accurately demodulate the detection sequence X from the second optical signal in order to determine the transmission performance of the optical fiber link Z based on the detection sequence X. However, if the first optical signal carries multiple detection sequences X, then the second optical signal also carries multiple detection sequences X. As long as the optical receiving device can demodulate any one of the multiple detection sequences X from the second optical signal, it can determine the transmission performance of the optical fiber link Z based on the detection sequence X demodulated from the second optical signal. This reduces the difficulty for the optical receiving device to demodulate the detection sequence X from the second optical signal.

[0132] In one embodiment, the first optical signal carries multiple detection sequences X, which are periodically distributed, and there are boundary markers between adjacent detection sequences X in the multiple detection sequences X. The boundary marker is used by the optical receiving device to determine the starting position and / or ending position of the detection sequence X, thereby determining the detection sequence X. For example, the boundary marker is an idle sequence. The idle sequence can be an all-0 sequence (that is, all symbols in the idle sequence are 0), or a sequence with an amplitude less than the amplitude of the detection sequence, for example, the amplitude of the idle sequence is half the amplitude of the detection sequence. As an example, please refer to Figure 8, which shows a schematic diagram of the distribution of multiple detection sequences X in the first optical signal. The first optical signal carries n detection sequences X, and there are boundary markers between adjacent detection sequences X. The n detection sequences X are periodically distributed, and each period has one detection sequence X and one boundary marker, where n is a positive integer. The length of the detection sequence X can be different from the length of the boundary marker, and the length of the detection sequence X and the length of the boundary marker are both set according to actual conditions. When the length of the boundary marker is 0, it can be considered that there is no boundary marker. When the length of the boundary marker is greater than 0, it can be considered that there is a boundary marker between adjacent detection sequences X in the multiple detection sequences X, and it can be considered that there is a gap between the adjacent detection sequences X, or the adjacent detection sequences X are discontinuous.

[0133] In another embodiment, the first optical signal carries a plurality of detection sequences X, the plurality of detection sequences X are periodically distributed, adjacent detection sequences X in the plurality of detection sequences X are continuous, there are no boundary markers between adjacent detection sequences X in the plurality of detection sequences X, and there are no gaps between adjacent detection sequences X in the plurality of detection sequences X. As an example, please refer to Figure 9, which shows another distribution diagram of the plurality of detection sequences X in the first optical signal. The first optical signal carries n detection sequences X, adjacent detection sequences X in the plurality of detection sequences X are continuous, there are no gaps between adjacent detection sequences X, the n detection sequences X are periodically distributed, and there is one detection sequence X in each period, where n is a positive integer. The length of the detection sequence X is a specific length, and the length of the detection sequence X can be set according to actual conditions.

[0134] In an optional embodiment, the first optical signal also carries a data signal Y. That is, the first optical signal carries a detection sequence X and a data signal Y. Thus, in the embodiment of the present application, the detection sequence X and the data signal Y are carried in the same optical signal, which can achieve the transmission performance of the on-link detection optical fiber link Z. Since the detection sequence X is noise with respect to the data signal Y, in the first optical signal, the modulation depth of the detection sequence X is less than the modulation depth of the data signal Y, and the baud rate of the detection sequence X is less than the baud rate of the data signal Y. In this way, the detection sequence X can be prevented from affecting the data signal Y while achieving the transmission performance of the on-link detection optical fiber link Z.

[0135] In an optional embodiment, in the first optical signal, the ratio of the modulation depth of the detection sequence X to the modulation depth of the data signal Y is less than a preset ratio, and the difference between the baud rate of the detection sequence X and the baud rate of the data signal Y is within a preset range. The preset ratio and the preset range can be set according to actual conditions. For example, the preset ratio is 0.1, and the preset range is several MHz (megahertz) to several GHz (gigahertz). Since the ratio of the modulation depth of the detection sequence X to the modulation depth of the data signal Y is less than the preset ratio, the baud rate of the detection sequence X is less than the baud rate of the data signal Y, and the difference between the baud rate of the detection sequence X and the baud rate of the data signal Y is within a preset range, it is possible to avoid the detection sequence X affecting the data signal Y while avoiding the baud rate of the detection sequence X being too small, making it difficult to detect the optical fiber link Z.

[0136] In an embodiment of the present application, the optical transmitting device may generate a first optical signal using a direct modulation method and / or an external modulation method. The direct modulation method refers to a method of performing modulation within a light source, specifically a modulation method of directly controlling the light source (for example, if the light source is a laser, directly controlling the pump source of the laser) to modulate the optical signal emitted by the light source. The direct modulation method is also called an internal modulation method. The external modulation method refers to a method of performing modulation outside the light source, specifically a method of using a modulator outside the light source to modulate the optical signal emitted by the light source. In an embodiment of the present application, the light source may be any of various possible light sources such as a laser or a laser diode (LD), and the laser may include any of a vertical cavity surface emitting laser (VCSEL), an electro-absorption modulated laser (EML), and a directly modulated laser (DML). The modulator may be any of various possible modulators such as a Mach-Zehnder modulator (MZM) and an electrically variable optical attenuator (EVOA). The embodiments of the present application do not limit the light source and the modulator.

[0137] The following describes two implementations of how the optical sending device generates the first optical signal.

[0138] A first implementation manner: the optical sending device modulates the detection sequence X into the first optical signal using a direct modulation manner.

[0139] Specifically, the optical transmitting device uses the detection sequence X to modulate a driving signal (e.g., a driving current) of a light source so that the light source emits a first optical signal carrying the detection sequence X. When the first optical signal also carries a data signal Y, the optical transmitting device may modulate the data signal Y into the first optical signal using a direct modulation method or an external modulation method.

[0140] In one example, a first optical signal carries a detection sequence X and does not carry a data signal Y. The optical transmitting device modulates the detection sequence X into the first optical signal using a direct modulation method. The optical transmitting device generates the first optical signal using a direct modulation method. Please refer to Figure 10, which shows a schematic diagram of an optical transmitting device generating a first optical signal provided by an embodiment of the present application. As shown in Figure 10, the optical transmitting device includes a light source, and the optical transmitting device modulates a driving signal of the light source using the detection sequence X so that the light source emits a first optical signal carrying the detection sequence X.

[0141] In another example, the first optical signal carries a detection sequence X and a data signal Y, and the optical transmitting device modulates the detection sequence X and the data signal Y into the first optical signal using a direct modulation method. The optical transmitting device generates a first optical signal carrying the detection sequence X and the data signal Y using a direct modulation method. Please refer to Figure 11, which shows another schematic diagram of the optical transmitting device provided in an embodiment of the present application generating a first optical signal. As shown in Figure 11, the optical transmitting device includes a light source, and the optical transmitting device sequentially uses the detection sequence X and the data signal Y to modulate the driving signal of the light source so that the light source emits a first optical signal carrying the detection sequence X and the data signal Y. Figure 11 illustrates an example in which the optical transmitting device first modulates the driving signal of the light source using the detection sequence X, and then modulates the driving signal of the light source using the data signal Y. In some embodiments, the optical transmitting device first modulates the driving signal of the light source using the data signal Y, and then modulates the driving signal of the light source using the detection sequence X. In other embodiments, as shown in FIG12 , the optical transmitting device modulates the detection sequence X onto the data signal Y. The optical transmitting device uses the data signal Y modulated with the detection sequence X to modulate the driving signal of the light source so that the light source emits a first optical signal carrying the detection sequence X and the data signal Y. This embodiment of the present application is not limited to this.

[0142] In another example, a first optical signal carries a detection sequence X and a data signal Y. The optical transmitting device modulates the detection sequence X into the first optical signal using a direct modulation method. The optical transmitting device modulates the data signal Y into the first optical signal using an external modulation method. The optical transmitting device generates a first optical signal carrying the detection sequence X and the data signal Y using direct modulation and external modulation methods. Please refer to Figure 13, which shows another schematic diagram of an optical transmitting device provided in an embodiment of the present application generating a first optical signal. As shown in Figure 13, the optical transmitting device includes a light source and a modulator. The optical transmitting device modulates a driving signal of the light source using the detection sequence X so that the light source emits a first optical signal carrying the detection sequence X. The first optical signal carrying the detection sequence X emitted by the light source is incident on the modulator. The modulator modulates the first optical signal carrying the detection sequence X using the data signal Y to obtain a first optical signal carrying the detection sequence X and the data signal Y.

[0143] Second implementation manner: the optical sending device modulates the detection sequence X into the first optical signal using external modulation.

[0144] Specifically, the optical transmitting device modulates the optical signal emitted by the light source using the detection sequence X to obtain a first optical signal carrying the detection sequence X. When the first optical signal also carries the data signal Y, the optical transmitting device may modulate the data signal Y into the first optical signal using direct modulation or external modulation.

[0145] In one example, a first optical signal carries a detection sequence X and does not carry a data signal Y. The optical transmitting device modulates the detection sequence X into the first optical signal using external modulation. The optical transmitting device generates the first optical signal using external modulation. Please refer to Figure 14, which shows another schematic diagram of an optical transmitting device generating a first optical signal provided by an embodiment of the present application. As shown in Figure 14, the optical transmitting device includes a light source and a modulator. The modulator modulates the optical signal emitted by the light source using the detection sequence X to obtain a first optical signal carrying the detection sequence X.

[0146] In another example, a first optical signal carries a detection sequence X and a data signal Y. The optical transmitting device modulates the detection sequence X and the data signal Y into the first optical signal using an external modulation method. The optical transmitting device generates a first optical signal carrying the detection sequence X and the data signal Y using an external modulation method. Please refer to Figure 15, which shows another schematic diagram of an optical transmitting device provided in an embodiment of the present application generating a first optical signal. As shown in Figure 15, the optical transmitting device includes a light source, a modulator 1, and a modulator 2. Modulator 1 modulates the optical signal emitted by the light source using the detection sequence X to obtain a first optical signal carrying the detection sequence X. The first optical signal modulated by modulator 1 is input to modulator 2. Modulator 2 modulates the first optical signal carrying the detection sequence X using the data signal Y to obtain a first optical signal carrying the detection sequence X and the data signal Y. That is, the optical transmitting device sequentially modulates the optical signal emitted by the light source using the detection sequence X and the data signal Y to obtain a first optical signal carrying the detection sequence X and the data signal Y. Figure 15 takes the example of the optical transmitting device first modulating the optical signal using the detection sequence X and then modulating the optical signal using the data signal Y. In some embodiments, the optical transmitting device first modulates the optical signal using the data signal Y and then modulates the optical signal using the detection sequence X. In other embodiments, as shown in FIG16 , the optical transmitting device modulates the detection sequence X onto the data signal Y. The optical transmitting device modulates the optical signal emitted by the light source using the data signal Y modulated with the detection sequence X to obtain a first optical signal carrying the detection sequence X and the data signal Y. This embodiment of the present application is not limited to this.

[0147] In another example, a first optical signal carries a detection sequence X and a data signal Y. The optical transmitting device modulates the data signal Y into the first optical signal using direct modulation. The optical transmitting device modulates the detection sequence X into the first optical signal using external modulation. The optical transmitting device generates a first optical signal carrying the detection sequence X and the data signal Y using direct modulation and external modulation. Please refer to FIG17 , which shows another schematic diagram of an optical transmitting device providing an embodiment of the present application generating a first optical signal. As shown in FIG17 , the optical transmitting device includes a light source and a modulator. The optical transmitting device modulates a driving signal of the light source using the data signal Y so that the light source emits a first optical signal carrying the data signal Y. The first optical signal carrying the data signal Y emitted by the light source is incident on the modulator. The modulator modulates the first optical signal carrying the data signal Y using the detection sequence X to obtain a first optical signal carrying the detection sequence X and the data signal Y.

[0148] In an optional embodiment, when the first optical signal carries the detection sequence X and the data signal Y, for the modulation schemes shown in Figures 11, 12, and 16, the first optical signal can be expressed using the following formula (5). For the modulation schemes shown in Figures 13, 15, and 17, the first optical signal can be expressed using the following formula (6).

[0149] P(t)=(P0(t)+C)*(1+m*Patt detect ) Formula (5).

[0150] P(t)=P0(t)+m*Patt detect Formula (6).

[0151] In the above equations (5) and (6), P0(t) represents the data signal Y, Patt detect represents the detection sequence X, m represents the ratio of the modulation depth of the detection sequence X to the modulation depth of the data signal Y (when the modulation depth of the data signal Y is 1, m represents the modulation depth of the detection sequence X), C is a constant DC bias, C is a constant, and the existence of C is to make P0(t)+C greater than 0. The symbol "*" represents the multiplication sign.

[0152] S302. The optical sending device sends a first optical signal through the optical fiber link Z.

[0153] For example, the optical transmitting device includes an interface corresponding to the optical fiber link Z, and the optical transmitting device sends the first optical signal through the interface to send the first optical signal through the optical fiber link Z. The interface is a physical (PHY) interface. For example, the interface is a gigabyte Ethernet (GE) interface (e.g., a 400GE interface), a terabit Ethernet (TE) interface, etc.

[0154] S303. The optical receiving device receives a second optical signal through the optical fiber link Z. The second optical signal includes the first optical signal and the reflected optical signal.

[0155] For example, the optical receiving device is the optical receiving device 220 in the optical fiber communication system shown in FIG. 2 , and the optical fiber link Z is the optical fiber link 230 .

[0156] For example, the optical receiving device includes an interface corresponding to the optical fiber link Z, and the optical receiving device receives the first optical signal through the interface to receive the first optical signal through the optical fiber link Z. The interface is a PHY interface. For example, the interface is a GE interface, a TE interface, etc.

[0157] S304. The optical receiving device demodulates the second optical signal to obtain a detection sequence X.

[0158] In an optional embodiment, the first optical signal carries multiple periodically distributed detection sequences X, and correspondingly, the second optical signal carries multiple periodically distributed detection sequences X. The optical receiving device demodulates the second optical signal to obtain the multiple detection sequences X.

[0159] In one embodiment, in the first optical signal, a boundary marker exists between adjacent detection sequences X among the multiple detection sequences X; therefore, in the second optical signal, a boundary marker exists between adjacent detection sequences X among the multiple detection sequences X. The optical receiving device determines the detection sequence X carried by the second optical signal based on the boundary marker carried by the second optical signal. In a specific embodiment, the optical receiving device searches for a boundary marker in the second optical signal; identifies the starting position and / or ending position of the detection sequence X carried by the second optical signal based on the found boundary marker; determines the detection sequence X based on the starting position and / or ending position of the detection sequence X; and can determine at least one detection sequence X from the second optical signal. For example, the optical receiving device identifies the starting position and ending position of the detection sequence X carried by the second optical signal based on the found boundary marker, and determines the portion between the starting position and the ending position of the detection sequence X as the detection sequence X. In another example, the optical receiving device identifies the starting position of the detection sequence X carried by the second optical signal based on the found boundary marker, and determines the portion between adjacent starting positions as a detection sequence X. For another example, the optical receiving device identifies the end position of the detection sequence X carried by the second optical signal based on the found boundary marker, and the optical receiving device determines the portion between adjacent end positions as a detection sequence X. In an optional embodiment, because the multiple detection sequences X are periodically distributed in the second optical signal, after the optical receiving device determines a detection sequence X carried by the second optical signal based on the found boundary marker, the optical receiving device determines other detection sequences X carried by the second optical signal based on the distribution period of the multiple detection sequences X. This embodiment of the present application is not limited to this.

[0160] In another embodiment, in the first optical signal, adjacent detection sequences X among the multiple detection sequences X are continuous, and no boundary markers exist between adjacent detection sequences X among the multiple detection sequences X; therefore, in the second optical signal, adjacent detection sequences X among the multiple detection sequences X are continuous. The optical receiving device determines the detection sequence X carried by the second optical signal based on the characteristics of the detection sequence X. The characteristics of the detection sequence X may be distribution characteristics, correlation characteristics (e.g., autocorrelation characteristics), etc. of the detection sequence X. In one implementation, the optical receiving device extracts a sequence (e.g., a randomly extracted sequence) from the second optical signal based on the length of the detection sequence X pre-acquired by the optical receiving device (e.g., a detection sequence X pre-negotiated between the optical transmitting device and the optical receiving device, a detection sequence X pre-configured in the optical receiving device, etc.). For ease of description, the sequence extracted from the second optical signal by the optical receiving device is referred to as a test sequence, and the length of the test sequence is equal to the length of the detection sequence X pre-acquired by the optical receiving device. The optical receiving device verifies whether the test sequence is the detection sequence X based on the detection sequence X pre-acquired by the optical receiving device. If the verification determines that the test sequence is the detection sequence X, the optical receiving device determines that a detection sequence X has been found in the second optical signal. The optical receiving device determines other detection sequences X carried by the second optical signal based on the distribution period of the multiple detection sequences X. If the verification determines that the test sequence is not the detection sequence X, the optical receiving device re-extracts the test sequence from the second optical signal and verifies whether the re-extracted test sequence is the detection sequence X, until the optical receiving device finds a detection sequence X in the second optical signal. In one example, the optical receiving device performs a correlation calculation on the test sequence and the pre-acquired detection sequence X, and determines whether the test sequence is the detection sequence X based on the correlation calculation result. In a specific embodiment, the optical receiving device performs a correlation calculation on the test sequence and the pre-acquired detection sequence X to obtain a cross-correlation curve between the test sequence and the pre-acquired detection sequence X. The optical receiving device compares the cross-correlation curve with the autocorrelation curve of the pre-acquired detection sequence X to determine whether the cross-correlation curve and the autocorrelation curve of the pre-acquired detection sequence X match. If the comparison determines that the cross-correlation curve and the autocorrelation curve of the pre-acquired detection sequence X match, the optical receiving device determines that the test sequence is the detection sequence X. If the comparison determines that the cross-correlation curve and the autocorrelation curve of the pre-acquired detection sequence X do not match, the optical receiving device determines that the test sequence is not the detection sequence X.In another example, the optical receiving device compares the test sequence with the pre-acquired detection sequence X to determine whether the test sequence matches the pre-acquired detection sequence X. If the comparison determines that the test sequence matches the pre-acquired detection sequence X, the optical receiving device determines that the test sequence is the detection sequence X. If the comparison determines that the test sequence does not match the pre-acquired detection sequence X, the optical receiving device determines that the test sequence is not the detection sequence X. It should be noted that the match described in this paragraph includes but is not limited to being substantially identical or completely identical, and substantially identical means being essentially identical but with minor differences. For example, for ease of description, the cross-correlation curve between the sequence to be tested and the pre-acquired detection sequence X is referred to as a cross-correlation curve Q1, and the autocorrelation curve of the pre-acquired detection sequence X is referred to as an autocorrelation curve Q2. The cross-correlation curve Q1 is substantially identical to the autocorrelation curve Q2, including that the number of time-shifted symbols at each position point on the cross-correlation curve Q1 is the same as the number of time-shifted symbols at the corresponding position point on the autocorrelation curve Q2, and the correlation value at each position point on the cross-correlation curve Q1 is substantially identical to the correlation value at the corresponding position point on the autocorrelation curve Q2 (for example, the correlation values ​​are equal, or the difference in the correlation values ​​is less than a threshold). For example, the cross-correlation curve Q1 and the autocorrelation curve Q2 include position points -m to m, respectively. The correlation value of position point -m on the cross-correlation curve Q1 is substantially the same as the correlation value of position point -m on the autocorrelation curve Q2. The correlation value of position point -m+1 on the cross-correlation curve Q1 is substantially the same as the correlation value of position point -m+1 on the autocorrelation curve Q2. The correlation value of position point -m+2 on the cross-correlation curve Q1 is substantially the same as the correlation value of position point -m+2 on the autocorrelation curve Q2, and so on. For another example, the matching of the test sequence with the pre-acquired detection sequence X includes a one-to-one correspondence between multiple symbols of the test sequence and multiple symbols of the pre-acquired detection sequence X, and the amplitudes of the symbols of the test sequence are substantially the same as the amplitudes of corresponding symbols of the pre-acquired detection sequence X (for example, the amplitudes are equal, or the difference in amplitudes is less than a threshold). For example, the pre-acquired detection sequence X is 1,1,1,-1,1,1,-1,1,1,1,-1,-1,-1,-1,1,-1, and the sequence to be verified is 1,1,1,-1.2,1,1,-1,1,1.3,1,1,-1,-1,-1,-1,1, then the sequence to be verified matches the pre-acquired detection sequence X.

[0161] In an optional embodiment, the optical receiving device converts the second optical signal into an electrical signal, and the optical receiving device performs demodulation based on the electrical signal to obtain a detection sequence X. In a specific embodiment, the optical receiving device performs photoelectric conversion on the second optical signal to obtain a first electrical signal, which is an analog electrical signal; the optical receiving device converts the first electrical signal into a digital electrical signal (for ease of description, the digital electrical signal is referred to as the second electrical signal); and the optical receiving device determines the detection sequence X based on the second electrical signal. In one embodiment, the second optical signal carries multiple detection sequences X distributed periodically, and boundary markers exist between adjacent detection sequences X in the multiple detection sequences X. Therefore, the second electrical signal includes multiple detection sequences X distributed periodically, and boundary markers exist between adjacent detection sequences X in the multiple detection sequences X. The optical receiving device searches for the boundary marker in the second electrical signal, identifies the starting position and / or ending position of the detection sequence X in the second electrical signal based on the found boundary marker, and determines the detection sequence X based on the starting position and / or ending position of the detection sequence X. The optical receiving device can determine at least one detection sequence X from the second electrical signal. In another embodiment, the second optical signal carries multiple periodically distributed detection sequences X, where no boundary markers exist between adjacent detection sequences X in the multiple detection sequences X. Therefore, the second electrical signal includes multiple periodically distributed detection sequences X, where no boundary markers exist between adjacent detection sequences X in the multiple detection sequences X. The optical receiving device determines at least one detection sequence X from the second electrical signal based on the characteristics of the detection sequence X. Optionally, because the second electrical signal typically contains noise, before determining the detection sequence X from the second electrical signal, the optical receiving device performs noise reduction processing, equalization processing, etc. on the second electrical signal to reduce the impact of noise on the second electrical signal. The optical receiving device determines the detection sequence X from the second electrical signal after the noise reduction and equalization processing, thereby preventing noise from affecting the optical receiving device's determination of the detection sequence X from the second electrical signal. In this embodiment of the present application, the process of the optical receiving device determining the detection sequence X from the second electrical signal can be referred to as a synchronization process. For example, the optical receiving device includes a synchronization unit, which determines the detection sequence X from the second electrical signal. This embodiment of the present application is not limited to this.

[0162] In an optional embodiment, the first optical signal also carries a data signal Y. That is, the first optical signal carries a detection sequence X and a data signal Y. For example, the first optical signal carries the data signal Y and a plurality of periodically distributed detection sequences X. Correspondingly, the second optical signal also carries the data signal Y. The optical receiving device demodulating the second optical signal further includes: the optical receiving device filtering the second optical signal to obtain a detection signal, and the detection signal includes the detection sequence X. For example, the detection signal includes a plurality of periodically distributed detection sequences X. In the case where the second optical signal also carries a boundary identifier, the detection signal also includes a boundary identifier. The detection signal includes noise, and a portion of the noise in the detection signal may be the data signal Y. In a specific embodiment, the optical receiving device performs photoelectric conversion on the second optical signal to obtain a first electrical signal; the optical receiving device converts the first electrical signal into a digital electrical signal (i.e., a second electrical signal); the optical receiving device filters the second electrical signal to obtain a filtered second electrical signal, and the filtered second electrical signal is the detection signal, and the optical receiving device determines the detection sequence X based on the filtered second electrical signal. In another specific implementation, the optical receiving device performs photoelectric conversion on the second optical signal to obtain a first electrical signal; the optical receiving device filters the first electrical signal to obtain a filtered first electrical signal; the optical receiving device converts the filtered first electrical signal into a digital electrical signal (i.e., a second electrical signal), the second electrical signal being the detection signal, and the optical receiving device determines a detection sequence X based on the second electrical signal. The optical receiving device uses an analog filter to filter the first electrical signal, and the optical receiving device uses a digital filter to filter the second electrical signal. For example, in the first optical signal, the modulation depth of the detection sequence X is less than the modulation depth of the data signal Y, and the baud rate of the detection sequence X is less than the baud rate of the data signal Y. The filter is a low-pass filter.

[0163] S305. The optical receiving device determines the transmission performance of the optical fiber link Z based on the detection sequence X demodulated from the second optical signal.

[0164] It should be noted that, in the case where the first optical signal carries multiple detection sequences X, the second optical signal also carries multiple detection sequences X. In S304, the optical receiving device can demodulate at least one detection sequence X from the second optical signal. In S305, the optical receiving device can determine the transmission performance of the optical fiber link Z based on one or more detection sequences X in the at least one detection sequence X. For example, in order to ensure the reliability of the detection result, the optical receiving device determines the transmission performance of the optical fiber link Z based on the multiple detection sequences X demodulated from the second optical signal. The implementation process of the optical receiving device determining the transmission performance of the optical fiber link Z based on any two detection sequences X in the multiple detection sequences X is the same. The following is an example of the optical receiving device determining the transmission performance of the optical fiber link Z based on a detection sequence X demodulated from the second optical signal. The implementation process of the optical receiving device determining the transmission performance of the optical fiber link Z based on each detection sequence X demodulated from the second optical signal can be referred to the description below.

[0165] In an embodiment of the present application, the autocorrelation curve corresponding to the detection sequence X modulated by the optical transmitting device on the first optical signal meets a preset condition, so the optical receiving device can determine the transmission performance of the optical fiber link Z based on whether the correlation curve corresponding to the detection sequence X demodulated from the second optical signal meets the preset condition. The correlation curve can be an autocorrelation curve or a cross-correlation curve. The autocorrelation curve corresponding to the demodulated detection sequence X is determined based on the demodulated detection sequence X. The cross-correlation curve corresponding to the demodulated detection sequence X is determined based on the demodulated detection sequence and the detection sequence X pre-acquired by the optical receiving device. The detection sequence X pre-acquired by the optical receiving device is the detection sequence X modulated by the optical transmitting device on the first optical signal pre-acquired by the optical receiving device. The detection sequence X pre-acquired by the optical receiving device can be pre-negotiated between the optical transmitting device and the optical receiving device, or can be pre-configured in the optical receiving device. The cross-correlation curve determined based on the demodulated detection sequence X and the pre-acquired detection sequence X can also be considered as the autocorrelation curve of the detection sequence X.

[0166] In a specific embodiment, the optical receiving device obtains a correlation curve (autocorrelation curve or cross-correlation curve) corresponding to the detection sequence X demodulated from the second optical signal. The optical receiving device determines whether the correlation curve (autocorrelation curve or cross-correlation curve) satisfies the preset condition. If the optical receiving device determines that the correlation curve satisfies the preset condition, the optical receiving device determines that the optical fiber link Z is fault-free. If the optical receiving device determines that the correlation curve does not satisfy the preset condition, the optical receiving device determines that a fault exists in the optical fiber link Z.

[0167] In an optional embodiment, the autocorrelation curve corresponding to the detection sequence X modulated by the optical transmitting device on the first optical signal satisfies a preset condition, including the autocorrelation curve corresponding to the detection sequence X having a characteristic peak. The optical receiving device determines the transmission performance of the optical fiber link Z based on the characteristic peak of the correlation curve (autocorrelation curve or cross-correlation curve) corresponding to the detection sequence X demodulated from the second optical signal. In a specific embodiment, the optical receiving device determines whether the optical fiber link Z is faulty based on the characteristic peak of the correlation curve corresponding to the detection sequence X demodulated from the second optical signal. In one embodiment, the correlation curve corresponding to the detection sequence X modulated by the optical transmitting device on the first optical signal satisfies a preset condition, including the autocorrelation curve corresponding to the detection sequence X having only one characteristic peak, and the autocorrelation values ​​of all positions on the autocorrelation curve corresponding to the detection sequence X other than the characteristic peak are all zero. The optical receiving device determines the number of characteristic peaks of the correlation curve corresponding to the detection sequence X demodulated from the second optical signal. If the optical receiving device determines that the correlation curve corresponding to the detection sequence X demodulated from the second optical signal has only one characteristic peak, the optical receiving device determines that the optical fiber link Z is fault-free. When the optical receiving device determines that the correlation curve corresponding to the detection sequence X demodulated from the second optical signal has multiple characteristic peaks, the optical receiving device determines that a fault exists in the optical fiber link.

[0168] In an optional embodiment, when the optical receiving device determines that the correlation curve corresponding to the detection sequence X demodulated from the second optical signal has multiple characteristic peaks, the optical receiving device determines the fault point on the optical fiber link Z based on the main peak among the multiple characteristic peaks and the secondary peaks among the multiple characteristic peaks. The multiple characteristic peaks include a main peak and at least one secondary peak, and the peak value of the at least one secondary peak is smaller than the peak value of the main peak. Each of the at least one secondary peak corresponds to two reflection points on the optical fiber link Z, and at least one of the two reflection points is a fault point. In addition, the partial reflection points corresponding to different secondary peaks can be the same or different. For example, secondary peak 1 corresponds to reflection point 1 and reflection point 2, and secondary peak 2 corresponds to reflection point 1 and reflection point 3, then the partial reflection points corresponding to secondary peak 1 and secondary peak 2 are the same.

[0169] In a specific embodiment, the horizontal axis of the correlation curve corresponding to the detection sequence X demodulated from the second optical signal represents the number of time-shifted symbols. When the correlation curve includes a main peak and at least one secondary peak, for each of the at least one secondary peak, the optical receiving device determines the difference between the number of time-shifted symbols corresponding to the secondary peak and the number of time-shifted symbols corresponding to the main peak (for ease of description, the difference is referred to as the time-shifted symbol difference corresponding to the secondary peak); the optical receiving device determines the transmission duration of the reflected signal between the two reflection points corresponding to the secondary peak based on the time-shifted symbol difference corresponding to the secondary peak and the baud rate at which the optical transmitting device modulates the detection sequence X on the first optical signal; the optical receiving device determines the distance between the two reflection points corresponding to the secondary peak on the optical fiber link Z based on the transmission duration, and further determines the fault point on the optical fiber link Z based on the distance between the two reflection points. For example, if the end face of the connector in the optical fiber link is dirty or the connector is loose, resulting in poor contact, it will cause a large reflection of the optical signal at the connector. The reflection point on the optical fiber link Z is usually located at the location of the connector. The optical receiving device can determine the fault point on the optical fiber link Z based on the distance between the two reflection points corresponding to the secondary peak and the deployment of the optical fiber link Z.

[0170] The time-shift symbol difference corresponding to the secondary peak may be a positive value or a negative value. A positive value indicates that the detection sequence of the current cycle is reflected by the reflection point corresponding to the secondary peak, and a negative value indicates that the detection sequence of the previous cycle is reflected by the reflection point corresponding to the secondary peak and is delayed to the detection sequence of the current cycle. When the time-shift symbol difference corresponding to the secondary peak is a positive value, the optical receiving device determines the product of the time-shift symbol difference corresponding to the secondary peak and the symbol period (i.e., the inverse of the baud rate) of the detection sequence X modulated on the first optical signal by the optical transmitting device as the transmission duration of the reflected signal between the two reflection points corresponding to the secondary peak. When the time-shifted sign difference corresponding to the secondary peak is a negative value, the optical receiving device determines the sum of the time-shifted sign difference corresponding to the secondary peak and the length of the target sequence. The optical receiving device determines the sum of the time-shifted sign difference corresponding to the secondary peak and the length of the target sequence as the number of delayed symbols corresponding to the secondary peak. The optical receiving device determines the product of the number of delayed symbols corresponding to the secondary peak and the symbol period (i.e., the inverse of the baud rate) at which the optical transmitting device modulates the detection sequence X onto the first optical signal as the transmission duration of the reflected signal between the two reflection points corresponding to the secondary peak. The target sequence is the sequence used in the process of obtaining the correlation curve corresponding to the demodulated detection sequence X, and the target sequence can be the first sequence, the second sequence, or the detection sequence X.

[0171] For example, for each of the at least one secondary peak, the optical receiving device determines the distance between the two reflection points corresponding to the secondary peak on the optical fiber link Z using a distance-time formula based on the transmission time of the reflected signal between the two reflection points corresponding to the secondary peak. For example, the distance-time formula is D = v*T / 2, where v represents the transmission speed of the first optical signal in the optical fiber link Z, T represents the transmission time of the reflected signal between the two reflection points corresponding to the secondary peak, and D represents the distance between the two reflection points corresponding to the secondary peak. The symbol "*" represents a multiplication sign, and the symbol " / " represents a division sign. In an optional embodiment, the end face of the laser of the optical transmitting device has a strong reflective ability, and the end face of the laser of the optical transmitting device can be considered as a fixed reflection point. In this case, the "D" in the distance-time formula represents the distance between a fault point in the optical fiber link Z (the fault point corresponding to the secondary peak) and the optical transmitting device (specifically, the distance between the fault point corresponding to the secondary peak and the end face of the laser of the optical transmitting device). The optical receiving device determines the distance between the two reflection points corresponding to the secondary peak, and thus determines the distance between the fault point corresponding to the secondary peak and the end face of the laser of the optical transmitting device, that is, determines the position of the fault point corresponding to the secondary peak.

[0172] As an example, please refer to FIG18 , which shows a schematic diagram of a correlation curve corresponding to the detection sequence X demodulated from the second optical signal by the optical receiving device. The correlation curve can be an autocorrelation curve corresponding to the detection sequence X demodulated from the second optical signal, or a cross-correlation curve determined based on the detection sequence X demodulated from the second optical signal and the detection sequence X pre-acquired by the optical receiving device. Referring to FIG18 , the correlation curve has two characteristic peaks, and the correlation values ​​of each position point on the correlation curve other than the two characteristic peaks are all 0 ( FIG18 is only an example. In actual applications, due to the influence of random noise, the autocorrelation values ​​of each position point on the correlation curve other than the characteristic peaks are all very low noise floors, that is, the correlation values ​​of each position point on the correlation curve other than the characteristic peaks are very small but may not be 0). Assuming that it is known that the end face of the laser of the optical transmitting device has a strong reflectivity and is a fixed reflection point, the optical receiving device determines that there is a fault in the optical fiber link Z based on the characteristic peaks of the correlation curve. Furthermore, the two characteristic peaks include a main peak and a secondary peak. The number of time-shifted symbols corresponding to the main peak is 0, and the number of time-shifted symbols corresponding to the secondary peak is 2. Therefore, the optical receiving device determines that the time-shifted symbol difference corresponding to the secondary peak is 2 (2-0=2). The optical receiving device determines the product of the time-shifted symbol difference corresponding to the secondary peak and the symbol period of the optical transmitting device modulating the detection sequence X on the first optical signal as the transmission time length of the reflected signal between the two reflection points corresponding to the secondary peak (the end face of the laser of the optical transmitting device and a fault point). Based on the transmission time length, the optical receiving device uses the above-mentioned distance-time formula to determine the distance between the two reflection points corresponding to the secondary peak. Furthermore, based on the distance between the two reflection points and the known position of the end face of the laser of the optical transmitting device, the optical receiving device determines the fault point on the optical fiber link Z corresponding to the secondary peak.

[0173] In an optional embodiment, when the optical receiving device determines that the correlation curve corresponding to the detection sequence X demodulated from the second optical signal has multiple characteristic peaks, the optical receiving device also determines the strength of the reflection degree of the reflection point (including the fault point) corresponding to the secondary peak based on the amplitude of each secondary peak in the multiple characteristic peaks. For example, the vertical axis of the correlation curve corresponding to the detection sequence X represents the correlation (i.e., the correlation value), and the amplitude of each secondary peak is used to reflect the strength of the reflection degree of the reflection point (including the fault point) corresponding to the secondary peak. The amplitude of the secondary peak is positively correlated with the strength of the reflection degree of the reflection point corresponding to the secondary peak. The larger the amplitude of the secondary peak, the stronger the reflection degree of the reflection point (including the fault point) corresponding to the secondary peak. The smaller the amplitude of the secondary peak, the weaker the reflection degree of the reflection point (including the fault point) corresponding to the secondary peak. The strength of the reflection degree is also called reflection intensity.

[0174] In the embodiment of the present application, the optical receiving device can not only determine whether there is a fault in the optical fiber link Z based on the correlation curve corresponding to the detection sequence X demodulated from the second optical signal, but also, when it is determined that there is a fault in the optical fiber link Z, the optical receiving device can also determine the fault point on the optical fiber link Z based on the characteristic peak of the correlation curve, thereby locating the fault in the optical fiber link Z. Therefore, in the embodiment of the present application, when locating the fault, there is no need for staff to carry instruments to the station for positioning, and the implementation process is simple. In addition, when it is determined that there is a fault in the optical fiber link Z, the optical receiving device can also determine the strength of the reflection degree of the reflection point (including the fault point) corresponding to the secondary peak based on the amplitude of the secondary peak of the correlation curve, thereby qualitatively determining the magnitude of the fault degree of the fault point.

[0175] In an optional embodiment, the correlation curve corresponding to the detection sequence X demodulated from the second optical signal may be an autocorrelation curve or a cross-correlation curve. The autocorrelation curve corresponding to the demodulated detection sequence X is determined based on the demodulated detection sequence X. The cross-correlation curve corresponding to the demodulated detection sequence X is determined based on the demodulated detection sequence and a detection sequence X pre-acquired by the optical receiving device. The detection sequence X pre-acquired by the optical receiving device is the detection sequence X modulated by the optical transmitting device onto the second optical signal and pre-acquired by the optical receiving device.

[0176] In one embodiment, the correlation curve corresponding to the detection sequence X demodulated from the second optical signal is an autocorrelation curve, and the optical receiving device determines the autocorrelation curve based on the demodulated detection sequence X. In a specific embodiment, the detection sequence X modulated by the optical transmitting device on the first optical signal is a Golay complementary sequence or a pseudorandom code sequence, and the detection sequence X includes a first sequence A and a second sequence B. After the optical receiving device demodulates the detection sequence X from the second optical signal, the optical receiving device determines the first sequence A and the second sequence B from the demodulated detection sequence X. The optical receiving device determines the autocorrelation curve corresponding to the demodulated detection sequence X based on the first sequence A and the second sequence B determined from the demodulated detection sequence X. For example, in the detection sequence X, the second sequence B is located after the first sequence A and is adjacent to the first sequence A. The lengths of the first sequence A and the second sequence B are both fixed. For example, the length of the first sequence A is a first length, and the length of the second sequence B is a second length. The optical receiving device determines a sequence of a first length starting from the start position of the demodulated detection sequence X as a first sequence A, and determines the sequence in the demodulated detection sequence X other than the first sequence A as a second sequence B. It should be noted that the first sequence A mentioned in the subsequent description of this paragraph refers to the first sequence A determined from the demodulated detection sequence X, and the second sequence B mentioned in the subsequent description of this paragraph refers to the second sequence B determined from the demodulated detection sequence X. In one embodiment, the optical receiving device performs an autocorrelation calculation on the first sequence A to obtain an autocorrelation curve of the first sequence A; the optical receiving device performs an autocorrelation calculation on the second sequence B to obtain an autocorrelation curve of the second sequence B; and the optical receiving device determines an autocorrelation curve corresponding to the demodulated detection sequence X based on the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B. In a specific embodiment, the position points on the autocorrelation curve of the first sequence A correspond one-to-one with the position points on the autocorrelation curve of the second sequence B. The optical receiving device adds the amplitudes on the autocorrelation curve of the first sequence A and the amplitudes on the autocorrelation curve of the second sequence B according to the position points. The optical receiving device draws a curve based on the added amplitudes to obtain the demodulated autocorrelation curve corresponding to the detection sequence X. In one example, the autocorrelation curve of the first sequence A and the autocorrelation curve of the second sequence B both include position points -m to m, where m is a positive integer. The position points -m to m on the autocorrelation curve of the first sequence A correspond one-to-one with the position points -m to m on the autocorrelation curve of the second sequence B. The optical receiving device adds the amplitude corresponding to the position point -m on the autocorrelation curve of the first sequence A and the amplitude corresponding to the position point -m on the autocorrelation curve of the second sequence B to obtain the superimposed amplitude corresponding to the position point -m.The optical receiving device adds the amplitude corresponding to the position point -m+1 on the autocorrelation curve of the first sequence A and the amplitude corresponding to the position point -m+1 on the autocorrelation curve of the second sequence B to obtain the superimposed amplitude corresponding to the position point -m+1. The optical receiving device adds the amplitude corresponding to the position point -m+2 on the autocorrelation curve of the first sequence A and the amplitude corresponding to the position point -m+2 on the autocorrelation curve of the second sequence B to obtain the superimposed amplitude corresponding to the position point -m+2. By analogy, the optical receiving device can determine the superimposed amplitudes corresponding to the positions -m~m. The optical receiving device draws a curve based on the position points -m~m and the superimposed amplitudes corresponding to the position points -m~m. The curve drawn by the optical receiving device is the autocorrelation curve corresponding to the detection sequence X demodulated from the second optical signal. For this embodiment, the target sequence described in the above embodiment can be the first sequence A or the second sequence B.

[0177] In another embodiment, the correlation curve corresponding to the detection sequence X demodulated from the second optical signal is a cross-correlation curve. The optical receiving device determines the cross-correlation curve based on the demodulated detection sequence X and the detection sequence X pre-acquired by the optical receiving device. In a specific embodiment, the detection sequence X modulated by the optical transmitting device on the first optical signal is a Gray complementary sequence or a pseudo-random code sequence, and the detection sequence X includes a first sequence A and a second sequence B. After the optical receiving device demodulates the detection sequence X from the second optical signal, the optical receiving device determines the first sequence A and the second sequence B from the demodulated detection sequence X, and the optical receiving device determines the first sequence and the second sequence from the pre-acquired detection sequence X. For ease of description, the first sequence determined by the optical receiving device from the pre-acquired detection sequence X is referred to as the first sequence A', and the second sequence determined by the optical receiving device from the pre-acquired detection sequence X is referred to as the second sequence B'. The optical receiving device determines a cross-correlation curve corresponding to the demodulated detection sequence X based on the first sequence A and the second sequence B determined from the demodulated detection sequence X, and based on the first sequence A' and the second sequence B' determined from the pre-acquired detection sequence X. For example, in the detection sequence X, the second sequence B is located after the first sequence A and is adjacent to the first sequence A. The lengths of the first sequence A and the second sequence B are both fixed, for example, the length of the first sequence A is a first length, and the length of the second sequence B is a second length. The optical receiving device determines a sequence of the first length starting from the starting position of the demodulated detection sequence X as the first sequence A, and determines sequences in the demodulated detection sequence X other than the first sequence A as the second sequence B. The optical receiving device determines a sequence of the first length starting from the starting position of the pre-acquired detection sequence X as the first sequence A', and determines sequences in the pre-acquired detection sequence X other than the first sequence A' as the second sequence B'. It should be noted that the first sequence A mentioned in the subsequent description of this paragraph refers to the first sequence A determined from the demodulated detection sequence X, and the second sequence B mentioned in the subsequent description of this paragraph refers to the second sequence B determined from the demodulated detection sequence X. In one embodiment, the optical receiving device performs a cross-correlation calculation on the first sequence A and the first sequence A' to obtain a cross-correlation curve between the first sequence A and the first sequence A'; the optical receiving device performs a cross-correlation calculation on the second sequence B and the second sequence B' to obtain a cross-correlation curve between the second sequence B and the second sequence B'; and the optical receiving device determines a cross-correlation curve corresponding to the demodulated detection sequence X based on the cross-correlation curve between the first sequence A and the first sequence A' and the cross-correlation curve between the second sequence B and the second sequence B'.For example, the cross-correlation curves of the first sequence A and the first sequence A' are referred to as cross-correlation curve 1, and the cross-correlation curves of the second sequence B and the second sequence B' are referred to as cross-correlation curve 2. The cross-correlation curve corresponding to the demodulated detection sequence X is the superposition curve of cross-correlation curve 1 and cross-correlation curve 2. In a specific embodiment, the positions on cross-correlation curve 1 correspond to the positions on cross-correlation curve 2 in a one-to-one manner. The optical receiving device adds the amplitudes on cross-correlation curve 1 and the amplitudes on cross-correlation curve 2 according to the corresponding positions. The optical receiving device plots a curve based on the added amplitudes to obtain the demodulated cross-correlation curve corresponding to the detection sequence X. In one example, cross-correlation curve 1 and cross-correlation curve 2 both include positions -m to m, where m is a positive integer. Positions -m to m on cross-correlation curve 1 correspond to positions -m to m on cross-correlation curve 2 in a one-to-one manner. The optical receiving device adds the amplitude corresponding to position -m on cross-correlation curve 1 and the amplitude corresponding to position -m on cross-correlation curve 2 to obtain the superposition amplitude corresponding to position -m. The optical receiving device adds the amplitude corresponding to the position point -m+1 on the cross-correlation curve 1 and the amplitude corresponding to the position point -m+1 on the cross-correlation curve 2 to obtain the superimposed amplitude corresponding to the position point -m+1. The optical receiving device adds the amplitude corresponding to the position point -m+2 on the cross-correlation curve and the amplitude corresponding to the position point -m+2 on the cross-correlation curve 2 to obtain the superimposed amplitude corresponding to the position point -m+2. By analogy, the optical receiving device can determine the superimposed amplitudes corresponding to the position points -m~m. The optical receiving device draws a curve based on the position points -m~m and the superimposed amplitudes corresponding to the position points -m~m. The curve drawn by the optical receiving device is the cross-correlation curve corresponding to the demodulated detection sequence X. For this embodiment, the target sequence described in the above embodiment can be the first sequence A, the second sequence B, the first sequence A' or the second sequence B'.

[0178] In yet another embodiment, the correlation curve corresponding to the detection sequence X demodulated from the second optical signal is an autocorrelation curve of the demodulated detection sequence X. The detection sequence X may be a pseudorandom code sequence. After the optical receiving device demodulates the detection sequence X from the second optical signal, the optical receiving device performs an autocorrelation calculation on the demodulated detection sequence X to obtain an autocorrelation curve of the demodulated detection sequence X. In this embodiment, the target sequence described in the aforementioned embodiment may be the demodulated detection sequence X.

[0179] In another embodiment, the correlation curve corresponding to the detection sequence X demodulated from the second optical signal is a cross-correlation curve between the demodulated detection sequence X and a pre-acquired detection sequence X. The detection sequence X may be a pseudo-random code sequence. After the optical receiving device demodulates the detection sequence X from the second optical signal, the optical receiving device performs a cross-correlation calculation on the demodulated detection sequence X and the pre-acquired detection sequence X to obtain a cross-correlation curve between the demodulated detection sequence X and the pre-acquired detection sequence X. In this embodiment, the target sequence described in the aforementioned embodiment may be the demodulated detection sequence X or the pre-acquired detection sequence X.

[0180] To facilitate understanding of the implementation process of S305, the implementation principle of S305 is introduced below.

[0181] For example, the first optical signal carries multiple detection sequences X, the multiple detection sequences X are periodically distributed, and each detection sequence X in the multiple detection sequences X includes a first sequence A and a second sequence B, the second sequence B is located after the first sequence A and the second sequence B is adjacent to the first sequence A. For ease of description, an optical transmitting device is used to modulate the first optical signal using a detection signal as an example. The detection signal includes multiple detection sequences X, for example, the detection signal is composed of the multiple detection sequences X. For example, the detection signal modulated by the optical transmitting device on the first optical signal is Patt detect- Tx=[ABABAB……]. Patt detect- Tx represents the detection signal modulated by the optical transmitting device on the first optical signal, "A" represents the first sequence A, and "B" represents the second sequence B. Without considering the attenuation and failure of the optical fiber link Z, the detection signal obtained by the optical receiving device by demodulating the second optical signal is Patt detect- Rx=[ABABAB……]. Patt detect- Rx represents the detection signal obtained by demodulating the second optical signal by the optical receiving device. Therefore, without considering attenuation and faults of the optical fiber link Z, the detection signal obtained by demodulating the second optical signal by the optical receiving device is identical to the detection signal modulated by the optical transmitting device on the second optical signal.

[0182] However, the optical fiber link Z inevitably has attenuation and failure, and the detection signal obtained by the optical receiving device after demodulating the second optical signal includes noise caused by reflection at the reflection point (i.e., reflected optical signal). The reflected optical signal can be expressed as Data_Per = β*Patt detect-Tx(t-t0). Data_Per represents the reflected light signal, t0 represents the delay time of the reflected light signal compared to the detection signal, and β represents the attenuation coefficient of the reflected light signal (the reflection point in the optical fiber link Z reflects the detection signal multiple times, resulting in the formation of the reflected light signal, and β is the attenuation coefficient caused by the multiple reflections). If there are multiple reflection points in the optical fiber link Z, there will be multiple items on the right side of the above expression of the reflected light signal. Each item represents a different delay time of the reflected light signal compared to the detection signal, and the attenuation coefficient may also be different. Therefore, the detection signal actually obtained by the optical receiving device after demodulating the second optical signal is Patt detect- Rx=Patt detect- Tx+Data_Per.

[0183] In an embodiment of the present application, the optical receiving device determines a detection sequence X from the demodulated detection signal, and the optical receiving device obtains a correlation curve corresponding to the demodulated detection sequence X. When the demodulated detection sequence X does not include noise, the correlation curve corresponding to the demodulated detection sequence X can be an autocorrelation curve as shown in FIG7 , and the correlation curve has a characteristic peak, and the amplitudes of all position points on the correlation curve except the characteristic peak are 0. However, when the demodulated detection sequence X includes noise caused by reflection at a reflection point, the correlation curve corresponding to the demodulated detection sequence X can be as shown in FIG18 , and the correlation curve not only has a characteristic peak (main peak) similar to that shown in FIG7 , but also has a secondary peak. This secondary peak is generated by the superposition of the autocorrelation of the first half (corresponding to the first sequence A) and the autocorrelation of the second half (corresponding to the second sequence B) of the reflected optical signal Data_Per, or the superposition of the cross-correlation of the first half (corresponding to the first sequence A) of Data_Per with the first half (corresponding to the first sequence A') of the pre-acquired detection sequence X, and the cross-correlation of the second half (corresponding to the second sequence B) of Data_Per with the first half (corresponding to the second sequence B') of the pre-acquired detection sequence X. Therefore, the transmission time of the reflected signal between the two reflection points corresponding to the secondary peak can be determined based on the difference between the number of time-shifted symbols corresponding to the main peak and the number of time-shifted symbols corresponding to the secondary peak. Furthermore, based on this transmission time, the reflection point (fault point) corresponding to the secondary peak on the optical fiber link Z can be determined to achieve fault location.

[0184] In an optional embodiment, after the optical receiving device determines the transmission performance of the optical fiber link based on the detection sequence X demodulated from the second optical signal, for example, after the optical receiving device determines that the optical fiber link has a fault, the optical receiving device can issue a fault warning. In one example, the optical receiving device controls the indicator light of the optical receiving device to flash, emit light, etc. to issue a fault warning. In another example, the optical receiving device outputs a warning message to a device having a display component and / or a voice broadcast component to issue a fault warning. The device having a display component and / or a voice broadcast component can present the warning message through a display or voice broadcast to issue a fault warning, which is not limited in this embodiment of the present application.

[0185] It should be noted that both the optical transmitting device and the optical receiving device may include an optical module and / or a fiber optic card. In the description of the embodiment shown in FIG3 , all or part of the operations performed by the optical transmitting device are performed by the optical module and / or fiber optic card in the optical transmitting device, and all or part of the operations performed by the optical receiving device are performed by the optical module and / or fiber optic card in the optical receiving device. For example, the optical transmitting device includes an optical module or a fiber optic card, and the light source, modulator, etc. are all located on the optical module or fiber optic card. The optical receiving device includes an optical module or a fiber optic card, and the filter is located on the optical module or fiber optic card.

[0186] In summary, the optical fiber link detection method provided by the embodiment of the present application is that the optical transmitting device sends an optical signal carrying a detection sequence to the optical receiving device through the optical fiber link, and the optical receiving device determines the transmission performance of the optical fiber link according to the detection sequence carried by the optical signal received through the optical fiber link, thereby realizing the detection of the optical fiber link. It can be seen that the embodiment of the present application provides a transmission detection solution, which uses the existing optical transmitting device and optical receiving device of the optical fiber communication system to detect the transmission performance of the optical fiber link. There is no need to deploy additional equipment such as OTDR, circulator (or power splitter) in the optical fiber link, and there is no need to plug and unplug the optical fiber to realize the detection of the optical fiber link. Therefore, the hardware implementation of the optical fiber link detection is simple, the detection cost is low, and on-line detection can be realized, and fault location can be realized. When locating the fault, there is no need for staff to carry instruments to the station for positioning, the implementation process is simple, and the labor cost of detection is low.

[0187] Based on the description of the above embodiments, it can be seen that the embodiments of the present application can use an in-band detection method to detect the transmission performance of the optical fiber link, and can also use an out-of-band detection method to detect the transmission performance of the optical fiber link. The in-band detection method is also called the on-band detection method, which refers to carrying the detection sequence and the data signal in the same optical signal and sending it through the optical fiber link to detect the transmission performance of the optical fiber link based on the detection sequence. The out-of-band detection method refers to carrying the detection sequence in an independent optical signal and sending it through the optical fiber link to detect the transmission performance of the optical fiber link based on the detection sequence, that is, the detection sequence and the data signal are carried in different optical signals. In an optional embodiment, the optical transmitting device includes a switch unit, which is used to switch the data signal and the detection sequence, so that the optical transmitting device uses the detection sequence or the data signal to modulate the optical signal. For example, in the detection mode, the optical transmitting device uses the detection sequence to modulate the optical signal; in the non-detection mode, the optical transmitting device uses the data signal to modulate the optical signal. The optical receiving device may also include a switch unit, which is used to switch the data signal and the detection sequence, so that the optical receiving device demodulates the detection sequence or the data signal from the optical signal. For example, in detection mode, the optical receiving device demodulates a detection sequence from the optical signal; in non-detection mode, the optical receiving device demodulates a data signal from the optical signal. The operation of the switch unit can be controlled by a control device, which can be connected to both the optical transmitting device and the optical receiving device, although this is not limited in this embodiment of the present application.

[0188] To facilitate understanding of the technical solutions of the embodiments of the present application, the technical solutions of the embodiments of the present application are introduced below with two specific examples.

[0189] Please refer to Figure 19, which shows a schematic diagram of a method for detecting an optical fiber link provided by an embodiment of the present application. Figure 19 uses an out-of-band detection method to detect an optical fiber link as an example. As shown in Figure 19, the control device is connected to the optical transmitting device 210 and the optical receiving device 220, respectively.

[0190] As shown in Figure 19, the optical transmitting device 210 includes a transmitter, a switch unit, a detection sequence generation unit, and a data signal generation unit. The switch unit is connected to the transmitter, the detection sequence generation unit, and the data signal generation unit, respectively. The optical receiving device 220 includes a receiver, a sampling and quantization unit, a switch unit, a detection sequence demodulation unit, and a data signal demodulation unit. The receiver, the sampling and quantization unit, and the switch unit are connected in sequence, and the switch unit is connected to the detection sequence demodulation unit and the data signal demodulation unit, respectively. The transmitter and the receiver are connected via an optical fiber link 230, so that the optical transmitting device 210 and the optical receiving device 220 are connected via the optical fiber link 230. For example, the optical transmitting device 210 and the optical receiving device 220 respectively include optical modules (not shown in Figure 19), the optical module in the optical transmitting device 210 includes the transmitter, the switch unit, the detection sequence generation unit and the data signal generation unit, and the optical module in the optical receiving device 220 includes the receiver, the sampling quantization unit, the switch unit, the detection sequence demodulation unit and the data signal demodulation unit.

[0191] The control device is used to control the optical transmitting device 210 and the optical receiving device 220 to enter detection mode or non-detection mode, respectively. After the optical transmitting device 210 and the optical receiving device 220 enter detection mode, the optical transmitting device 210 and the optical receiving device 220 cooperate to detect the transmission performance of the optical fiber link 230. After the optical transmitting device 210 and the optical receiving device 220 enter non-detection mode, the optical transmitting device 210 and the optical receiving device 220 communicate data. Specifically, the control device controls the switch unit in the optical transmitting device 210 to connect the detection sequence generation unit to the transmitter, thereby controlling the optical transmitting device 210 to enter detection mode; the control device controls the switch unit in the optical receiving device 220 to connect the sampling quantization unit to the detection sequence demodulation unit, thereby controlling the optical receiving device 220 to enter detection mode. The control device controls the switch unit in the optical transmitting device 210 to connect the data signal generating unit to the transmitter, thereby controlling the optical transmitting device 210 to enter the non-detection mode; the control device controls the switch unit in the optical receiving device 220 to connect the sampling quantization unit to the data signal demodulation unit, thereby controlling the optical receiving device 220 to enter the non-detection mode.

[0192] In the optical transmitting device 210, a detection sequence generation unit is used to generate a detection sequence, a data signal generation unit is used to generate a data signal, and a switch unit is used to control the detection sequence generation unit or the data signal generation unit to connect to the transmitter. When the detection sequence generation unit is connected to the transmitter, the optical transmitting device 210 is in a detection mode. The transmitter modulates an optical signal using the detection sequence generated by the detection sequence generation unit and transmits the optical signal carrying the detection sequence via the optical fiber link 230. When the data signal generation unit is connected to the transmitter, the optical transmitting device 210 is in a non-detection mode. The transmitter modulates an optical signal using the data signal generated by the data signal generation unit and transmits the optical signal carrying the data signal via the optical fiber link 230. In the optical receiving device 220, a receiver is used to receive an optical signal via the optical fiber link 230 and convert the optical signal into an analog electrical signal. The sampling and quantization unit is used to sample and quantize the analog electrical signal to obtain a digital electrical signal. The switch unit is used to control the detection sequence demodulation unit or the data signal demodulation unit to connect to the sampling and quantization unit. When the detection sequence demodulation unit is in communication with the sampling and quantization unit, the optical receiving device 220 is in a detection mode, in which the detection sequence demodulation unit demodulates the digital electrical signal to obtain a detection sequence, and determines the transmission performance of the optical fiber link 230 based on the detection sequence. When the data signal demodulation unit is in communication with the sampling and quantization unit, the optical receiving device 220 is in a non-detection mode, in which the data signal demodulation unit demodulates the digital electrical signal to obtain a data signal.

[0193] In one example, both the optical transmitting device 210 and the optical receiving device 220 are in detection mode. The transmitter modulates an optical signal using a detection sequence generated by a detection sequence generation unit to obtain an optical signal carrying the detection sequence. The transmitter then transmits the optical signal via an optical fiber link 230. The receiver receives the optical signal carrying the detection sequence via the optical fiber link 230 and converts the optical signal into an analog electrical signal. The sampling and quantization unit samples and quantizes the analog electrical signal to obtain a digital electrical signal. The detection sequence demodulation unit demodulates the digital electrical signal to obtain the detection sequence, and determines the transmission performance of the optical fiber link 230 based on the detection sequence.

[0194] In another example, both the optical transmitting device 210 and the optical receiving device 220 are in a non-detection mode. The transmitter modulates an optical signal using a data signal generated by the data signal generating unit to obtain an optical signal carrying the data signal. The transmitter then transmits the optical signal via the optical fiber link 230. The receiver receives the optical signal carrying the data signal via the optical fiber link 230 and converts the optical signal into an analog electrical signal. The sampling and quantization unit samples and quantizes the analog electrical signal to obtain a digital electrical signal. The data signal demodulation unit demodulates the digital electrical signal to obtain the data signal.

[0195] Please refer to Figure 20, which shows a schematic diagram of another optical fiber link detection method provided by an embodiment of the present application. Figure 20 uses the in-band detection method to detect an optical fiber link as an example. As shown in Figure 20, the control device is connected to the optical transmitting device 210 and the optical receiving device 220 respectively.

[0196] As shown in Figure 20, the optical transmitting device 210 includes a transmitter, a detection sequence generating unit and a data signal generating unit, and the transmitter is connected to the detection sequence generating unit and the data signal generating unit respectively. The optical receiving device 220 includes a receiver, a sampling and quantization unit, a detection sequence demodulation unit and a data signal demodulation unit, and the sampling and quantization unit is connected to the receiver, the detection sequence demodulation unit and the data signal demodulation unit respectively. The transmitter is connected to the receiver via an optical fiber link 230, so that the optical transmitting device 210 is connected to the optical receiving device 220 via the optical fiber link 230. For example, the optical transmitting device 210 and the optical receiving device 220 respectively include an optical module (not shown in Figure 20), the optical module in the optical transmitting device 210 includes the transmitter, the detection sequence generating unit and the data signal generating unit, and the optical module in the optical receiving device 220 includes the receiver, the sampling and quantization unit, the detection sequence demodulation unit and the data signal demodulation unit.

[0197] The control device is used to control the optical transmitting device 210 and the optical receiving device 220 to enter the detection mode or the non-detection mode respectively. After the optical transmitting device 210 and the optical receiving device 220 respectively enter the detection mode, the optical transmitting device 210 and the optical receiving device 220 cooperate to detect the transmission performance of the optical fiber link 230, and the optical transmitting device 210 and the optical receiving device 220 communicate data. After the optical transmitting device 210 and the optical receiving device 220 respectively enter the non-detection mode, the optical transmitting device 210 and the optical receiving device 220 communicate data. For example, the control device controls the transmitter to modulate the detection sequence in the optical signal, thereby controlling the optical transmitting device 210 to enter the detection mode; the control device controls the detection sequence demodulation unit in the optical receiving device 220 to demodulate the detection sequence carried by the optical signal, thereby controlling the optical receiving device 220 to enter the detection mode. The control device controls the transmitter not to modulate the detection sequence in the optical signal, thereby controlling the optical transmitting device 210 to enter the non-detection mode; the control device controls the data signal demodulation unit in the optical receiving device 220 not to demodulate the detection sequence carried by the optical signal, thereby controlling the optical receiving device 220 to enter the non-detection mode.

[0198] In the optical transmitting device 210, the detection sequence generation unit is configured to generate a detection sequence, and the data signal generation unit is configured to generate a data signal. When the optical transmitting device 210 is in detection mode, the transmitter modulates an optical signal using the detection sequence generated by the detection sequence generation unit and the data signal generated by the data signal generation unit, and transmits the optical signal carrying the detection sequence and the data signal via the optical fiber link 230. When the optical transmitting device 210 is in non-detection mode, the transmitter modulates an optical signal using the data signal generated by the data signal generation unit, and transmits the optical signal carrying the data signal via the optical fiber link 230. In the optical receiving device 220, the receiver is configured to receive the optical signal via the optical fiber link 230 and convert the optical signal into an analog electrical signal. The sampling and quantization unit is configured to sample and quantize the analog electrical signal to obtain a digital electrical signal. When the optical receiving device 220 is in detection mode, the detection sequence demodulation unit demodulates the digital electrical signal to obtain a detection sequence and determines the transmission performance of the optical fiber link 230 based on the detection sequence. The data signal demodulation unit demodulates the digital electrical signal to obtain a data signal. When the optical receiving device 220 is in the non-detection mode, the data signal demodulation unit demodulates the digital electrical signal to obtain a data signal.

[0199] In one example, the optical transmitting device 210 and the optical receiving device 220 are both in detection mode. The transmitter modulates the optical signal using the detection sequence generated by the detection sequence generation unit and the data signal generated by the data signal generation unit to obtain an optical signal carrying the detection sequence and the data signal. The transmitter transmits the optical signal via the optical fiber link 230. The receiver receives the optical signal carrying the detection sequence and the data signal via the optical fiber link 230 and converts the optical signal into an analog electrical signal. The sampling and quantization unit samples and quantizes the analog electrical signal to obtain a digital electrical signal. The detection sequence demodulation unit demodulates the digital electrical signal to obtain the detection sequence. The detection sequence demodulation unit determines the transmission performance of the optical fiber link 230 based on the detection sequence. The data signal demodulation unit demodulates the digital electrical signal to obtain the data signal.

[0200] In another example, both the optical transmitting device 210 and the optical receiving device 220 are in non-detection mode. The transmitter modulates an optical signal using a data signal generated by the data signal generating unit to obtain an optical signal carrying the data signal. The transmitter then transmits the optical signal via the optical fiber link 230. The receiver receives the optical signal via the optical fiber link 230 and converts the optical signal into an analog electrical signal. The sampling and quantization unit samples and quantizes the analog electrical signal to obtain a digital electrical signal. The data signal demodulation unit demodulates the digital electrical signal to obtain the data signal.

[0201] It should be noted that the light source, modulator, etc. involved in the embodiment shown in Figure 3 can be located in the transmitter of the optical transmitting device, and the filter involved in the embodiment shown in Figure 3 can be located in the detection sequence demodulation unit of the optical receiving device. The embodiment of the present application does not limit this.

[0202] The above is an introduction to the method embodiments of the present application. The following describes the device embodiments of the present application, which are used to perform the method of the present application. For details not disclosed in the device embodiments, please refer to the method embodiments.

[0203] Please refer to Figure 21, which shows a schematic diagram of a detection device 2100 for an optical fiber link provided in an embodiment of the present application. The detection device 2100 is applied to an optical transmitting device, and the detection device 2100 can be an optical transmitting device or a functional component in the optical transmitting device. For example, the detection device 2100 is an optical transmitting device, an optical module in an optical transmitting device, a light card in an optical transmitting device, or the detection device 2100 is integrated in the optical transmitting device, in an optical module integrated in the optical transmitting device, or in a light card integrated in the optical transmitting device. The detection device 2100 is used to execute the steps performed by the optical transmitting device in the detection method provided in the embodiment shown in Figure 3. For example, the optical transmitting device is the optical transmitting device 210 in the application scenario shown in Figure 2. Referring to Figure 21, the detection device 2100 includes a generation module 2110 and a sending module 2120.

[0204] The generation module 2110 is configured to generate a first optical signal, which carries a detection sequence. This detection sequence is used by an optical receiving device to detect the transmission performance of the optical fiber link. The transmission module 2120 is configured to transmit the first optical signal via the optical fiber link. After transmission via the optical fiber link, the first optical signal becomes a second optical signal, which includes the first optical signal and a reflected optical signal. The functional implementation of the generation module 2110 can refer to the relevant description in S301 above. The functional implementation of the transmission module 2120 can refer to the relevant description in S302 above.

[0205] Optionally, the autocorrelation curve corresponding to the detection sequence meets a preset condition.

[0206] Optionally, the autocorrelation curve corresponding to the detection sequence satisfies a preset condition, including that the autocorrelation curve corresponding to the detection sequence has a characteristic peak.

[0207] Optionally, the detection sequence includes a first sequence and a second sequence, and the autocorrelation curve corresponding to the detection sequence is determined based on the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence, and the autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence.

[0208] Optionally, the first optical signal carries multiple detection sequences, and the multiple detection sequences are periodically distributed; there are boundary markers between adjacent detection sequences in the multiple detection sequences; or, adjacent detection sequences in the multiple detection sequences are continuous.

[0209] Optionally, the detection sequence includes any one of the following: a pseudo-random code sequence; a Gray complementary sequence.

[0210] Optionally, the first optical signal also carries a data signal.

[0211] Optionally, in the first optical signal, a modulation depth of the detection sequence is smaller than a modulation depth of the data signal, and a baud rate of the detection sequence is smaller than a baud rate of the data signal.

[0212] Optionally, in the first optical signal, a ratio of a modulation depth of the detection sequence to a modulation depth of the data signal is smaller than a preset ratio; and a difference between a baud rate of the detection sequence and a baud rate of the data signal is within a preset range.

[0213] Optionally, the generating module 2110 is configured to modulate a driving signal of the light source using the detection sequence so that the light source emits a first light signal.

[0214] Optionally, the generating module 2110 is configured to modulate the optical signal emitted by the light source using the detection sequence to obtain a first optical signal.

[0215] Optionally, the generating module 2110 is configured to modulate a driving signal of the light source using a data signal modulated with the detection sequence so that the light source emits a first light signal.

[0216] In summary, the technical solution provided by the embodiment of the present application is that the optical transmitting device transmits an optical signal carrying a detection sequence through the optical fiber link, which can facilitate the optical receiving device to determine the transmission performance of the optical fiber link based on the detection sequence carried by the optical signal received through the optical fiber link, thereby realizing the detection of the optical fiber link. It can be seen that the embodiment of the present application provides a transmission detection solution, which uses the existing optical transmitting device and optical receiving device of the optical fiber communication system to detect the transmission performance of the optical fiber link. It is possible to detect the optical fiber link without deploying additional equipment such as OTDR in the optical fiber link. Therefore, the hardware implementation of the optical fiber link detection is simple, the detection cost is low, and fault location can be realized. When locating the fault, there is no need for staff to carry instruments to the station for positioning and there is no need to plug and unplug the optical fiber. The implementation process is simple and on-line detection can be realized.

[0217] Please refer to Figure 22, which shows a schematic diagram of another optical fiber link detection device 2200 provided in an embodiment of the present application. The detection device 2200 is applied to an optical receiving device, and the detection device 2200 can be an optical receiving device or a functional component in the optical receiving device. For example, the detection device 2200 is an optical receiving device, an optical module in an optical receiving device, a light card in an optical receiving device, or the detection device 2200 is integrated in the optical receiving device, an optical module integrated in the optical receiving device, or a light card integrated in the optical receiving device. The detection device 2200 is used to execute the steps performed by the optical receiving device in the detection method provided in the embodiment shown in Figure 3. For example, the optical receiving device is the optical receiving device 220 in the application scenario shown in Figure 2. Referring to Figure 22, the detection device 2200 includes a receiving module 2210, a demodulation module 2220 and a determination module 2230.

[0218] The receiving module 2210 is used to receive a second optical signal through an optical fiber link. The second optical signal includes a first optical signal and a reflected optical signal. The first optical signal is an optical signal generated by an optical transmitting device and carries a detection sequence. The demodulation module 2220 is used to demodulate the second optical signal to obtain the detection sequence. The determination module 2230 is used to determine the transmission performance of the optical fiber link based on the demodulated detection sequence.

[0219] The functional implementation of the receiving module 2210 may refer to the relevant description in S303 above, the functional implementation of the demodulation module 2220 may refer to the relevant description in S304 above, and the functional implementation of the determination module 2230 may refer to the relevant description in S305 above.

[0220] Optionally, the autocorrelation curve corresponding to the detection sequence meets a preset condition.

[0221] Optionally, the autocorrelation curve corresponding to the detection sequence satisfies a preset condition, including that the autocorrelation curve corresponding to the detection sequence has a characteristic peak.

[0222] Optionally, the detection sequence includes a first sequence and a second sequence, and the autocorrelation curve corresponding to the detection sequence is determined based on the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence, and the autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence.

[0223] Optionally, the first optical signal carries multiple detection sequences, and the multiple detection sequences are periodically distributed; there are boundary markers between adjacent detection sequences in the multiple detection sequences; or, adjacent detection sequences in the multiple detection sequences are continuous.

[0224] Optionally, the first optical signal carries multiple detection sequences, and there are boundary identifiers between adjacent detection sequences in the multiple detection sequences. The demodulation module 2220 is configured to determine the multiple detection sequences carried by the second optical signal according to the boundary identifier carried by the second optical signal.

[0225] Optionally, the first optical signal carries multiple detection sequences, adjacent detection sequences in the multiple detection sequences are continuous, and the demodulation module 2220 is configured to determine the multiple detection sequences carried by the second optical signal according to characteristics of the detection sequences.

[0226] Optionally, the determination module 2230 is used to: obtain a correlation curve corresponding to the demodulated detection sequence, where the correlation curve is an autocorrelation curve or a cross-correlation curve, and the cross-correlation curve is determined based on the demodulated detection sequence and the pre-acquired detection sequence; and determine the transmission performance of the optical fiber link based on a characteristic peak of the correlation curve corresponding to the demodulated detection sequence.

[0227] Optionally, the determination module 2230 is used to: determine that the optical fiber link is fault-free when the correlation curve corresponding to the demodulated detection sequence has only one characteristic peak; and determine that the optical fiber link is faulty when the correlation curve corresponding to the demodulated detection sequence has multiple characteristic peaks.

[0228] Optionally, the determination module 2230 is further configured to: when the correlation curve corresponding to the demodulated detection sequence has multiple characteristic peaks, determine the fault point on the optical fiber link based on a main peak among the multiple characteristic peaks and secondary peaks among the multiple characteristic peaks. The multiple characteristic peaks include a main peak and at least one secondary peak, and the peak value of the at least one secondary peak is smaller than the peak value of the main peak.

[0229] Optionally, the detection sequence includes any one of the following: a pseudo-random code sequence; a Gray complementary sequence.

[0230] Optionally, the first optical signal also carries a data signal, that is, the first optical signal carries a detection sequence and a data signal.

[0231] Optionally, in the first optical signal, a modulation depth of the detection sequence is smaller than a modulation depth of the data signal, and a baud rate of the detection sequence is smaller than a baud rate of the data signal.

[0232] Optionally, in the first optical signal, a ratio of a modulation depth of the detection sequence to a modulation depth of the data signal is less than a preset ratio; and a difference between a baud rate of the detection sequence and a baud rate of the data signal is within a preset range.

[0233] Optionally, the demodulation module 2220 is configured to filter the second optical signal.

[0234] In summary, the technical solution provided by the embodiment of the present application is that the optical transmitting device transmits an optical signal carrying a detection sequence through the optical fiber link, and the optical receiving device determines the transmission performance of the optical fiber link based on the detection sequence carried by the optical signal received through the optical fiber link, thereby realizing the detection of the optical fiber link. It can be seen that the embodiment of the present application provides a transmission detection solution, which uses the existing optical transmitting device and optical receiving device of the optical fiber communication system to detect the transmission performance of the optical fiber link. It is possible to detect the optical fiber link without deploying additional equipment such as OTDR in the optical fiber link. Therefore, the hardware implementation of the optical fiber link detection is simple, the detection cost is low, and fault location can be realized. When locating the fault, there is no need for staff to carry instruments to the station for positioning and there is no need to plug and unplug the optical fiber. The implementation process is simple and on-line detection can be realized.

[0235] It should be understood that the optical fiber link detection device provided in the embodiments of the present application can also be implemented using an application-specific integrated circuit (ASIC) or a programmable logic device (PLD), and the above-mentioned 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 optical fiber link detection method provided in the above-mentioned method embodiment can also be implemented by software. When the optical fiber link detection method provided in the above-mentioned method embodiment is implemented by software, each module in the above-mentioned optical fiber link detection device can also be a software module.

[0236] An embodiment of the present application provides a device for detecting an optical fiber link. The detection device includes 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 so that the detection device performs 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 an optical transmitting device, an optical module in an optical transmitting device, a light card in an optical transmitting device, an optical receiving device, an optical module in an optical receiving device, a light card in an optical receiving device, etc. The optical transmitting device can be a network device, a terminal device, or a server, and the optical receiving device can also be a network device, a terminal device, or a server.

[0237] In one embodiment, please refer to Figure 23, which shows a schematic diagram of a detection device 2300 for providing another optical fiber link in an embodiment of the present application. The detection device 2300 can be a network device, a terminal device, or a server. The detection device 2300 includes at least one processor 2301 (Figure 23 is illustrated by two processors 2301 as an example), a communication bus 2302, a memory 2303, and at least one communication interface 2304, and the at least one processor 2301, the memory 2303, and the at least one communication interface 2304 are connected via the communication bus 2302. The at least one processor 2301, the memory 2303, and the at least one communication interface 2304 can also be connected using a connection method other than the communication bus 2302.

[0238] The memory 2303 is used to store computer programs for executing the technical solutions of the present application and is controlled by the processor 2301. The computer programs stored in the memory 2303 include but are not limited to program codes, program instructions, data, etc. The memory 2303 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, or 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 compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited to these. The memory 2303 may be independent and connected to the processor 2301 via the communication bus 2302. The memory 2303 may also be integrated with the processor 2301, which is not limited in the embodiment of the present application.

[0239] Processor 2301 can be a general-purpose processor or a dedicated processor. A general-purpose processor is a processor that performs specific steps and / or operations by reading and executing a computer program stored in a memory (e.g., memory 2303). The general-purpose processor may use a computer program stored in a memory (e.g., memory 2303) in the process of performing the above steps and / or operations. The stored computer program can be executed to implement the related functions of the aforementioned demodulation module 2220, determination module 2230, etc. A general-purpose processor is, for example, but not limited to, a central processing unit (CPU). A dedicated processor is a processor specially designed to perform specific steps and / or operations. A dedicated processor is, for example, but not limited to, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. Processor 2301 can implement or execute various logic blocks, modules, and circuits described in conjunction with the disclosure of the embodiments of the present application. Processor 2301 can also be a combination that implements computing functions, for example, including a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like. The processor may be configured to: demodulate the second optical signal to obtain the detection sequence, and determine the transmission performance of the optical fiber link according to the detection sequence.

[0240] Communication bus 2302 is used to transmit information between processor 2301, communication interface 2304, and memory 2303. Communication bus 2302 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, for example. Communication bus 2302 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, FIG23 shows only one thick line, but this does not indicate that there is only one bus or only one type of bus.

[0241] Communication interface 2304 includes input / output (input / output, I / O) interface, physical interface and logical interface etc. for realizing the interface of the device interconnection inside detection device 2300, and for realizing the interface that detection device 2300 is interconnected with other communication equipment.Physical interface can be Ethernet (Ethernet) interface, Fast Ethernet (fast Ethernet, FE) interface, Gigabit Ethernet (gigabit Ethernet, GE) interface, Terabit Ethernet (TbE) interface, 400GE interface, asynchronous transfer mode (asynchronous transfer mode, ATM) interface etc., and it is used to realize that detection device 2300 is interconnected with other equipment.Logical interface is the interface inside detection device 2300, and it is used to realize the device interconnection inside detection device 2300.It is easy to understand that communication interface 2304 is used for detection device 2300 and other equipment or communication network communication, and such as communication interface 2304 is used for the transmission and reception of optical signal between detection device 2300 and other equipment or communication network. The communication interface 2304 can be a device using any transceiver (such as a transmitter, a receiver), and the communication network can be Ethernet, optical transport network (OTN), secret private network (SPN), fiber channel, infiniband, etc.

[0242] In a specific implementation, as an embodiment, the detection device 2300 includes multiple processors 2301. Each of the multiple processors 2301 can be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. The processor here can refer to one or more devices, circuits, and / or processing cores for processing data (such as computer program instructions).

[0243] In a specific embodiment, when detection device 2300 is an optical transmitting device, communication interface 2304 in detection device 2300 is configured to transmit an optical signal carrying a detection sequence. When detection device 2300 is an optical receiving device, communication interface 2304 in detection device 2300 is configured to receive an optical signal carrying a detection sequence. Correspondingly, processor 2301 in detection device 2300 is configured to demodulate the optical signal to obtain the detection sequence, and to determine the transmission performance of the optical fiber link based on the detection sequence. For detailed processing of processor 2301, please refer to the relevant description in the method embodiment shown in FIG. 3 above, and will not be repeated here.

[0244] In another embodiment, please refer to Figure 24, which shows a schematic diagram of another optical fiber link detection device 2400 provided in an embodiment of the present application. The detection device 2400 can be a network device, such as a data communication device such as a switch or a router. As shown in Figure 24, the detection device 2400 includes a main control board and one or more interface boards, and the main control board is communicatively connected to the interface board. The main control board is also called a main processing unit (MPU) or a route processing card. The main control board is responsible for controlling and managing each component in the detection device 2400, including routing calculation, device management and maintenance functions. The interface board is also called a line processing unit (LPU) or a line card. The interface board is used to forward data. In some embodiments, the detection device 2400 may also include a switching fabric board, which is communicatively connected to the main control board and the interface board. The switching fabric board is used to forward data between the interface boards. The switching fabric 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 is communicatively connected to the memory, forwarding chip, and physical interface card. The memory is used to store a forwarding table. The forwarding chip is used to forward 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 2400, the data frame is sent to the CPU for processing. If the destination address of the data frame is not the address of the detection device 2400, the next hop and outgoing interface corresponding to the destination address are searched in the forwarding table based on the destination address, and the data frame is forwarded to the outgoing interface corresponding to the destination address. The forwarding chip can be a network processor (NP). The PIC, also known as a daughter card, can be installed on the interface board and is responsible for converting optical signals into data frames and performing a validity check on the data frames before forwarding them to the forwarding chip for processing. In some embodiments, the central processing unit can also perform the functions of the forwarding chip, such as implementing software forwarding based on a general-purpose CPU, thereby eliminating the need for a forwarding chip in the interface board. The communication connection 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.

[0245] Logically, detection device 2400 comprises a control plane and a forwarding plane. The control plane includes a main control board and a central processing unit (CPU), while the forwarding plane comprises various components that perform forwarding, such as memory, PIC, and network processing unit (NP). The control plane performs functions such as generating a router's forwarding table, processing signaling and protocol messages, and configuring and maintaining status. The control plane sends the generated forwarding table to the forwarding plane. On the forwarding plane, the NP forwards messages received by the PIC of detection device 2400 based on the forwarding table sent by the control plane. The forwarding table sent by the control plane can be stored in memory. In some embodiments, the control plane and forwarding plane can be completely separate and not located on the same device.

[0246] In a specific embodiment, when the detection device 2400 is an optical transmitting device, the interface board in the detection device 2400 is used to generate an optical signal carrying a detection sequence and transmit the optical signal. For the specific process, please refer to the relevant descriptions in S301 to S302 above. When the detection device 2400 is an optical receiving device, the interface board in the detection device 2400 is used to receive an optical signal carrying a detection sequence, demodulate the optical signal to obtain the detection sequence, and determine the transmission performance of the optical fiber link based on the detection sequence. For the specific process, please refer to the relevant descriptions in S303 to S305 above. When the detection device 2400 is an optical receiving device, the main control board can also be used to determine the transmission performance of the optical fiber link based on the detection sequence. For the specific process, please refer to the relevant description in S305 above, which will not be repeated here.

[0247] In a 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.

[0248] The present application also provides an optical fiber link detection device, comprising a processor and an optical device. The optical device is configured to perform the transceiver operation in the embodiment shown in FIG3 ; and the processor is configured to perform operations other than the transceiver operation in the method embodiment shown in FIG3 .

[0249] 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.

[0250] In an optional embodiment, the detection device is an optical module or an optical card.

[0251] Based on the same inventive concept, an embodiment of the present application provides a fiber optic communication system. The fiber optic communication system includes an optical transmitter, an optical receiver, and an optical fiber link. The optical transmitter and the optical receiver are connected via the optical fiber link. The optical transmitter includes a detection device for the optical fiber link as shown in Figures 21, 23, or 24. The optical receiver includes a detection device for the optical fiber link as shown in Figures 22 to 24.

[0252] For example, the optical fiber communication system is shown in FIG1 or FIG2 .

[0253] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed (e.g., by a network device, terminal device, server, optical module, and / or optical fiber card), it implements at least some of the steps of the method embodiment shown in FIG3 , for example, implementing steps S304 and S305.

[0254] Based on the same inventive concept, an embodiment of the present application provides a computer program product, which includes a program or code. When the program or code is executed (e.g., by a network device, terminal device, server, optical module, and / or optical card), it implements at least some of the steps of the method embodiment shown in FIG3 , for example, implementing steps S304 and S305.

[0255] Based on the same inventive concept, an embodiment of the present application provides a chip, which includes a programmable logic circuit and / or program instructions, and when the chip is running, is used to implement at least some steps of the method embodiment shown in FIG3 , for example, implementing steps S304 and S305 .

[0256] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product, which includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. 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 computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center to another website, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) mode. 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 includes one or more available media integrations. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium, or a semiconductor medium (e.g., a solid-state hard disk).

[0257] It should be understood that the term "at least one" in this application refers to one or more, and "a plurality of" refers to two or more. In this application, unless otherwise specified, the symbol " / " generally means or, for example, A / B can mean A or B. The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, for the sake of clarity of description, this application uses words such as "first", "second", and "third" to distinguish between identical or similar items with basically the same functions and effects. Those skilled in the art will understand that words such as "first", "second", and "third" do not limit the quantity and execution order.

[0258] Different types of embodiments, such as method embodiments and device embodiments, provided in the embodiments of the present application can refer to each other. The order of operations of the method embodiments can be appropriately adjusted, and the operations can be increased or decreased in response to the situation. Any technician familiar with this technical field can easily think of different methods within the technical scope disclosed in this application, and they should all be covered within the scope of protection of this application, so they will not be repeated here.

[0259] In the corresponding embodiments provided in the present application, it should be understood that the disclosed devices and the like can be implemented through other structural methods. For example, the device embodiments described above are merely illustrative. For example, the division of modules is merely a logical function division. In actual implementation, there may be other division methods, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. On the other hand, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical or other forms. The modules described as separate components may or may not be physically separated, and the components described as modules may or may not be physical modules, and may be located in one place or distributed on multiple network nodes. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment.

[0260] The above description is merely an exemplary embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A detection method for an optical fiber link, characterized in that Applied to an optical transmission device, the method includes: Generating a first optical signal, the first optical signal carrying a detection sequence for an optical receiving device to detect the transmission performance of the optical fiber link; Transmitting the first optical signal through the optical fiber link, and the first optical signal becomes a second optical signal after being transmitted through the optical fiber link between the optical transmission device and the optical receiving device, and the second optical signal includes the first optical signal and a reflected optical signal.

2. The method according to claim 1, wherein The autocorrelation curve corresponding to the detection sequence satisfies a preset condition.

3. The method according to claim 2, characterized in that, The autocorrelation curve corresponding to the detection sequence satisfies a preset condition including: the autocorrelation curve corresponding to the detection sequence has a characteristic peak.

4. The method according to claim 2 or 3, characterized in that, The detection sequence includes a first sequence and a second sequence, and the autocorrelation curve corresponding to the detection sequence is determined according to the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence, and the autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence.

5. The method according to any one of claims 1 to 4, characterized in that The first optical signal carries a plurality of the detection sequences, and the plurality of detection sequences are periodically distributed; There is a boundary identifier between adjacent detection sequences among the plurality of detection sequences; or Adjacent detection sequences among the plurality of detection sequences are continuous.

6. The method according to any one of claims 1 to 5, characterized in that, The first optical signal further carries a data signal.

7. The method according to claim 6, wherein In the first optical signal, the modulation depth of the detection sequence is less than the modulation depth of the data signal, and the baud rate of the detection sequence is less than the baud rate of the data signal.

8. The method according to any one of claims 1 to 7, characterized in that, The generating the first optical signal includes: Modulating the driving signal of the light source with the detection sequence to cause the light source to emit the first optical signal; or Modulating the optical signal emitted by the light source with the detection sequence to obtain the first optical signal; or Modulating the driving signal of the light source with a data signal modulated with the detection sequence to cause the light source to emit the first optical signal.

9. A detection method for an optical fiber link, characterized in that Applied to an optical receiving device, the method includes: Receiving a second optical signal through the optical fiber link, the second optical signal including a first optical signal and a reflected optical signal, the first optical signal being an optical signal generated by an optical transmission device, and the first optical signal carrying a detection sequence; Demodulating the second optical signal to obtain the detection sequence; Determining the transmission performance of the optical fiber link according to the demodulated detection sequence.

10. The method according to claim 9, wherein The autocorrelation curve corresponding to the detection sequence satisfies a preset condition.

11. The method according to claim 10, wherein The autocorrelation curve corresponding to the detection sequence satisfies a preset condition including: the autocorrelation curve corresponding to the detection sequence has a characteristic peak.

12. The method according to claim 10 or 11, characterized in that The detection sequence includes a first sequence and a second sequence. The autocorrelation curve corresponding to the detection sequence is determined according to the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence. The autocorrelation value at each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value at the position point on the autocorrelation curve of the first sequence and the autocorrelation value at the position point on the autocorrelation curve of the second sequence.

13. The method according to any one of claims 9 to 12, characterized in that, The first optical signal carries a plurality of the detection sequences, and there is a boundary identifier between adjacent detection sequences among the plurality of detection sequences. Demodulating the second optical signal to obtain the detection sequence includes: Determining a plurality of the detection sequences carried by the second optical signal according to the boundary identifier carried by the second optical signal.

14. The method according to any one of claims 9 to 12, characterized in that The first optical signal carries a plurality of the detection sequences, and adjacent detection sequences among the plurality of detection sequences are continuous. Demodulating the second optical signal to obtain the detection sequence includes: Determining a plurality of the detection sequences carried by the second optical signal according to the characteristics of the detection sequence.

15. The method according to any one of claims 9 to 14, characterized in that Determining the transmission performance of the optical fiber link according to the demodulated detection sequence includes: Obtaining a correlation curve corresponding to the demodulated detection sequence, where the correlation curve is an autocorrelation curve or a cross-correlation curve, and the cross-correlation curve is determined according to the demodulated detection sequence and the pre-obtained detection sequence; Determining the transmission performance of the optical fiber link according to the characteristic peak of the correlation curve corresponding to the demodulated detection sequence.

16. The method according to claim 15, characterized in that Determining the transmission performance of the optical fiber link according to the characteristic peak of the correlation curve corresponding to the demodulated detection sequence includes: When the correlation curve corresponding to the demodulated detection sequence has only one characteristic peak, determining that the optical fiber link has no fault; When the correlation curve corresponding to the demodulated detection sequence has multiple characteristic peaks, determining that the optical fiber link has a fault.

17. The method according to claim 16, characterized in that Determining the transmission performance of the optical fiber link according to the characteristic peak of the correlation curve corresponding to the demodulated detection sequence further includes: When the correlation curve corresponding to the demodulated detection sequence has multiple characteristic peaks, determining the fault point on the optical fiber link according to the main peak and the secondary peak among the multiple characteristic peaks.

18. The method according to any one of claims 9 to 17, characterized in that, The first optical signal also carries a data signal.

19. The method according to claim 18, wherein In the first optical signal, the modulation depth of the detection sequence is less than the modulation depth of the data signal, and the baud rate of the detection sequence is less than the baud rate of the data signal.

20. The method according to any one of claims 9 to 19, characterized in that Demodulating the second optical signal includes: filtering the second optical signal.

21. A detection device for an optical fiber link, characterized in that, Applied to an optical transmitting device, the apparatus includes: A generating module, configured to generate a first optical signal, where the first optical signal carries a detection sequence for a optical receiving device to detect the transmission performance of the optical fiber link; A sending module, configured to send the first optical signal through the optical fiber link. After the first optical signal is transmitted through the optical fiber link between the optical sending device and the optical receiving device, it becomes a second optical signal, and the second optical signal includes the first optical signal and a reflected optical signal.

22. The device according to claim 21, characterized in that, The autocorrelation curve corresponding to the detection sequence satisfies a preset condition.

23. The device according to claim 22, characterized in that, The autocorrelation curve corresponding to the detection sequence satisfying a preset condition includes: the autocorrelation curve corresponding to the detection sequence has a characteristic peak.

24. The device according to claim 22 or 23, characterized in that, The detection sequence includes a first sequence and a second sequence. The autocorrelation curve corresponding to the detection sequence is determined according to the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence. The autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence.

25. The device according to any one of claims 21 to 24, wherein The first optical signal carries a plurality of the detection sequences, and the plurality of detection sequences are periodically distributed; There is a boundary identifier between adjacent detection sequences among the plurality of detection sequences; or Adjacent detection sequences among the plurality of detection sequences are continuous.

26. The device according to any one of claims 21 to 25, characterized in that The first optical signal further carries a data signal.

27. The device according to claim 26, characterized in that, In the first optical signal, the modulation depth of the detection sequence is less than the modulation depth of the data signal, and the baud rate of the detection sequence is less than the baud rate of the data signal.

28. The device according to any one of claims 21 to 27, characterized in that, The generating module is configured to: Modulate the driving signal of the light source with the detection sequence to make the light source emit the first optical signal; or Modulate the optical signal emitted by the light source with the detection sequence to obtain the first optical signal; or Modulate the driving signal of the light source with a data signal modulated with the detection sequence to make the light source emit the first optical signal.

29. A detection device for an optical fiber link, characterized in that, Applied to an optical receiving device, the device includes: A receiving module, configured to receive a second optical signal through the optical fiber link. The second optical signal includes a first optical signal and a reflected optical signal. The first optical signal is an optical signal generated by an optical sending device, and the first optical signal carries a detection sequence; A demodulating module, configured to demodulate the second optical signal to obtain the detection sequence; A determining module, configured to determine the transmission performance of the optical fiber link according to the demodulated detection sequence.

30. The device according to claim 29, characterized in that, The autocorrelation curve corresponding to the detection sequence satisfies a preset condition.

31. The device according to claim 30, wherein The autocorrelation curve corresponding to the detection sequence satisfying a preset condition includes: the autocorrelation curve corresponding to the detection sequence has a characteristic peak.

32. The device according to claim 30 or 31, characterized in that, The detection sequence includes a first sequence and a second sequence. The autocorrelation curve corresponding to the detection sequence is determined according to the autocorrelation curve of the first sequence and the autocorrelation curve of the second sequence. The autocorrelation value of each position point on the autocorrelation curve corresponding to the detection sequence is equal to the sum of the autocorrelation value of the position point on the autocorrelation curve of the first sequence and the autocorrelation value of the position point on the autocorrelation curve of the second sequence.

33. The device according to any one of claims 29 to 32, characterized in that, The first optical signal carries a plurality of the detection sequences, and there are boundary identifiers between adjacent ones of the plurality of detection sequences. The demodulation module is configured to determine the plurality of detection sequences carried by the second optical signal according to the boundary identifiers carried by the second optical signal.

34. The device according to any one of claims 29 to 32, characterized in that, The first optical signal carries a plurality of the detection sequences, and adjacent ones of the plurality of detection sequences are continuous. The demodulation module is configured to determine the plurality of detection sequences carried by the second optical signal according to the characteristics of the detection sequences.

35. The device according to any one of claims 29 to 34, characterized in that, The determination module is configured to: Obtain the correlation curve corresponding to the demodulated detection sequence, where the correlation curve is an autocorrelation curve or a cross-correlation curve, and the cross-correlation curve is determined according to the demodulated detection sequence and the pre-obtained detection sequence; Determine the transmission performance of the optical fiber link according to the characteristic peaks of the correlation curve corresponding to the demodulated detection sequence.

36. The device according to claim 35, characterized in that, The determination module is configured to: When there is only one characteristic peak in the correlation curve corresponding to the demodulated detection sequence, determine that the optical fiber link is fault-free; When there are multiple characteristic peaks in the correlation curve corresponding to the demodulated detection sequence, determine that the optical fiber link has a fault.

37. The apparatus according to claim 36, wherein The determination module is further configured to: when there are multiple characteristic peaks in the correlation curve corresponding to the demodulated detection sequence, determine the fault point on the optical fiber link according to the main peak and the secondary peak among the multiple characteristic peaks.

38. The device according to any one of claims 29 to 37, characterized in that, The first optical signal further carries a data signal.

39. The device according to claim 38, characterized in that, In the first optical signal, the modulation depth of the detection sequence is less than the modulation depth of the data signal, and the baud rate of the detection sequence is less than the baud rate of the data signal.

40. The apparatus according to any one of claims 29 to 39, wherein The demodulation module is configured to filter the second optical signal.

41. A detection device for an optical fiber link, characterized in that, Comprising a memory and a processor; The memory is used to store a computer program; the processor is configured to execute the computer program stored in the memory so that the detection device performs at least some steps of the method according to any one of claims 1 to 20.

42. A detection device for an optical fiber link, characterized in that, Comprising a processor and an optical device; The optical device is configured to perform the transceiver operations in the method according to any one of claims 1 to 20; The processor is configured to perform the operations other than the transceiver operations in the method according to any one of claims 1 to 25.

43. The apparatus according to claim 42, wherein The processor includes an optical digital signal processor ODSP; The optical device includes at least one of an optical transmitter or an optical receiver.

44. The device according to claim 42 or 43, characterized in that the detection device is an optical module or an optical line card.

45. An optical fiber communication system, characterized in that, It includes an optical transmission device, an optical reception device and an optical fiber link. The optical transmission device is connected to the optical reception device through the optical fiber link. The optical transmission device includes the detection device according to any one of claims 21 to 28, 41 to 44, and the optical reception device includes the detection device according to any one of claims 29 to 44.

46. A computer-readable storage medium, characterized in that, A computer program is stored in the computer-readable storage medium, and when the computer program is executed, at least some steps of the method according to any one of claims 1 to 20 are implemented.

47. A computer program product, characterized in that, The computer program product includes a program or code, and when the program or code is executed, at least some steps of the method according to any one of claims 1 to 20 are implemented.

Images