Signal processing method, device and system

Abstract

The present application discloses a signal processing method, device and system, which belongs to the field of optical communication. The method includes: obtaining a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a relationship parameter in an optical transmission link, the relationship parameter is used to reflect the relationship between the correlation of the upper sideband and the lower sideband of the signal in the optical transmission link and the frequency deviation; obtaining a second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link; obtaining a target relationship parameter of a target signal received through the optical transmission link; obtaining a target signal-to-noise ratio of the target signal; based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship, determining the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal. The present application can effectively distinguish between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal. The present application is used for the detection of the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio.

Description

Technical Field

[0001] The present application relates to the field of optical communications, and in particular to a signal processing method, device and system. Background Art

[0002] In an optical transmission system, operators can use an optical signal-to-noise ratio monitoring device to detect the optical signal-to-noise ratio (OSNR) in an optical transmission link to evaluate the quality of transmission (QoT) of the optical transmission link. However, the OSNR actually includes the linear signal-to-noise ratio caused by optical amplifiers and the nonlinear signal-to-noise ratio caused by the optical transmission link itself. Currently, there is an urgent need for a signal processing method that can effectively distinguish the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal. Summary of the invention

[0003] The embodiment of the present application provides a signal processing method, device and system. The technical solution is as follows:

[0004] In a first aspect, a signal processing method is provided, the method comprising:

[0005] A first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a relationship parameter in an optical transmission link is obtained, wherein the relationship parameter is used to reflect the relationship between the correlation of an upper sideband and a lower sideband of a signal in the optical transmission link and a frequency deviation; a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a signal-to-noise ratio in the optical transmission link is obtained; a target relationship parameter of a target signal received through the optical transmission link is obtained; a target signal-to-noise ratio of the target signal is obtained; and based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship, a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal are determined.

[0006] The present application establishes a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a drop rate in an optical transmission link, and a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a signal-to-noise ratio in an optical transmission link, and based on the two relationships, uses the actually obtained target relationship parameters and target signal-to-noise ratio to determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of the target signal, thereby achieving effective distinction between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of the signal.

[0007] In an optional implementation, the first relationship is represented by a first relational expression whose independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio and whose dependent variable is the relationship parameter; the second relationship is represented by a second relational expression whose independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio and whose dependent variable is the signal-to-noise ratio; and the process of determining the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship includes: substituting the target relationship parameter into the first relational expression, substituting the target signal-to-noise ratio into the second relational expression, and obtaining the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal by solving a set of two-variable linear equations.

[0008] In the embodiment of the present application, the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal are obtained by solving equations. The obtaining method is simple and fast, and the calculation efficiency is high.

[0009] Since chromatic dispersion will cause a certain time delay to signals of different frequencies in the optical transmission link, and the upper and lower sidebands of the target signal correspond to different frequencies, the upper and lower sidebands will produce a time domain offset during the transmission process, which will affect the accuracy of the correlation between the upper and lower sidebands of the determined target signal, thereby affecting the detection accuracy of the target relationship parameters. Therefore, after receiving the digital signal, the signal processing device performs chromatic dispersion compensation on the received digital signal to obtain the digital signal after chromatic dispersion compensation. Afterwards, the signal processing device detects the relationship parameters of the digital signal after chromatic dispersion compensation to obtain the target relationship parameters. In this way, the time calibration of the digital signal is achieved, thereby improving the accuracy of the acquired target relationship parameters. Among them, chromatic dispersion compensation can be achieved by using a time domain digital filter or a frequency domain digital equalizer to correct the phase of the received signal.

[0010] In an optional implementation, the process of obtaining the first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameter in the optical transmission link includes: determining the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three signals in the optical transmission link, obtaining at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different; obtaining the relationship parameter of each of the at least three signals; based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained relationship parameters, fitting to obtain the first relationship. For example, the at least three signals have at least one different parameter: transmission power, amplification factor of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

[0011] Since both linear noise and nonlinear noise will destroy the correlation between the upper and lower sidebands of the signal spectrum. However, linear noise is flat in the spectrum, while nonlinear noise is not flat in the spectrum. Therefore, when there is a frequency offset, the influence of linear noise and nonlinear noise on the correlation between the upper and lower sidebands of the spectrum is also different. Therefore, a binary linear equation can be established to reflect the first relationship between the correlation of the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio and the frequency. For example, the first relationship can be expressed by the following first relationship:

[0012]

[0013] Among them, A represents the relationship parameter, SNR linear Represents the linear signal-to-noise ratio, SNR nonlinear represents the nonlinear signal-to-noise ratio, B1 represents the contribution of linear noise to the relationship parameter A, B2 represents the contribution of nonlinear noise to the relationship parameter A, and B3 represents the bias introduced by other inherent factors. For example, the inherent factors include the noise introduced by the transmitter, the noise introduced by the receiver, and / or the resolution of the receiving end (such as a coherent receiver).

[0014] In a first optional manner, the process of obtaining the relationship parameters of each of the at least three signals may include: loading at least two different frequency deviations on the first signal in the digital domain to obtain at least two sub-signals, the first signal being any one of the at least three signals, and the relationship parameters of the first signal being used to reflect the relationship between the correlation of the upper sideband and the lower sideband of the first signal and the frequency deviation. Determine the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals; based on the at least two frequency deviations and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, fit the relationship parameters of the first signal.

[0015] In a second optional manner, the process of obtaining the relationship parameters of each of the at least three signals may include: receiving at least two sub-signals, the at least two sub-signals being signals obtained by loading at least two different frequency offsets on the first signal, for example, signals obtained by a coherent receiver by loading at least two different frequency offsets on the first signal. The first signal is any one of the at least three signals, and the relationship parameters of the first signal are used to reflect the relationship between the correlation of the upper sideband and the lower sideband of the first signal and the frequency offset. Determine the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals; based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, fit the relationship parameters of the first signal.

[0016] In the embodiment of the present application, the upper sideband component (i.e., part of the upper sideband) and the lower sideband component (i.e., part of the lower sideband) of each sub-signal can be obtained by filtering, and then the correlation between the upper sideband component and the lower sideband component can be used to determine the correlation between the upper sideband and the lower sideband. In this way, the overall correlation between the upper sideband and the lower sideband can be reflected by the partial correlation between the upper sideband and the lower sideband, reducing the calculation complexity of the correlation.

[0017] For example, the process of determining the correlation between the upper sideband and the lower sideband of each sub-signal in at least two sub-signals includes:

[0018] For each of the at least two sub-signals, an upper sideband component obtained by filtering the upper sideband component of the sub-signal is obtained, and a lower sideband component obtained by filtering the lower sideband component of the sub-signal is obtained, and a correlation between the upper sideband component and the lower sideband component is used as a correlation between an upper sideband and a lower sideband of the sub-signal; wherein, the filtering positions of the upper sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering bandwidth of the upper sideband components of the same sub-signal is the same as the filtering bandwidth of the lower sideband components, so that the correlation between the upper sideband components and the lower sideband components can be determined under the same filtering bandwidth, and there is no need to align the upper sideband components and the lower sideband components in terms of bandwidth, thereby reducing the calculation complexity of the correlation.

[0019] In an optional implementation, the process of obtaining the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link includes:

[0020] Determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, wherein the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different; obtain the signal-to-noise ratio of each of the at least three signals; and obtain the second relationship by fitting based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the obtained signal-to-noise ratios. For example, the at least three signals have at least one different parameter: transmission power, amplification factor of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

[0021] Since both linear noise and nonlinear noise will affect the overall signal-to-noise ratio (for example, the aforementioned SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum) when there is no frequency deviation, but the nonlinear noise in the upper and lower sideband signals is not completely uncorrelated like Gaussian noise, nor is it as strongly correlated with the signal itself, the nonlinear noise does not contribute to the overall signal-to-noise ratio, but the contribution is not as large as that of linear noise. Therefore, a two-variable first-order equation can be established to reflect the second relationship between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio and the signal-to-noise ratio. For example, the second relationship can be expressed by the following second relationship:

[0022]

[0023] Among them, SNR meas Represents signal-to-noise ratio, SNR linear Represents the linear signal-to-noise ratio, SNR nonlinear represents the nonlinear signal-to-noise ratio, C1 represents the linear noise to signal-to-noise ratio SNR meas C2 represents the contribution of nonlinear noise to the nonlinear signal-to-noise ratio SNR nonlinear C3 represents the bias introduced by other inherent factors.

[0024] Before fitting, at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained signal-to-noise ratios are known numbers; C1, C2, and C3 are unknown numbers. By substituting at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained signal-to-noise ratios into the second relational expression, C1, C2, and C3 can be obtained by fitting. Substituting the fitted C1, C2, and C3 into the second relational expression, a second relational expression with known coefficients can be obtained.

[0025] In an optional implementation, the relationship parameter is a drop rate, which is a drop rate at which the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link decreases as the frequency offset increases.

[0026] The relationship between the correlation and the frequency deviation can be expressed by a cubic function. The cubic function can more accurately reflect the relationship between the correlation and the frequency deviation. Using the cubic function to describe the relationship between the correlation and the frequency deviation can effectively improve the accuracy of the final fitting result. For example, the cubic function is the first formula, which is: y = Ax 3 +Z, where A represents the drop rate, y represents the correlation, x represents the frequency deviation, and Z represents the bias introduced by other inherent factors, which is not zero.

[0027] In a second aspect, a signal processing device is provided, the device comprising: at least one module, and the at least one module can be used to implement the signal processing method provided by the above-mentioned first aspect or various possible implementations of the first aspect.

[0028] In a third aspect, a signal processing system is provided, which includes: a coherent receiver and a signal processing device as described in any one of the second aspects; the coherent receiver is used to receive an optical signal from an optical transmission link, and convert the received optical signal into a digital signal, and send the converted digital signal to the signal processing device.

[0029] In an optional implementation, the coherent receiver includes:

[0030] A local oscillator laser is used to generate coherent light; a polarization beam splitter is used to split an optical signal transmitted by an optical transmission link into a first polarization light and a second polarization light perpendicular to each other, and to split the coherent light into a third polarization light and a fourth polarization light perpendicular to each other;

[0031] Two 90° mixers, wherein one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light; a photodetector is used to convert the optical signals output by the two 90° mixers into analog currents; a filter is used to filter the analog currents to obtain an electrical signal corresponding to the target signal; and an analog-to-digital converter is used to convert the electrical signal corresponding to the target signal into a digital signal. The photodetector may be a balanced photodetector, which can achieve noise cancellation and reduce the noise in the output analog current.

[0032] Correspondingly, the signal processing device includes: a first digital bandpass filter, used for filtering the upper sideband component of the received signal; and a second digital bandpass filter, used for filtering the lower sideband component of the received signal.

[0033] In another optional implementation, the system also includes: a splitter, the number of the coherent receivers is 2, the splitter is used to receive an optical signal from an optical transmission link, and divide the received optical signal into two optical signals, which are respectively input into two coherent receivers, one of the two coherent receivers is used to perform upper sideband component filtering, and the other coherent receiver is used to perform lower sideband component filtering.

[0034] Optionally, each of the aforementioned coherent receivers comprises:

[0035] A local oscillator laser is used to generate coherent light; a polarization beam splitter is used to split an optical signal transmitted by an optical transmission link into a first polarization light and a second polarization light perpendicular to each other, and to split the coherent light into a third polarization light and a fourth polarization light perpendicular to each other;

[0036] Two 90° mixers, one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light; a photodetector is used to convert the optical signals output by the two 90° mixers into analog currents; a low-pass filter is used to filter the analog current to obtain an electrical signal of a corresponding sideband component; and an analog-to-digital converter is used to convert the electrical signal of the corresponding sideband component into a digital signal.

[0037] In an optional example, the aforementioned coherent receiver is further used to add a frequency offset to the received optical signal. For example, at least two different frequency offsets are added to the received signal to obtain at least two sub-signals.

[0038] Optionally, when the signal processing system includes two coherent receivers, the two coherent receivers are used to load frequency deviation for the received optical signal. For example, the center frequency of the optical signal is T, the baud rate of the optical signal is E, and the frequency deviation to be loaded is L. Then, the center frequency of the local oscillator laser of a coherent receiver corresponding to the upper sideband of the signal is adjusted to T+L+E / 2, so that the position of the signal spectrum of the electrical signal corresponding to the upper sideband of the optical signal will move forward by L relative to the origin; the center frequency of the local oscillator laser of another coherent receiver corresponding to the lower sideband of the signal is adjusted to T+LE / 2, so that the position of the signal spectrum of the electrical signal corresponding to the lower sideband of the optical signal will move forward by L relative to the origin. When the two coherent receivers are also used to perform upper sideband component filtering and lower sideband component filtering respectively, the positions of the signal spectra of the electrical signals corresponding to the upper sideband components and the lower sideband components obtained by the final filtering are both moved forward by L relative to the origin.

[0039] Illustratively, the system further includes: a power measuring device, the power measuring device being configured to receive an optical signal from the optical transmission link and measure the power of a target signal in the optical signal.

[0040] The local oscillator laser has a plurality of adjustable center frequencies.

[0041] In a fourth aspect, the present application provides a computer device, the computer device comprising a processor and a memory. The memory stores computer instructions; the processor executes the computer instructions stored in the memory, so that the computer device executes the method provided by the first aspect or various possible implementations of the first aspect, so that the computer device deploys the signal processing device provided by the second aspect or various possible implementations of the second aspect.

[0042] In a fifth aspect, the present application provides a computer-readable storage medium, which stores computer instructions, and the computer instructions instruct the computer device to execute the method provided by the above-mentioned first aspect or various possible implementations of the first aspect, or the computer instructions instruct the computer device to deploy the signal processing device provided by the above-mentioned second aspect or various possible implementations of the second aspect.

[0043] In a sixth aspect, the present application provides a computer program product, the computer program product comprising computer instructions, the computer instructions being stored in a computer-readable storage medium. A processor of a computer device may read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the method provided by the first aspect or various possible implementations of the first aspect, and the computer device deploys the signal processing device provided by the second aspect or various possible implementations of the second aspect.

[0044] In a seventh aspect, a chip is provided, which may include a programmable logic circuit and / or program instructions, and when the chip is running, it is used to implement any signal processing method as described in the first aspect.

[0045] In an eighth aspect, an optical transmission system is provided, the optical transmission system comprising any signal processing system according to the third aspect, and illustratively, the optical transmission system further comprises one or more optical devices, such as a WSS and / or an optical amplifier.

[0046] The beneficial effects of the technical solution provided by the embodiment of the present application are:

[0047] The present application establishes a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a drop rate in an optical transmission link, and a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a signal-to-noise ratio in an optical transmission link, and based on the two relationships, uses the actually obtained target relationship parameters and target signal-to-noise ratio to determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of the target signal, thereby achieving effective distinction between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of the signal.

[0048] Furthermore, the embodiment of the present application can simultaneously acquire the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal, and the acquisition efficiency of the signal-to-noise ratio is high, which facilitates the staff to conduct a comprehensive and effective analysis of the transmission quality of the optical transmission link.

[0049] Furthermore, the signal processing method provided in the embodiment of the present application does not limit the modulation format supported by the DSP, and can support the monitoring of the linear signal-to-noise ratio and nonlinear signal-to-noise ratio of signals of different modulation formats, thereby improving the monitoring flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1It is a schematic diagram of an application environment of an optical transmission system involved in a signal processing method provided in an embodiment of the present application;

[0051] Figure 2 is a schematic diagram of an application environment of an optical transmission system involved in another signal processing method provided in an embodiment of the present application;

[0052] Figure 3 It is a flowchart of a signal processing method provided by an embodiment of the present application;

[0053] Figure 4 This is a schematic diagram of the relationship between the wavelength and optical power of a signal provided in an embodiment of the present application;

[0054] Figure 5 It is a schematic diagram of the frequency offset loading principle of an optical transmission system involved in a signal processing method provided in an embodiment of the present application;

[0055] Figure 6 It is a schematic diagram of the frequency offset loading principle of an optical transmission system involved in another signal processing method provided in an embodiment of the present application;

[0056] Figure 7 It is a schematic diagram of the filtering principle of an optical transmission system involved in a signal processing method provided in an embodiment of the present application;

[0057] Figure 8 They are respectively schematic diagrams of filtering principles of an optical transmission system involved in another signal processing method provided in an embodiment of the present application;

[0058] Fig. 9 The embodiment of the present application provides Figure 8 A schematic diagram of filtering principle of an optical transmission system involved in a signal processing method based on the invention;

[0059] Fig.10 is a schematic diagram of a fitting result of a drop rate of a first signal provided in an embodiment of the present application;

[0060] Fig.11 It is a schematic diagram of the principle of calculating the signal-to-noise ratio of a signal using an out-of-band interpolation method provided in an embodiment of the present application;

[0061] Fig.12 The present invention provides a schematic diagram of the principle of using an error vector amplitude calculation method to calculate the signal-to-noise ratio of a signal;

[0062] Fig.13 is a structural schematic diagram of a signal processing device provided in an embodiment of the present application;

[0063] Fig.14 is a structural diagram of a first relationship acquisition module provided in an embodiment of the present application;

[0064] Fig.15 It is a possible basic hardware architecture of the computer device provided in the embodiment of the present application;

[0065] Fig.16 is a structural schematic diagram of a signal processing system provided in an embodiment of the present application;

[0066] Fig.17 is a structural diagram of another signal processing system provided in an embodiment of the present application;

[0067] Fig.18 is a structural diagram of another signal processing system provided in an embodiment of the present application;

[0068] Fig.19 is a structural diagram of another signal processing system provided in an embodiment of the present application;

[0069] Fig. 20 is a structural schematic diagram of a signal processing system provided by another embodiment of the present application;

[0070] Fig.21 is a structural schematic diagram of another signal processing system provided by another embodiment of the present application;

[0071] Fig. 22 It is a structural diagram of yet another signal processing system provided in another embodiment of the present application. DETAILED DESCRIPTION

[0072] In order to make the principles and technical solutions of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0073] Optical fiber (also known as line fiber) communication is a communication method that uses optical signals as information carriers and optical fibers as transmission media. Figure 1 and Figure 2 The schematic diagram is an application environment diagram of an optical transmission system (also called an optical fiber communication system or an optical transmission network) involved in the signal processing method provided in the embodiment of the present application. The optical transmission system is based on optical fiber communication and includes one or more optical devices. Figure 1 Assume that the optical transmission system includes a wavelength selective switch (Wavelength Selective Switching, WSS) 101 and an optical amplifier 102; Figure 2 Assume that the optical transmission system includes two WSSs 101 and two optical amplifiers 102. For example, the optical amplifier 102 is an erbium doped fiber amplifier (EDFA) or a Raman amplifier.

[0074] The embodiments of the present application do not limit the number and types of optical devices included in the optical transmission system. Figure 1 and Figure 2 The optical transmission system in the network can use wavelength division multiplexing (WDM) technology to transmit business information through optical signals.

[0075] In the aforementioned optical transmission system, the transmission quality of the optical signal can be evaluated by monitoring the optical signal-to-noise ratio (abbreviated as signal-to-noise ratio) of the optical transmission link (such as optical fiber). The signal-to-noise ratio refers to the ratio of signal power to noise power. However, the current signal processing method can only monitor the overall signal-to-noise ratio of the optical transmission link, and cannot distinguish between nonlinear signal-to-noise ratio and linear signal-to-noise ratio. As a result, it is impossible to accurately evaluate the transmission quality of the optical transmission link. Furthermore, when a problem occurs in the optical transmission system, it is also impossible to accurately locate the source of the problem based on the acquired signal-to-noise ratio.

[0076] The embodiment of the present application provides a signal processing method, which can effectively distinguish the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of an optical transmission link. The signal processing method can be applied to a signal processing device, which can be arranged on the optical transmission link of the aforementioned optical transmission system. Figure 3 This is a flow chart of a signal processing method provided by an embodiment of the present application. In practical applications, the signal processing device may need to process one or more signals. To facilitate the reader's understanding, the subsequent embodiments are described using one signal processed by the device as an example. The processing process of other signals refers to the processing process of the signal. Figure 3 As shown, the method includes:

[0077] S201. A signal processing device obtains a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio, and a relationship parameter in an optical transmission link, where the relationship parameter is used to reflect a relationship between a correlation between an upper sideband and a lower sideband of a signal in the optical transmission link and a frequency deviation.

[0078] For example, the relationship parameter is a droop rate or other parameters obtained by deforming the droop rate, where the droop rate is a rate at which the correlation between the upper sideband and the lower sideband of a signal in an optical transmission link decreases as the frequency offset increases.

[0079] Assuming that the center frequency of a signal is FO, the upper sideband of the signal is the frequency of the signal that is higher than FO, and the lower sideband of the signal is the frequency of the signal that is lower than FO. Since the wavelength and frequency of the signal are negatively correlated, accordingly, assuming that the center wavelength of the signal is λ, the upper sideband of the signal is the wavelength of the signal that is lower than λ, and the lower sideband of the signal is the wavelength of the signal that is higher than λ. Figure 4 FIG. 1 is a schematic diagram of the relationship between the wavelength and optical power of a signal provided in an embodiment of the present application. Figure 4Taking the signal X as an example, the wavelength range of the signal X is λ1-α to λ1+α, and the central wavelength is λ1. Then the wavelength range of the upper sideband of the signal X is λ1-α to λ1, and the wavelength range of the lower sideband is λ1 to λ1+α.

[0080] In the same optical transmission system, the correlation between the upper sideband and the lower sideband of the signal transmitted in the optical transmission link changes with the change of frequency deviation. For example, the correlation between the upper sideband and the lower sideband of the signal will decrease with the increase of frequency deviation, and usually decreases at a fixed rate of decrease. The change relationship (also called the rate of change) of the aforementioned correlation and frequency deviation is related to the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and the relationship parameter can reflect the change relationship. Therefore, the embodiment of the present application obtains a first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameter in the optical transmission link, so as to determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of the signal to be measured in the optical transmission link (referred to as the target signal in the embodiment of the present application) based on the first relationship in the subsequent process.

[0081] In an optional manner, the process of obtaining the first relationship includes the following steps:

[0082] A1. A signal processing device determines a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio corresponding to each of at least three signals in an optical transmission link, and obtains at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, wherein the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different. For example, the at least three signals include N signals, and the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios include N linear signal-to-noise ratios: SNR linear1 , SNR linear2 , …SNR linearN and N nonlinear signal-to-noise ratios: SNR nonlinear1 , SNR nonlinear2 , …SNR nonlinearN Among them, SNR linear1 and SNR nonlinear1 is a pair of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, SNR linear2 and SNR nonlinear2 is a pair of linear signal-to-noise ratio and nonlinear signal-to-noise ratio. By analogy, we can finally obtain N pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio (SNR linear , SNR nonlinear ).

[0083] The embodiment of the present application assumes that the at least three signals are all optical signals. The signal processing device can obtain at least three signals with different linear signal-to-noise ratios and nonlinear signal-to-noise ratios in a variety of ways. The embodiment of the present application is described by taking the following optional implementation methods as examples:

[0084] In the first optional implementation, according to the noise accumulation formula and nonlinear theoretical equation of the optical amplifier (such as EDFA), the transmission power of the transmitter affects both the linear noise (also called Gaussian noise) and the nonlinear noise of the transmitted signal, so the at least three signals can be obtained by adjusting the transmission power of the transmitter on the optical transmission link. Accordingly, the transmission powers of the at least three signals are different.

[0085] The above optical amplifier noise accumulation formula is:

[0086]

[0087] is the power of ASE noise, NF n is the noise figure of the nth optical amplifier (such as EDFA) in the optical transmission link, G n is the gain multiple of the nth optical amplifier (such as EDFA) in the optical transmission link, h is Planck's constant, ν is the channel center frequency, and B signal is the signal bandwidth.

[0088] The above nonlinear theoretical equations satisfy: is the power of nonlinear noise, which can be obtained by integrating the nonlinear power spectrum density of the signal. The nonlinear power spectrum density of the signal is obtained by superimposing and summing the nonlinear power spectrum density generated by each section of optical fiber in the optical transmission link. Among them, the nonlinear power spectrum density generated by the nth section of optical fiber is:

[0089]

[0090] in, represents the nonlinear power spectrum density generated by the nth section of optical fiber, G(f) is the power spectrum of the signal, f represents the frequency (also called frequency domain), L n ,α,β2,andγare the length,loss coefficient,dispersion coefficient and nonlinear coefficient of the nth optical fiber respectively, and exp represents the exponential function with the natural constant e as the base.

[0091] The optical transmission system may include multiple optical signal nodes, which may also be referred to as transmission nodes (English: Transmission node). For example, the optical signal node is a reconfigurable optical add-drop multiplexer (ROADM). Each optical signal node includes one or more optical devices. For example, Figure 1 One WSS 101 and one optical amplifier 102 belong to one optical signal node. Figure 2The two WSS101 and the two optical amplifiers 102 in the optical signal processing device belong to one optical signal node. The signal processing device can be set in one optical signal node or between two optical signal nodes. The aforementioned transmitter refers to a transmitter upstream of the signal processing device, that is, the signal sent by the transmitter can pass through the signal processing device.

[0092] In one optional example, the signal processing device receives the at least three signals respectively by manually adjusting the transmission power of the transmitter. In another optional example, the signal processing device can establish a communication connection with the transmitter and control the transmitter to adjust the transmission power so that the signal processing device receives the at least three signals respectively.

[0093] In a second optional implementation, since the amplification factor of the optical amplifier affects both the linear noise and the nonlinear noise of the signal on the optical transmission link, the at least three signals can be obtained by adjusting the amplification factor of the optical amplifier on the optical transmission link. Accordingly, the amplification factors of the optical amplifiers corresponding to the at least three signals are different.

[0094] Since the amplification factor of the optical amplifier located after the signal processing device has little effect on the signal processed by the signal processing device, the optical amplifier to be adjusted is an optical amplifier arranged upstream of the signal processing device. The optical amplifier has a plurality of different amplification factors, and its amplification factor is adjustable. In an optional example, the signal processing device receives the at least three signals respectively by manually adjusting the amplification factor of the optical amplifier. In another optional example, the signal processing device can establish a communication connection with the optical amplifier and control the optical amplifier to adjust the amplification factor so that the signal processing device receives the at least three signals respectively.

[0095] In a third optional implementation, since different types of optical amplifiers affect both linear noise and nonlinear noise of signals on an optical transmission link, the at least three signals are obtained by adjusting the type of optical amplifier on the optical transmission link. Accordingly, the at least three signals correspond to different types of optical amplifiers.

[0096] Since the type of optical amplifier located after the signal processing device has little effect on the signal processed by the signal processing device, the aforementioned adjusted optical amplifier is an optical amplifier arranged upstream of the signal processing device. In an optional example, the type of optical amplifier is adjusted by manually disassembling and replacing different optical amplifiers so that the signal processing device can receive the at least three signals respectively. In another optional example, an optical amplifier switching device can be provided on the optical transmission link before the signal processing device, which is used to switch different types of optical amplifiers to the optical transmission link so that the signal processing device can receive the at least three signals respectively. The optical amplifier switching device can be controlled manually or by the signal processing device.

[0097] In a fourth optional implementation, the at least three signals are obtained by actively loading different noises on the optical transmission link. Accordingly, the actively loaded noises corresponding to the at least three signals are different.

[0098] For example, a noise adding device can be arranged upstream of the signal processing device to actively add different noises to the optical transmission link so that the signal processing device receives the at least three signals respectively. The noise adding device can be controlled manually or by the signal processing device.

[0099] In an optional manner, the true value of the linear signal-to-noise ratio can be obtained by a traditional dropout method or a calculation formula for the linear signal-to-noise ratio. Taking the dropout method as an example, assuming that the first signal is any one of the at least three signals mentioned above, the process of obtaining the linear signal-to-noise ratio of the first signal includes: turning on the channel transmission of the first signal, and reading the total power s1 of the signal and linear noise in the channel through a spectrometer at the receiving end. Subsequently, the channel transmission of the first signal is turned off, and the power s2 of the linear noise in the channel is read through a spectrometer at the receiving end. The true value of the linear signal-to-noise ratio of the first signal can be obtained by calculating the two powers obtained. For example, the true value of the linear signal-to-noise ratio of the first signal is equal to s2 / (s1-s2).

[0100] In an optional manner, the true value of the nonlinear signal-to-noise ratio can be calculated by a theoretical model, such as a Gaussian noise model (GNmodel) or the aforementioned nonlinear theoretical equation. For another example, the theoretical model is a model obtained by modeling in the time domain that approximates additive Gaussian noise.

[0101] Optionally, the nonlinear signal-to-noise ratio may also be obtained by adding a pilot signal to a signal transmitted in the optical transmission link.

[0102] A2. The signal processing device obtains a relation parameter of each of at least three signals.

[0103] The embodiment of the present application assumes that the signal processing device is a digital signal processing (DSP) device, which is in the digital domain. Figure 5 and Figure 6 They are schematic diagrams of the frequency offset loading principle of the signal processing system involved in the two signal processing methods provided in the embodiments of the present application. The signal processing system includes: a coherent receiver 301 and a signal processing device 302. The coherent receiver 301 is used to receive an optical signal from an optical transmission link, and convert the received optical signal into a digital signal, and send the converted digital signal to the signal processing device 302; the signal processing device 302 is used to process the received digital signal. The use of a coherent receiver to acquire an optical signal can retain the complete information of the optical signal, which is convenient for subsequent chromatic dispersion (CD) compensation and / or frequency offset loading. The complete information of the optical signal includes the intensity and phase of the signal. It is worth noting that in actual implementation, the coherent receiver can also be replaced by other types of receivers, as long as the complete information of the optical signal can be acquired through the other type of reception.

[0104] like Figure 5 As shown, it is assumed that the first signal is any one of at least three signals transmitted in the optical transmission link. Figure 5 In the method, a frequency deviation is applied to a first signal in a digital domain (ie, at a signal processing device) to obtain a relational parameter of the first signal at the signal processing device. Figure 6 In the method, a frequency offset is applied to a first signal in an optical domain (ie, at a coherent receiver) so as to obtain a relational parameter of the first signal at a signal processing device.

[0105] like Figure 5 As shown, the process of obtaining the relationship parameter of the first signal includes:

[0106] A21. A signal processing device applies at least two different frequency offsets to the first signal in the digital domain to obtain at least two sub-signals.

[0107] Assuming that the first signal is an optical signal, the signal processing device receives a digital signal converted from the first signal, and processes the digital signal to realize the processing of the first signal by the signal processing device in the digital domain. The processing process includes: loading at least two different frequency deviations on the first signal in the digital domain, and the process of loading the frequency deviation can be realized by a specified algorithm. For example, it is assumed that the first sub-signal is any seed signal of at least two sub-signals obtained by adding at least two carrier frequency deviations to the first signal. The acquisition process of the first sub-signal includes: determining the initial phase increment factor based on the baud rate of the first signal in the digital domain and the target frequency deviation to be introduced, and the initial phase increment factor is the ratio of the target frequency deviation to the baud rate of the first signal; multiplying the code elements in the first signal in the digital domain by the corresponding phase increment factor to obtain the first sub-signal. Among them, the phase increment factor corresponding to the qth code element is the product of the initial phase increment factor and q, 1≤q≤m, and m is the number of code elements in the first signal.

[0108] For example, assume that the baud rate of the first signal in the digital domain is 28 GHz, the target frequency deviation to be introduced for the first sub-signal is 1 GHz, and the phase increment factor is 1 / 28. Assume that the first signal is a signal sequence of length m: [A1, A2, A3, A4…A m ], where A q is the qth symbol in the first signal, 1≤q≤m. Then the process of frequency offset loading the first signal in the digital domain includes: multiplying the signal sequence by the corresponding phase increment factors in sequence to obtain the following signal sequence, which is the first sub-signal:

[0109] [A1×exp(1i×2π×(1 / 28)),A2×exp(1i×2π×(2 / 28)),A3×exp(1i×2π×(3 / 28)),A4×exp(1i×2π×(4 / 28)),…A m ×exp(1i×2π×(m / 28))].

[0110] Among them, i represents the complex number field, and exp represents the exponential function with the natural constant e as the base.

[0111] The acquisition process of the other sub-signals except the first sub-signal among the at least two sub-signals mentioned above can refer to the acquisition process of the first sub-signal, and the embodiments of the present application will not be described in detail.

[0112] A22. The signal processing device determines the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals.

[0113] In an embodiment of the present application, the upper sideband component (i.e., part of the upper sideband) and the lower sideband component (i.e., part of the lower sideband) of each sub-signal can be obtained by filtering, and then the correlation between the upper sideband component and the lower sideband component can be determined. In this way, the overall correlation between the upper sideband and the lower sideband can be reflected by the partial correlation between the upper sideband and the lower sideband, reducing the computational complexity of the correlation. For example, the process includes: for each sub-signal in at least two sub-signals, the upper sideband component obtained by filtering the upper sideband component of the sub-signal, the lower sideband component obtained by filtering the lower sideband component of the sub-signal, and the correlation between the upper sideband component and the lower sideband component is used as the correlation between the upper sideband and the lower sideband of the sub-signal. Among them, the upper sideband component and the lower sideband component obtained by filtering are respectively a group of time domain signals in the digital domain. The correlation between the upper sideband component and the lower sideband component can be determined by a preset correlation algorithm.

[0114] Among them, the filtering positions of the upper sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same. That is, the filtering position of the upper sideband component filtering is fixed. The filtering position of the lower sideband component filtering is fixed. The filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering, so that the correlation between the upper sideband component and the lower sideband component can be determined under the same filtering bandwidth, and there is no need to align the upper sideband component and the lower sideband component in bandwidth, thereby reducing the calculation complexity of the correlation.

[0115] The aforementioned process of obtaining the upper sideband component and the lower sideband component can be implemented in the digital domain or in the optical domain. Figure 7 and Figure 8 The two signal processing methods provided in the embodiments of the present application are respectively provided as schematic diagrams of the filtering principle of the signal processing system involved. The signal processing system includes: a coherent receiver 301 and a signal processing device 302. The functions of the coherent receiver 301 and the signal processing device 302 are as described above. Figure 5 and Figure 6 .like Figure 7 As shown, taking the first sub-signal as an example, Figure 7In the embodiment, the upper sideband component and the lower sideband component are obtained by filtering the upper sideband component and the lower sideband component of the first sub-signal in the digital domain (i.e., at the signal processing device). In an optional implementation, the signal processing device can filter the upper sideband and the lower sideband through a digital band-pass filter. The digital band-pass filter is used to allow signals of a specific frequency band to pass through in the digital domain while shielding signals of other frequency bands. Among them, the position of the digital band-pass filter for obtaining the upper sideband component is at f+α0 / 2 of the first signal, and the position of the digital band-pass filter for obtaining the lower sideband component is at f-α0 / 2 of the first signal, where f is the center frequency and α0 is the baud rate of the first signal. For example, the corresponding position of the center frequency of the first signal is 0GHz, and the baud rate is 28GHz. The position of the first digital band-pass filter for filtering the upper sideband component is +14GHz; the position of the second digital band-pass filter for filtering the lower sideband component is -14GHz.

[0116] The frequency range corresponding to the bandwidth range of the first digital bandpass filter and the second digital bandpass filter can be from tens of MHz to hundreds of MHz, as long as the corresponding sideband components are effectively acquired. By sweeping the first sub-signal, the first digital bandpass filter filters the upper sideband components, and the second digital bandpass filter filters the lower sideband components.

[0117] like Figure 8 As shown, taking the first sub-signal as an example, Figure 8 In the embodiment, the first sub-signal is subjected to upper sideband component filtering and lower sideband component filtering in the electrical domain of the coherent receiver to obtain an upper sideband component and a lower sideband component. Accordingly, the signal processing device 302 receives the upper sideband component and the lower sideband component.

[0118] Fig. 9 The embodiment of the present application provides Figure 8 Schematic diagram of filtering principle of signal processing system involved in signal processing method based on . Coherent receiver can filter upper sideband and lower sideband through filter. Among them, the filter used to obtain upper sideband component and the filter used to obtain lower sideband component are both low-pass filters with center frequency at zero frequency. Among them, the filtering rule of low-pass filter is that low-frequency signal can pass normally, while high-frequency signal exceeding the set critical value is blocked or weakened. Fig. 9It is assumed that the signal processing system includes a first coherent receiver 301a and a second coherent receiver 301b, wherein the first coherent receiver 301a includes a first local oscillator laser, a first photodetector and a first filter; and the second coherent receiver 301b includes a second local oscillator laser, a second photodetector and a second filter. The bandwidth of the first filter and the second filter can range from a dozen MHz to several hundred MHz, as long as the corresponding sideband components are effectively acquired, and the first local oscillator laser and the second local oscillator laser have multiple adjustable center frequencies. During the coherent detection process of the optical signal in the first coherent receiver 301a, the first local oscillator laser sweeps the optical signal to locate the upper sideband component, and then the upper sideband component is filtered out by the first low-pass filter after the photoelectric conversion is performed in the first optical detector; during the coherent detection process of the optical signal in the second coherent receiver 301b, the second local oscillator laser sweeps the optical signal to locate the lower sideband component, and then the lower sideband component is filtered out by the second low-pass filter after the photoelectric conversion is performed in the second optical detector.

[0119] Fig. 9 The signal processing system in the filter realizes the filtering of the upper sideband component and the lower sideband component by adjusting the difference between the center frequency of the local oscillator laser and the optical signal. In the first coherent receiver 301a, when the center frequency of the first local oscillator laser is different from the center frequency of the optical signal, the spectrum of the electrical signal obtained by the first optical detector based on the conversion of the optical signal will have an offset relative to the zero-frequency origin, and the first filter is always located at zero frequency, so the frequency near the origin can be filtered out. For example, assuming that the baud rate of the optical signal is 28GHz, when the center frequency of the first local oscillator laser is higher than the center frequency of the optical signal by 14GHz, the spectrum of the obtained electrical signal will have an offset of 14GHz relative to the zero-frequency origin, and the first filter will filter out the upper sideband component. Similarly, when the center frequency of the second local oscillator laser is lower than the center frequency of the optical signal by 14GHz, the second filter will filter out the lower sideband component.

[0120] It is worth noting that there may be other components in the coherent receiver. Fig. 9 The elements are only schematically illustrated.

[0121] A23. The signal processing device obtains the relationship parameters of the first signal by fitting based on at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals.

[0122] The relationship parameter of the first signal is used to reflect the relationship between the correlation between the upper sideband and the lower sideband of the first signal and the frequency deviation. Based on the at least two obtained frequency deviations and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, the relationship parameter of the first signal can be fitted.

[0123] It is worth noting that the more types of frequency offsets loaded in the above steps A21 to A23, the higher the accuracy of the relationship parameters obtained by fitting. For example, the above at least two frequency offsets may include 10 to 30 frequency offsets, and the corresponding correlations obtained may include 10 to 30 correlations.

[0124] For example, the relation parameter is the drop rate, Fig.10 It is a schematic diagram of the fitting result of the drop rate of a first signal provided in an embodiment of the present application. Fig.10 The horizontal axis represents the frequency deviation in GHz, and the vertical axis represents the correlation. Among them, the drop rate can be obtained by introducing different frequency deviations and calculating the corresponding series of correlation values, and then fitting the correlation and frequency deviation values. The relationship between the correlation and the frequency deviation can be expressed by a cubic function. After demonstration, if the relationship between the correlation and the frequency deviation is expressed by other functions such as quadratic function or quartic function, its accuracy is much less than that of the cubic function. Therefore, the cubic function can more accurately reflect the relationship between the correlation and the frequency deviation. Using the cubic function to describe the relationship between the correlation and the frequency deviation can effectively improve the accuracy of the final fitting result.

[0125] For example, the cubic function is the first formula, and the first formula is: y = Ax 3 + Z, where A represents the drop rate, y represents the correlation, x represents the frequency deviation, and Z represents the bias introduced by other inherent factors, which is not zero. For example, the inherent factors include the noise introduced by the transmitter, the noise introduced by the receiver, and / or the resolution of the receiving end (such as a coherent receiver). The obtained at least two frequency deviation values ​​and the corresponding correlation values ​​are used in the first formula y=Ax 3 +Z is used to fit to obtain the relationship curve corresponding to the first formula, and the relationship curve is used to reflect the downward trend of the correlation with the increase of the frequency deviation. A is obtained based on the relationship curve. Fig.10 In the relationship curve obtained by fitting multiple data points, each data point represents a frequency deviation value and a corresponding correlation value. Among them, a frequency deviation value corresponds to a correlation value, which means that the two belong to the same sub-signal. For example, when the frequency deviation is 1 GHz, the correlation is 0.8; when the frequency deviation is 2 GHz, the correlation is 0.7, and the correlation gradually decreases as the frequency deviation increases.

[0126] like Figure 6 As shown, the process of obtaining the relationship parameter of the first signal includes:

[0127] A24. The signal processing device receives at least two sub-signals, where the at least two sub-signals are signals obtained by applying at least two different frequency offsets to the first signal.

[0128] For example, the at least two sub-signals are signals obtained by the coherent receiver 301 by loading at least two different frequency offsets on the first signal. In an optional implementation, the coherent receiver 301 includes a local oscillator laser, and the local oscillator laser has multiple adjustable center frequencies. By changing the center frequency of the local oscillator laser, it is possible to load different frequency offsets on the first optical signal received by the coherent receiver 301, thereby obtaining at least two sub-signals. Correspondingly, the signal processing device receives the at least two sub-signals. For example, in the coherent detection process of the coherent receiver 301, the local oscillator laser sweeps the optical signal to achieve frequency offset loading of the optical signal.

[0129] In an optional example, the structure of the signal processing system can refer to Fig. 9 , during the coherent detection process of the first coherent receiver 301a, the first local oscillator laser sweeps the optical signal to achieve frequency offset loading of the upper sideband component; during the coherent detection process of the second coherent receiver 301b, the second local oscillator laser sweeps the optical signal to achieve frequency offset loading of the lower sideband component. Assuming that the center frequency of the optical signal is T, the baud rate of the optical signal is E, and the frequency offset to be loaded is L, the center frequency of the first local oscillator laser is adjusted to T+L+E / 2, so that the position of the signal spectrum of the electrical signal corresponding to the upper sideband of the optical signal will move forward by L relative to the origin; the center frequency of the second local oscillator laser is adjusted to T+LE / 2, so that the position of the signal spectrum of the electrical signal corresponding to the lower sideband of the optical signal will move forward by L relative to the origin.

[0130] By Fig. 9 Taking the coherent receiver shown in the figure as an example to realize frequency offset loading, assuming that the center frequency of the optical signal is T, the baud rate of the optical signal is 28GHz, and a frequency offset of 1GHz needs to be loaded, the center frequencies of the first local oscillator laser and the second local oscillator laser are adjusted to be "15GHz higher than the center frequency of the optical signal" (i.e., T+15GHz) and "13GHz lower than the center frequency of the optical signal" (i.e., the center frequency is T-13GHz). The interval between the center frequencies of the first local oscillator laser and the second local oscillator laser is 28GHz, which is the baud rate of the optical signal.

[0131] For another example, assuming that the center frequency of the first signal is T and the baud rate is 28 GHz. When the center frequency of the optical signal of the first local oscillator laser is T+14 GHz and the center frequency of the optical signal of the second local oscillator laser is T-14 GHz, the signals filtered out by the upper sideband component and the lower sideband component filtered out by the first filter and the second filter are the electrical signals corresponding to the first signal (i.e., no frequency deviation is loaded, also referred to as the loaded frequency deviation is 0); when the center frequency of the optical signal of the first local oscillator laser is T+15 GHz and the center frequency of the optical signal of the second local oscillator laser is T-13 GHz, the signals filtered out by the upper sideband component and the lower sideband component filtered out by the first filter and the second filter are the electrical signals corresponding to the first signal loaded with a 1 GHz frequency deviation; when the center frequency of the optical signal of the first local oscillator laser is T+16 GHz and the center frequency of the optical signal of the second local oscillator laser is T-12 GHz, the signals filtered out by the upper sideband component and the lower sideband component filtered out by the first filter and the second filter are the electrical signals corresponding to the first signal loaded with a 2 GHz frequency deviation.

[0132] It is worth noting that the aforementioned embodiment only takes the signal processing system including two coherent receivers as an example to illustrate the frequency offset loading in the optical domain. In actual implementation, the signal processing system can also use one coherent receiver or three or four coherent receivers to realize the frequency offset loading. For different numbers of coherent receivers, the method of frequency offset loading by adjusting the center frequency of the local oscillator laser in the coherent receiver should be covered within the protection scope of the embodiments of the present application.

[0133] A25. The signal processing device determines the correlation between the upper sideband of each sub-signal of at least two sub-signals and .

[0134] Step A25 can refer to the aforementioned A22 and will not be elaborated in this embodiment of the present application.

[0135] A26. The signal processing device obtains the relationship parameters of the first signal by fitting based on at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals.

[0136] Step A26 can refer to the aforementioned A23 and will not be elaborated in this embodiment of the present application.

[0137] It is worth noting that, referring to the above Figures 5 to 9, the target signal transmitted in the optical transmission link is an optical signal, and the signal processing device receives a digital signal converted from the optical signal. Since chromatic dispersion in the optical transmission link will cause a certain delay to signals of different frequencies, and the upper and lower sidebands of the same signal correspond to different frequencies, the upper and lower sidebands will produce a time domain offset during the transmission process, which will affect the accuracy of the correlation between the upper and lower sidebands of the same signal determined later, thereby affecting the detection accuracy of the relationship parameters. Therefore, after receiving the digital signal, the signal processing device first performs chromatic dispersion compensation on the received digital signal to obtain a digital signal after chromatic dispersion compensation. Among them, chromatic dispersion compensation refers to compensating the phase of the digital signal. Afterwards, the signal processing device obtains the relationship parameters of the digital signal after chromatic dispersion compensation. That is, before the aforementioned A21 or A24, the signal processing device needs to perform chromatic dispersion compensation on the received digital signal, so as to achieve time calibration of the digital signal, thereby improving the accuracy of the acquired relationship parameters. The chromatic dispersion compensation can be achieved by using a time domain digital filter or a frequency domain digital equalizer to correct the phase of the received signal.

[0138] A3. The signal processing device obtains a first relationship by fitting based on at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired relationship parameters.

[0139] As described in A2 above, for each of the at least three signals, its relationship parameters are obtained. For example, the drop rate of each signal is obtained, still in the form of Fig.10 For example, assuming that the aforementioned at least three signals have a total of N signals, the first formula is adopted: y = Ax 3 +Z to fit the drop rate obtained by N, namely A1, A2, ...A N Furthermore, for each of the at least three signals, its linear signal-to-noise ratio and nonlinear signal-to-noise ratio are obtained.

[0140] Since both linear noise and nonlinear noise will destroy the correlation between the upper and lower sidebands of the signal spectrum. However, linear noise is flat in the spectrum, while nonlinear noise is not flat in the spectrum. Therefore, when there is a frequency offset, the influence of linear noise and nonlinear noise on the correlation between the upper and lower sidebands of the spectrum is also different. Therefore, a binary linear equation can be established to reflect the first relationship between the correlation of the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio and the frequency. For example, the first relationship can be expressed by the following first relationship:

[0141]

[0142] Among them, A represents the relationship parameter, SNR linear Represents the linear signal-to-noise ratio, SNR nonlinearrepresents the nonlinear signal-to-noise ratio, B1 represents the contribution of linear noise to the relationship parameter A, B2 represents the contribution of nonlinear noise to the relationship parameter A, and B3 represents the bias introduced by other inherent factors. For example, the inherent factors include the noise introduced by the transmitter, the noise introduced by the receiver, and / or the resolution of the receiving end (such as a coherent receiver).

[0143] Before fitting, at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained relationship parameter A are known numbers; B1, B2, and B3 are unknown numbers. By fitting at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios (such as the aforementioned N pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios), and the obtained relationship parameters (such as the aforementioned A1, A2, ... A N ) into the first relational expression, B1, B2 and B3 can be obtained by fitting. Substituting the fitted B1, B2 and B3 into the first relational expression, the first relational expression with known coefficients can be obtained.

[0144] S202: The signal processing device obtains a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio, and a signal-to-noise ratio in an optical transmission link.

[0145] In the same optical transmission system, the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal of the optical transmission link are correlated with the signal-to-noise ratio. In the embodiment of the present application, the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the second relationship between the signal-to-noise ratio in the optical transmission link are obtained, so as to determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio of the signal to be measured in the optical transmission link (referred to as the target signal in the embodiment of the present application) based on the second relationship in the subsequent process.

[0146] In an optional manner, the process of obtaining the second relationship includes the following steps:

[0147] B1. The signal processing device determines a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio corresponding to each of at least three signals in an optical transmission link, and obtains at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios. The linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to at least three signals are different.

[0148] Step B1 can refer to the aforementioned step A1, and the present embodiment of the application will not be described in detail. It should be noted that the at least three signals in B1 can be the same as or different from the at least three signals in A1. When the at least three signals in B1 are the same as the at least three signals in A1, the signal acquisition process can be reduced and the processing steps can be simplified.

[0149] B2. The signal processing device obtains the signal-to-noise ratio of each of the at least three signals.

[0150] The signal-to-noise ratio is the overall signal-to-noise ratio. The signal-to-noise ratio of each signal is the signal-to-noise ratio when no frequency deviation is loaded, that is, the signal-to-noise ratio of each signal when the frequency deviation loaded in the optical domain and the digital domain is 0. In an embodiment of the present application, a traditional method for obtaining the signal-to-noise ratio can be used to obtain the signal-to-noise ratio of each of the at least three signals. For example, the signal-to-noise ratio can be determined by using an out-of-band interpolation method or an error vector amplitude calculation method or an SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum or by calculating a theoretical model based on channel parameters or other algorithms. For example, assuming that the aforementioned at least three signals include N signals, as long as the aforementioned method is used to obtain the signal-to-noise ratio for each received signal when the frequency deviation is set to 0, a series of signal-to-noise ratio measurement values ​​can be obtained: SNR meas1 , SNR meas2 ,…SNR measN .

[0151] Fig.11 It is a schematic diagram of the principle of calculating the signal-to-noise ratio of a signal using an out-of-band interpolation method provided in an embodiment of the present application. Fig.11 The spectrum shown can be monitored by a spectrometer. In-band refers to the area occupied by the signal spectrum, that is, within the bandwidth of the signal. Fig.11 As shown, assuming that the target signal is signal X, the in-band of signal X refers to the region with a wavelength range of λ1-α to λ1+α, and the out-band refers to the region outside the bandwidth of the signal. The out-of-band difference method refers to interpolating the in-band noise through the out-of-band noise on both sides of signal X, and determining the signal-to-noise ratio by the in-band noise obtained by interpolation (e.g., linear interpolation) and the total power of the signal and noise at the center frequency of signal X. Assuming that the out-of-band noise is amplified spontaneous emission (ASE) noise, the out-of-band noise of the upper sideband of signal X is ASE1, and the out-of-band noise of the lower sideband is ASE2, then the in-band noise obtained by interpolation is ASE3=(ASE1+ASE2) / 2; assuming that the total power of the signal and noise at the center frequency of signal X is M, then the signal-to-noise ratio is (M-ASE3) / ASE3.

[0152] Fig.12 The present invention provides a schematic diagram of the principle of using an error vector amplitude calculation method to calculate the signal-to-noise ratio of a signal. Fig.12The horizontal axis represents the I path, i.e. the real part, the vertical axis represents the Q path, i.e. the imaginary part, and the circle represents the constellation diagram of the received signal. Assume that the received signal is represented by a signal sequence of length u: [A1, A2, A3, A4…Au], that is, the signal sequence includes u code elements, each code element corresponds to a signal in the received signal, and rk represents the amplitude of the position vector of the kth signal after the constellation diagram of the received signal is restored. 1≤k≤u. sk represents the amplitude of the position vector of the point located on the constellation diagram after the kth signal is judged (for example, for the orthogonal phase shift keying (QPSK) signal, it can be judged as 1+1i, 1-1i, -1+1i, -1-1i. In this case, the vector amplitude is equivalent to the square root of 2). nk represents the amplitude of the noise vector of the kth signal, which can be calculated by connecting the sk end and the rk end. The average power of the signal can be expressed by averaging the square of sk of each code element in u code elements. The average power of the noise can be expressed by averaging the square of nk of each of the u symbols. Then the signal-to-noise ratio can be obtained by dividing the average power of the signal by the average power of the noise.

[0153] The process of determining the signal-to-noise ratio by the SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum may include: determining the signal-to-noise ratio based on a signal-to-noise ratio calculation formula, where the signal-to-noise ratio calculation formula is:

[0154]

[0155] Among them, SNR meas represents the signal-to-noise ratio, that is, the overall signal-to-noise ratio, f represents the frequency, P S Represents the signal power, P N Represents the noise power. meas is the measurement bandwidth of the signal (i.e. the measurement bandwidth of the target signal), E[] represents the average value in the time domain, Indicates that the center frequency is at f c , the correlation between the upper sideband and the lower sideband of the signal with the interval between the maximum frequency and the minimum frequency being α0 (such as the correlation calculated using the upper sideband component and the lower sideband component). The above signal-to-noise ratio calculation formula is derived from the correlation and SNR meas It is derived from the principle of the mutual relationship of Indicates the measurement bandwidth required for monitoring (i.e. the aforementioned measurement bandwidth B meas ), t represents time (also called time domain), It means that under the premise of flat noise spectrum, f cThe noise power at ±α0 / 2 is extended to the total power over the entire measurement bandwidth, and the -1 thereafter is due to the need to remove the noise present in the numerator to comply with the definition of the signal-to-noise ratio.

[0156] For traditional sparse wavelength division multiplexing and point-to-point optical transmission systems, the signal-to-noise ratio determined by the out-of-band interpolation method is relatively accurate. However, with the application of ROADM, the out-of-band ASE noise and the in-band ASE noise may be different, which can easily affect the reliability of the signal-to-noise ratio; in addition, for dense wavelength division multiplexing optical transmission systems, the noise between adjacent channels cannot be effectively read, so the signal-to-noise ratio cannot be effectively obtained. The SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum determines the signal-to-noise ratio, which is not affected by the in-band or out-of-band, nor by the dense wavelength division multiplexing system, and the obtained signal-to-noise ratio is more reliable.

[0157] In the process of obtaining the signal-to-noise ratio by using the error vector amplitude calculation method, the signal needs to be completely decoded, so the entire DSP process needs to be performed, which consumes high power. In addition, for the signal that needs to be analyzed, the corresponding DSP modulation format needs to be configured for different modulation formats, and the versatility for different modulation formats is low. For example, in an optical transmission system, under one modulation format, 1 signal represents 4 bits of data; under another modulation format, 1 signal represents 8 bits of data. The DSP modulation format needs to be configured separately for these two modulation formats. In addition, this method may introduce noise caused by DSP. The SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum determines the signal-to-noise ratio. It does not need to completely decode the signal or perform all DSP processes, which reduces power consumption, does not limit the modulation formats supported by the DSP, and has high flexibility in obtaining the signal-to-noise ratio.

[0158] B3. The signal processing device obtains a second relationship by fitting based on at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired signal-to-noise ratios.

[0159] Since both linear noise and nonlinear noise will affect the overall signal-to-noise ratio (for example, the aforementioned SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum) when there is no frequency deviation, but the nonlinear noise in the upper and lower sideband signals is not completely uncorrelated like Gaussian noise, nor is it as strongly correlated with the signal itself, the nonlinear noise does not contribute to the overall signal-to-noise ratio, but the contribution is not as large as that of linear noise. Therefore, a two-variable first-order equation can be established to reflect the second relationship between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio and the signal-to-noise ratio. For example, the second relationship can be expressed by the following second relationship:

[0160]

[0161] Among them, SNR meas Represents signal-to-noise ratio, SNRlinear Represents the linear signal-to-noise ratio, SNR nonlinear represents the nonlinear signal-to-noise ratio, C1 represents the linear noise to signal-to-noise ratio SNR meas C2 represents the contribution of nonlinear noise to the nonlinear signal-to-noise ratio SNR nonlinear C3 represents the bias introduced by other inherent factors.

[0162] Before fitting, at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained signal-to-noise ratios are known numbers; C1, C2, and C3 are unknown numbers. By substituting at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained signal-to-noise ratios into the second relational expression, C1, C2, and C3 can be obtained by fitting. Substituting the fitted C1, C2, and C3 into the second relational expression, a second relational expression with known coefficients can be obtained.

[0163] S203: The signal processing device detects a target relationship parameter of a target signal received through the optical transmission link.

[0164] The target relationship parameter is the relationship parameter of the target signal. Figures 5 to 9 , the target signal transmitted in the optical transmission link is an optical signal, and the signal processing device receives a digital signal converted from the optical signal. Since in the optical transmission link, chromatic dispersion will cause a certain delay to signals of different frequencies, and the upper and lower sidebands of the target signal correspond to different frequencies, during the transmission process, the upper and lower sidebands will produce a time domain offset, which will affect the accuracy of the correlation between the upper and lower sidebands of the determined target signal, thereby affecting the detection accuracy of the target relationship parameters. Therefore, after receiving the digital signal, the signal processing device performs chromatic dispersion compensation on the received digital signal to obtain a digital signal after chromatic dispersion compensation. Afterwards, the signal processing device detects the relationship parameters of the digital signal after chromatic dispersion compensation to obtain the target relationship parameters. In this way, the time calibration of the digital signal is achieved, thereby improving the accuracy of the acquired target relationship parameters.

[0165] S204: The signal processing device obtains a target signal-to-noise ratio of the target signal.

[0166] In an embodiment of the present application, the signal processing device can obtain the signal-to-noise ratio of the target signal by adopting a traditional method for obtaining the signal-to-noise ratio to obtain the target signal-to-noise ratio. For example, the target signal-to-noise ratio can be determined by using an out-of-band interpolation method or an error vector amplitude calculation method or an SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum or by a theoretical model calculation or other algorithms based on channel parameters. The process of obtaining the target signal-to-noise ratio can refer to the process of obtaining the signal-to-noise ratio of the signal in the aforementioned step B2.

[0167] It is worth noting that the signal processing device can use the same signal-to-noise ratio acquisition method to obtain the signal-to-noise ratio of each of the at least three signals and the target signal-to-noise ratio, which can offset the interference introduced by other inherent factors in the optical transmission link, thereby obtaining more accurate linear signal-to-noise ratio and nonlinear signal-to-noise ratio in subsequent processes.

[0168] Optionally, the signal processing device uses an SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum to obtain the target signal-to-noise ratio. The accuracy of obtaining the target signal-to-noise ratio using this method is high, and the calculation is relatively simple.

[0169] S205: The signal processing device determines a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal based on the target relationship parameter, the target signal-to-noise ratio, the first relationship, and the second relationship.

[0170] Referring to the aforementioned steps A3 and B3, the first relationship is represented by a first relational expression in which the independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and the dependent variable is the relationship parameter. The second relationship is represented by a second relational expression in which the independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and the dependent variable is the signal-to-noise ratio. The signal processing device substitutes the target relationship parameters into the first relational expression, and substitutes the target signal-to-noise ratio into the second relational expression, that is, the known numbers are the target relationship parameters and the target signal-to-noise ratio, and the unknown numbers are the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal. The linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal can be obtained by solving a set of two-variable linear equations.

[0171] In the embodiment of the present application, the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal are obtained by solving equations. The obtaining method is simple and fast, and the calculation efficiency is high.

[0172] It is worth noting that the first relationship is established by using the correlation and the relationship between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio; the second relationship is established by using the relationship between the signal-to-noise ratio and the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio; therefore, the first relationship can be transformed based on the correlation and the relationship between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio to obtain other forms of relationship; the second relationship can be transformed based on the relationship between the signal-to-noise ratio and the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio to obtain other forms of relationship. As long as a set of two-variable linear equations with the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio as variables can be established based on the acquired relationship, this set of two-variable linear equations can be used to realize the joint monitoring of the linear and nonlinear signal-to-noise ratios of the received target signal.

[0173] In another implementation, since linear noise and linear signal-to-noise ratio have a negative correlation (e.g., an inverse correlation), and nonlinear noise and nonlinear signal-to-noise ratio have a negative correlation (e.g., an inverse correlation), the first relationship mentioned above can also be established by using the correlation and the relationship between linear noise and nonlinear noise; the second relationship is established by using the relationship between the signal-to-noise ratio and linear noise and nonlinear noise. Based on the acquired relationship, a set of two-variable linear equations with linear noise and nonlinear noise as variables is established, and this set of two-variable linear equations is used to realize joint monitoring of linear and nonlinear noise for the received target signal, and then the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio are acquired based on the acquired linear noise and nonlinear noise.

[0174] The operation and reconstruction of signals on an optical transmission link depend on the quality of the optical transmission link, and an accurate optical signal-to-noise ratio can reflect the quality of the optical transmission link. The optical signal-to-noise ratio actually includes a linear signal-to-noise ratio caused by an optical amplifier and the like and a nonlinear signal-to-noise ratio caused by the optical transmission link itself (such as an optical fiber). The embodiment of the present application refines the granularity of obtaining the signal-to-noise ratio by effectively distinguishing between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the target signal. In practical applications, the optical transmission system can be monitored and maintained based on the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the acquired target signal. For example, after the linear signal-to-noise ratio corresponding to the target signal is greater than the linear signal-to-noise ratio threshold, the signal processing device determines that there is a risk of failure in the optical amplifier in the optical transmission link upstream of the signal processing device. The signal processing device can issue a first alarm message, indicating that there is a risk of failure in the optical amplifier in the optical transmission link upstream of the signal processing device, so as to facilitate the staff to repair or replace the optical amplifier. For another example, after the nonlinear signal-to-noise ratio corresponding to the target signal is greater than the nonlinear signal-to-noise ratio threshold, the signal processing device determines that there is a failure risk in the optical transmission link (such as an optical fiber) upstream of the signal processing device. The signal processing device may issue a second alarm message to indicate that there is a failure risk in the optical transmission link upstream of the signal processing device, so as to facilitate the staff to repair or replace the optical transmission link.

[0175] It should be noted that, in the above embodiments, the signal processing device is introduced to perform upper sideband component filtering and lower sideband component filtering (refer to Figure 7 Corresponding explanation), the signal processing device performs frequency offset loading (refer to Figure 5 Corresponding explanation); the coherent receiver performs upper sideband component filtering and lower sideband component filtering (refer to Figure 8 and Fig. 9 Corresponding explanation), the coherent receiver performs frequency offset loading (refer to Figure 6 and Fig. 9Corresponding explanations) and other processes involved in several signal processing methods. In actual implementation, the implementation of the signal processing method may include the following combinations: the signal processing device performs upper sideband component filtering and lower sideband component filtering, and the signal processing device performs frequency offset loading; or, the coherent receiver performs upper sideband component filtering and lower sideband component filtering, and the coherent receiver performs frequency offset loading; or, the signal processing device performs upper sideband component filtering and lower sideband component filtering, and the coherent receiver performs frequency offset loading; or, the coherent receiver performs upper sideband component filtering and lower sideband component filtering, and the signal processing device performs frequency offset loading. Any method obtained by simple deformation based on the aforementioned combination should be included in the protection scope of the present application.

[0176] In summary, the embodiments of the present application establish a first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameter in the optical transmission link, and a second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link according to the different characteristics of the flat linear noise spectrum and the non-flat nonlinear noise spectrum. Based on these two relationships, the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the target signal are determined using the target relationship parameters and the target signal-to-noise ratio actually obtained, thereby achieving effective distinction between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal.

[0177] Furthermore, the embodiment of the present application can simultaneously acquire the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal, and the acquisition efficiency of the signal-to-noise ratio is high, which facilitates the staff to conduct a comprehensive and effective analysis of the transmission quality of the optical transmission link.

[0178] Furthermore, the signal processing method provided in the embodiment of the present application does not limit the modulation format supported by the DSP, and can support the monitoring of the linear signal-to-noise ratio and nonlinear signal-to-noise ratio of signals of different modulation formats, thereby improving the monitoring flexibility.

[0179] As described in the aforementioned step A2, the nonlinear signal-to-noise ratio can also be obtained by adding a pilot signal to the signal transmitted in the optical transmission link, but this will sacrifice spectrum efficiency and system flexibility. In the embodiment of the present application, once the first relationship and the second relationship are obtained, the linear noise and the nonlinear noise can be obtained by solving a set of two-variable linear equations, and the signal-to-noise ratio is highly flexible, reducing the impact on spectrum efficiency and system flexibility.

[0180] refer to Fig.12 When the traditional error vector amplitude calculation method is used to calculate the signal-to-noise ratio of a signal, the signal needs to be completely restored, and the complexity of obtaining the signal-to-noise ratio of the signal is relatively high. However, the embodiment of the present application obtains the signal-to-noise ratio by solving a set of two-variable linear equations, without the need to completely restore the signal, thereby effectively reducing the complexity of obtaining the signal-to-noise ratio.

[0181] It should be noted that the sequence of steps of the signal processing method provided in the embodiment of the present application can be appropriately adjusted, and the steps can also be increased or decreased accordingly according to the situation. Any technical personnel familiar with the technical field can easily think of the change method within the technical scope disclosed in the present application, and it should be covered within the protection scope of the present application. For example, the aforementioned S201 and S202 can be obtained when the optical transmission system is networked (or after the optical transmission system is initialized), and then S203 to S205 are executed during the subsequent signal transmission of the optical transmission link; or, S201 to S205 are executed during the signal transmission of the optical transmission link. Optionally, the signal processing device can also periodically execute S201 and S202, so that the latest first relationship and second relationship can be obtained, ensuring that the monitored linear signal-to-noise ratio and nonlinear signal-to-noise ratio are updated as the quality of the optical transmission link changes, thereby improving the accuracy of the determined linear signal-to-noise ratio and nonlinear signal-to-noise ratio.

[0182] Fig.13 is a schematic diagram of the structure of a signal processing device 40 provided in an embodiment of the present application, such as Fig.13 As shown, the device 40 includes:

[0183] The first relationship acquisition module 401 is used to acquire a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a relationship parameter in an optical transmission link, wherein the relationship parameter is used to reflect the relationship between the correlation of an upper sideband and a lower sideband of a signal in the optical transmission link and a frequency deviation; the second relationship acquisition module 402 is used to acquire a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a signal-to-noise ratio in the optical transmission link; the parameter acquisition module 403 is used to acquire a target relationship parameter of a target signal received through the optical transmission link; the signal-to-noise ratio acquisition module 404 is used to acquire a target signal-to-noise ratio of the target signal; and the determination module 405 is used to determine a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship.

[0184] In summary, the present application establishes a first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameters in the optical transmission link through a first relationship acquisition module, and establishes a second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link through a second relationship acquisition module. The determination module determines the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the target signal based on these two relationships, using the actually obtained target relationship parameters and target signal-to-noise ratio, thereby achieving effective distinction between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal.

[0185] In an optional example, the first relationship is represented by a first relational equation in which the independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and the dependent variable is the relationship parameter; the second relationship is represented by a second relational equation in which the independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and the dependent variable is the signal-to-noise ratio; the determination module 405 is used to: substitute the target relationship parameter into the first relational equation, substitute the target signal-to-noise ratio into the second relational equation, and obtain the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal by solving a set of two-variable linear equations.

[0186] In an optional example, the target signal received through the optical transmission link is an optical signal, and the parameter acquisition module 403 is used to: perform chromatic dispersion compensation on a digital signal, the digital signal is converted from the optical signal; detect the relationship parameters of the digital signal after chromatic dispersion compensation to obtain the target relationship parameters.

[0187] Fig.14 4 is a schematic diagram of the structure of a first relationship acquisition module 401 provided in an embodiment of the present application. Fig.14 As shown, the first relationship acquisition module 401 includes:

[0188] The determination submodule 4011 is used to determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are different; the acquisition submodule 4012 is used to obtain the relationship parameters of each of the at least three signals; the fitting submodule 4013 is used to fit the first relationship based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the obtained relationship parameters.

[0189] Optionally, the acquisition submodule 4012 is used to: load at least two different frequency offsets on the first signal in the digital domain to obtain at least two sub-signals, or receive at least two sub-signals, the at least two sub-signals are signals obtained by loading at least two different frequency offsets on the first signal, and the first signal is any one of the at least three signals; determine the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals; based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, fit the relationship parameters of the first signal.

[0190] Further, the acquisition submodule 4012 is used to: for each of the at least two sub-signals, obtain an upper sideband component obtained by filtering the upper sideband component of the sub-signal, obtain a lower sideband component obtained by filtering the lower sideband component of the sub-signal, and use the correlation between the upper sideband component and the lower sideband component as the correlation between the upper sideband and the lower sideband of the sub-signal; wherein, the filtering positions of the upper sideband component filtering of at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband component filtering of at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering.

[0191] In an optional example, the second relationship acquisition module 402 is used to: determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of at least three signals in the optical transmission link, and obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to at least three signals are different; obtain the signal-to-noise ratio of each of the at least three signals; and fit the second relationship based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, and the obtained signal-to-noise ratios.

[0192] Optionally, at least three signals are different in at least one of the following parameters: transmission power, amplification factor of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

[0193] It is worth noting that the relationship parameter may be a drop rate, which is a drop rate at which the correlation between the upper sideband and the lower sideband of a signal in an optical transmission link drops as the frequency offset increases.

[0194] Fig.15 It is a possible basic hardware architecture of the computer device provided in the embodiment of the present application. The computer device may be the aforementioned signal processing device. Fig.15 , the computer device 500 includes a processor 501 , a memory 502 , a communication interface 503 and a bus 504 .

[0195] In the computer device 500, the number of processors 501 may be one or more. Fig.15 Only one of the processors 501 is shown. Optionally, the processor 501 may be a central processing unit (CPU). If the computer device 500 has multiple processors 501, the types of the multiple processors 501 may be different or the same. Optionally, the multiple processors 501 of the computer device 500 may also be integrated into a multi-core processor.

[0196] The memory 502 stores computer instructions and data; the memory 502 may store computer instructions and data required to implement the signal processing method provided in the present application, for example, the memory 502 stores instructions for implementing the steps of the signal processing method. The memory 502 may be any one or any combination of the following storage media: non-volatile memory (e.g., read-only memory (ROM), solid-state drive (SSD), hard disk (HDD), optical disk), volatile memory.

[0197] The communication interface 503 may be any one or any combination of the following devices: a network interface (eg, an Ethernet interface), a wireless network card, or other device with a network access function.

[0198] The communication interface 503 is used for the computer device 500 to perform data communication with other computer devices or terminals.

[0199] The bus 504 can connect the processor 501 to the memory 502 and the communication interface 503. In this way, the processor 501 can access the memory 502 through the bus 504, and can also use the communication interface 503 to exchange data with other computer devices or terminals.

[0200] In the present application, the computer device 500 executes the computer instructions in the memory 502, so that the computer device 500 implements the signal processing method provided in the present application, or enables the computer device 500 to deploy a database system.

[0201] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions, and the above instructions can be executed by a processor of a server to complete the signal processing method shown in various embodiments of the present application. For example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0202] Fig.16 is a schematic diagram of the structure of a signal processing system 60 provided in an embodiment of the present application, such as Fig.16 As shown, the signal processing system 60 includes: a coherent receiver 601 and a signal processing device 602 provided in an embodiment of the present application. The signal processing device 602 may be the aforementioned signal processing device 40, or the aforementioned computer device 500. The structure of the signal processing system 60 may refer to the aforementioned Figures 5 to 9 The structure of any signal processing system described above.

[0203] The coherent receiver 601 is used to receive an optical signal from an optical transmission link, convert the received optical signal into a digital signal, and send the converted digital signal to a signal processing device. The use of a coherent receiver to acquire an optical signal can retain the complete information of the optical signal, making it easier for the signal processing device to perform chromatic dispersion compensation and / or frequency offset loading. In actual implementation, the coherent receiver can also be replaced by other types of receivers, as long as the complete information of the optical signal can be acquired through the other types of reception.

[0204] Further, the coherent receiver 601 is used to download the optical signal from the optical transmission link through coherent light, and convert the downloaded optical signal into two optical signals with mutually perpendicular polarization directions, and then convert them into two digital signals, so as to send the two digital signals to the signal processing device. Accordingly, the signal processing device 602 processes the two digital signals respectively to obtain the linear signal-to-noise ratio and nonlinear signal-to-noise ratio corresponding to each digital signal. The aforementioned S201 to S205 are described by taking one of the two digital signals as an example. In actual implementation, the aforementioned S201 to S205 are performed on both digital signals.

[0205] The coherent receiver 601 may have various structures. The embodiments of the present application are described by taking the following two optional implementations as examples.

[0206] Fig.17 is a structural diagram of a signal processing system 60 provided in an embodiment of the present application, wherein a coherent receiver 601 includes:

[0207] The local oscillator laser 6011 is used to generate coherent light and input the coherent light into the polarization beam splitter 6012. The center frequency of the local oscillator laser 6011 is the same as the center frequency of the target signal to be detected, so that the target signal can be downloaded under the action of the local oscillator laser 6011. For example, Figure 4 As shown, if the target signal to be downloaded is signal X, the center wavelength of the local oscillator laser 6011 is the same as the center wavelength of signal X; if the target signal to be downloaded is signal Y, the center wavelength of the local oscillator laser 6011 is the same as the center wavelength of signal Y.

[0208] The polarization beam splitter 6012 is used to split the received optical signal (ie, the optical signal transmitted by the optical transmission link) into a first polarized light and a second polarized light perpendicular to each other, and to split the coherent light into a third polarized light and a fourth polarized light perpendicular to each other.

[0209] Two 90° mixers 6013, wherein one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light. The first polarized light and the third polarized light have the same polarization direction, and the second polarized light and the fourth polarized light have the same polarization direction; or, the first polarized light and the third polarized light have different polarization directions, and the second polarized light and the fourth polarized light have different polarization directions. For example, the first polarized light and the third polarized light are both x-polarized light, and the second polarized light and the fourth polarized light are both y-polarized light.

[0210] The photodetector 6014 is used to convert the optical signals output by the two 90° mixers into analog currents. The photodetector 6014 may be a balanced photodetector. The use of the balanced photodetector 6014 may achieve noise cancellation and reduce the noise in the output analog current. The photodetector outputs 4 real signals, namely, an x-polarized I-signal (i.e., real part), an x-polarized Q-signal (i.e., imaginary part), a y-polarized I-signal, and a y-polarized Q-signal.

[0211] The filter 6015 is used to filter the analog current to obtain an electrical signal corresponding to the target signal. Figure 4 , multiple signals with different central wavelengths may be transmitted on the optical transmission link, and the signal that the signal processing system actually needs to monitor may be only one target signal among the multiple signals, so the target signal needs to be processed in a targeted manner. Assuming that the target signal is X, the filter 6015 can filter out the electrical signal corresponding to the target signal X from the analog current corresponding to the multiple signals. The filter 6015 outputs 4 real signals, namely, the filtered x-polarized I signal, the filtered x-polarized Q signal, the filtered y-polarized I signal, and the filtered y-polarized Q signal.

[0212] The analog-to-digital converter 6016 is used to convert the electrical signal corresponding to the target signal into a digital signal. For example, the analog-to-digital converter 6016 obtains a digital signal by sampling the electrical signal corresponding to the target signal. The analog-to-digital converter 6016 is also used to input the converted digital signal into the signal processing device 602. The analog-to-digital converter 6016 outputs two complex signals, namely an x-polarization signal and a y-polarization signal. Among them, the x-polarization signal is obtained by sampling a complex signal composed of a filtered x-polarization I signal and a filtered x-polarization Q signal, and the y-polarization signal is obtained by sampling a complex signal composed of a filtered y-polarization I signal and a filtered y-polarization Q signal.

[0213] Accordingly, the signal processing device 602 receives two complex signals, namely, an x-polarization signal and a y-polarization signal. The above S201 to S205 are described by taking one of the x-polarization signal and the y-polarization signal as an example. In actual implementation, the above S201 to S205 are performed on both the x-polarization signal and the y-polarization signal.

[0214] It is worth noting that the aforementioned coherent receiver 601 may also have other structures. For example, the aforementioned optical detector 6014 may be replaced by other optical detectors. The aforementioned two 90° mixers may be replaced by other types of mixers, such as one mixer.

[0215] As mentioned above, the digital signal of the analog-to-digital converter 6016 input signal processing device 602 is obtained by converting the entire target signal. If it is necessary to obtain the upper sideband component and the lower sideband component of the digital signal corresponding to the target signal, it is necessary to perform upper sideband component filtering and lower sideband component filtering in the digital domain. Fig.18 6 is a schematic diagram of the structure of another signal processing system 60 provided in an embodiment of the present application. The signal processing device 602 includes: a first digital bandpass filter 6021, which is used to filter the upper sideband component of the received signal. A second digital bandpass filter 6022 is used to filter the lower sideband component of the received signal. The function of the first digital bandpass filter 6021 in the signal processing device 602 can be referred to Figure 7 The function of the first digital bandpass filter in the signal processing device 602 and the function of the second digital bandpass filter 6022 in the signal processing device 602 can refer to Figure 7 The function of the second digital bandpass filter in the embodiment of the present application will not be described in detail.

[0216] Fig.19 6 is a schematic diagram of the structure of another signal processing system 60 provided in an embodiment of the present application. The system 60 also includes: an optical splitter 603, the number of coherent receivers 601 is 2, the optical splitter 603 is used to receive an optical signal from an optical transmission link, and divide the received optical signal into two optical signals, which are respectively input into two coherent receivers 601, one of the two coherent receivers 601 is used for upper sideband component filtering, and the other coherent receiver 601 is used for lower sideband component filtering. The function of the coherent receivers used for upper sideband component filtering in the two coherent receivers 601 can be referred to Fig. 9 The function of the first filter in the coherent receiver for filtering the lower sideband component can be referred to Fig. 9 The function of the second filter in .

[0217] Fig. 206 is a schematic diagram of the structure of a signal processing system 60 provided in an embodiment of the present application. Each coherent receiver 601 includes: a local oscillator laser 6011 for generating coherent light and inputting the coherent light into a polarization beam splitter 6012 .

[0218] The polarization beam splitter 6012 is used to split the received optical signal (ie, the optical signal transmitted by the beam splitter 603) into a first polarized light and a second polarized light that are perpendicular to each other, and to split the coherent light into a third polarized light and a fourth polarized light that are perpendicular to each other.

[0219] Two 90° mixers 6013 , wherein one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light.

[0220] The optical detector 6014 is used to convert the optical signals output by the two 90° mixers into analog currents. The optical detector 6014 may be a balanced optical detector.

[0221] The low-pass filter 6017 is used to filter the analog current to obtain the electrical signal of the corresponding sideband component. For example, the low-pass filter 6017 in the coherent receiver for filtering the upper sideband component is used to filter the analog current to obtain the electrical signal of the upper sideband component; the low-pass filter 6017 in the coherent receiver for filtering the lower sideband component is used to filter the analog current to obtain the electrical signal of the lower sideband component. Optionally, the low-pass filter 6017 is a narrowband filter.

[0222] The analog-to-digital converter 6018 is used to convert the electrical signal corresponding to the sideband component into a digital signal.

[0223] The aforementioned filter 6015 needs to filter out the complete target signal from the received signal, and its bandwidth is relatively wide. Accordingly, the analog-to-digital converter 6016 is a high-speed analog-to-digital converter to realize the effective conversion of the electrical signal corresponding to the target signal to the digital signal, that is, the analog-to-digital converter 6016 is an analog-to-digital converter with a relatively high rate and a relatively large processing bandwidth. Since the low-pass filter 6017 only needs to filter out part of the signal of the target signal, it is a narrow-band filter, and the analog-to-digital converter 6018 is an analog-to-digital converter with a relatively low rate and a relatively small processing bandwidth, then the analog-to-digital converter 6018 is relatively low in rate relative to the aforementioned analog-to-digital converter 6016, and it can be a low-speed analog-to-digital converter. The use of a low-speed analog-to-digital converter can save manufacturing costs.

[0224] Referring to the aforementioned step B2, if the signal-to-noise ratio is determined by the SNR monitoring method based on the correlation between the upper and lower sidebands of the signal spectrum, the overall signal-to-noise ratio SNR is obtained. meas When the total power of the signal and noise in the measurement bandwidth needs to be monitored, if the signal processing system adopts the above Fig. 20In the structure shown, since the two coherent receivers 601 only obtain the sideband components of the target signal and do not obtain the complete target signal, the signal processing device cannot determine the total power of the signal and noise in the measurement bandwidth based on the digital signals output by the two coherent receivers 601. An additional power measurement device is required to obtain the total power of the signal and noise in the measurement bandwidth.

[0225] Fig.21 6 is a schematic diagram of the structure of another signal processing system 60 provided in an embodiment of the present application. The system further includes: a power measuring device 604, which is used to receive an optical signal from an optical transmission link and measure the power of a target signal in the optical signal.

[0226] Fig. 22 60 is a schematic diagram of the structure of another signal processing system 60 provided in an embodiment of the present application. The power measurement device 604 includes:

[0227] The local oscillator laser 6011 is used to generate coherent light and input the coherent light into the polarization beam splitter 6012 .

[0228] The polarization beam splitter 6012 is used to split the received optical signal into a first polarized light and a second polarized light that are perpendicular to each other, and to split the coherent light into a third polarized light and a fourth polarized light that are perpendicular to each other.

[0229] There are two 90° mixers 6013, one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light.

[0230] The optical detector 6014 is used to convert the optical signals output by the two 90° mixers into analog currents. For example, the optical detector 6014 may be a balanced optical detector.

[0231] The filter 6015 is used to filter the analog current to obtain an electrical signal corresponding to the target signal. Its function is as mentioned above. Fig.17 The function of filter 6015.

[0232] The analog-to-digital converter 6018 is used to convert the electrical signal corresponding to the target signal into a digital signal.

[0233] The power measurement module 6041 is used to measure the power of the received digital signal.

[0234] Figures 18 to 22 The functions of the local oscillator laser 6011, polarization beam splitter 6012, 90° mixer 6013, photodetector 6014, filter 6015, and analog-to-digital converter 6016 can all be referred to. Fig.17 The functions of the corresponding modules in the present application will not be described in detail.

[0235] Among them, the aforementioned Figures 17 to 22 The local oscillator laser 6011 in the embodiment can have multiple adjustable center frequencies. The center frequency is adjustable, so that target signals with different center frequencies can be detected (also called positioning the target signal). Figure 4 As shown, the local oscillator laser 6011 can download signal X by adjusting the central wavelength to be the same as the central wavelength of signal X; the local oscillator laser 6011 can also download signal Y by adjusting the central wavelength to be the same as the central wavelength of signal Y. In this way, one local oscillator laser 6011 can download signals with different central wavelengths, realize compatible detection of signals with different wavelengths, reduce the manufacturing cost of the signal processing system, and improve the flexibility of the system.

[0236] For further reference, Fig. 9 The adjustable center frequency of the local oscillator laser 6011 can realize the loading of frequency deviation and / or filtering of upper sideband components and lower sideband components in the optical domain.

[0237] It is worth noting that the optical signal in the optical transmission link detected in the aforementioned embodiment is an optical signal derived from an optical splitter, and the optical splitter is installed in the optical transmission link. The optical power of the optical signal derived from the optical splitter accounts for a small proportion of the optical power of the optical signal transmitted by the optical transmission link, and does not affect the normal transmission of the optical signal in the optical transmission link. For example, the ratio of the optical power of the optical signal derived from the optical splitter to the optical power of the optical signal transmitted by the optical transmission link is 1:99.

[0238] The signal-to-noise ratio in the embodiments of the present application refers to the optical signal-to-noise ratio, the linear signal-to-noise ratio refers to the linear optical signal-to-noise ratio, the nonlinear signal-to-noise ratio refers to the nonlinear optical signal-to-noise ratio, and the center frequency of the local oscillator laser refers to the center frequency of the coherent light output by the local oscillator laser. The aforementioned embodiments are all described by taking the position of the filter at zero frequency as an example, but in actual implementation, the position of the filter can be set according to actual needs. When the signal processing device provided in the above embodiments executes the signal processing method, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the signal processing device provided in the above embodiments belongs to the same concept as the signal processing method embodiment. The specific implementation process is detailed in the method embodiment, which will not be repeated here.

[0239] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0240] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A signal processing method, characterized in that: The method comprises: Acquire a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio, and a relationship parameter in an optical transmission link, wherein the relationship parameter is used to reflect a relationship between a correlation between an upper sideband and a lower sideband of a signal in the optical transmission link and a frequency deviation; Obtaining a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio, and a signal-to-noise ratio in an optical transmission link; Acquiring a target relationship parameter, wherein the target relationship parameter is a relationship parameter of a target signal received through the optical transmission link; Acquire a target signal-to-noise ratio, where the target signal-to-noise ratio is a signal-to-noise ratio of the target signal; Based on the target relationship parameter, the target signal-to-noise ratio, the first relationship, and the second relationship, a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal are determined.

2. The method according to claim 1, characterized in that The first relationship is represented by a first relationship equation with the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio as independent variables and the relationship parameter as dependent variable, and the second relationship is represented by a second relationship equation with the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio as independent variables and the signal-to-noise ratio as dependent variable, The determining, based on the target relationship parameter, the target signal-to-noise ratio, the first relationship, and the second relationship, a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal includes: Substitute the target relationship parameter into the first relationship formula, substitute the target signal-to-noise ratio into the second relationship formula, and obtain the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal by solving a set of two-variable linear equations.

3. The method according to claim 1 or 2, characterized in that: The target signal received through the optical transmission link is an optical signal, and acquiring the target relationship parameter of the target signal received through the optical transmission link includes: Performing chromatic dispersion compensation on a digital signal, wherein the digital signal is obtained by converting the optical signal; The relationship parameters of the digital signal after chromatic dispersion compensation are detected to obtain the target relationship parameters.

4. The method according to any one of claims 1 or 2, characterized in that: The step of obtaining a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio, and a relationship parameter in an optical transmission link includes: Determine a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio corresponding to each of at least three signals in the optical transmission link to obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, wherein the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different; obtaining a relationship parameter of each of the at least three signals; The first relationship is obtained by fitting based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired relationship parameters.

5. The method according to claim 4, characterized in that The obtaining of the relationship parameter of each of the at least three signals comprises: In the digital domain, respectively apply at least two different frequency offsets to the first signal to obtain at least two sub-signals, or receive at least two sub-signals, wherein the at least two sub-signals are signals obtained by applying at least two different frequency offsets to the first signal, and the first signal is any one of the at least three signals; determining a correlation between an upper sideband and a lower sideband of each of the at least two sub-signals; Based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, the relationship parameters of the first signal are obtained by fitting.

6. The method according to claim 5, characterized in that The determining of the correlation between the upper sideband and the lower sideband of each sub-signal of at least two sub-signals comprises: For each of the at least two sub-signals, obtain an upper sideband component obtained by filtering the upper sideband component of the sub-signal, obtain a lower sideband component obtained by filtering the lower sideband component of the sub-signal, and use the correlation between the upper sideband component and the lower sideband component as the correlation between the upper sideband and the lower sideband of the sub-signal; Among them, the filtering positions of the upper sideband component filtering of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband component filtering of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering.

7. The method according to claim 1 or 2, characterized in that: The obtaining of the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link comprises: Determine a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio corresponding to each of at least three signals in the optical transmission link to obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, wherein the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different; Obtaining a signal-to-noise ratio of each of the at least three signals; The second relationship is obtained by fitting based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired signal-to-noise ratios.

8. The method according to claim 4, characterized in that The at least three signals are different in at least one of the following parameters: transmission power, amplification factor of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

9. The method according to claim 1 or 2, characterized in that: The relationship parameter is a drop rate, which is a drop rate at which the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link decreases as the frequency offset increases.

10. A signal processing device, characterized in that: The device comprises: A first relationship acquisition module, used to acquire a first relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio, and a relationship parameter in an optical transmission link, wherein the relationship parameter is used to reflect the relationship between the correlation of an upper sideband and a lower sideband of a signal in the optical transmission link and a frequency deviation; A second relationship acquisition module, used to acquire a second relationship between a linear signal-to-noise ratio, a nonlinear signal-to-noise ratio and a signal-to-noise ratio in an optical transmission link; A parameter acquisition module, used to acquire a target relationship parameter, wherein the target relationship parameter is a relationship parameter of a target signal received through the optical transmission link; A signal-to-noise ratio acquisition module, used to acquire a target signal-to-noise ratio, where the target signal-to-noise ratio is the signal-to-noise ratio of the target signal; A determination module is used to determine a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal based on the target relationship parameter, the target signal-to-noise ratio, the first relationship, and the second relationship.

11. The device according to claim 10, characterized in that The first relationship is represented by a first relationship equation with the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio as independent variables and the relationship parameter as dependent variable, and the second relationship is represented by a second relationship equation with the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio as independent variables and the signal-to-noise ratio as dependent variable, The determining module is used to: Substitute the target relationship parameter into the first relationship formula, substitute the target signal-to-noise ratio into the second relationship formula, and obtain the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal by solving a set of two-variable linear equations.

12. The device according to claim 10 or 11, characterized in that The target signal received through the optical transmission link is an optical signal, and the parameter acquisition module is used to: Performing chromatic dispersion compensation on a digital signal, wherein the digital signal is obtained by converting the optical signal; The relationship parameters of the digital signal after chromatic dispersion compensation are detected to obtain the target relationship parameters.

13. The device according to claim 10 or 11, characterized in that The first relationship acquisition module includes: A determination submodule, used to determine a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio corresponding to each of the at least three signals in the optical transmission link, to obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, wherein the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different; An acquisition submodule, used to acquire a relationship parameter of each of the at least three signals; A fitting submodule is used to fit the first relationship based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired relationship parameters.

14. The device according to claim 13, characterized in that The acquisition submodule is used to: In the digital domain, respectively apply at least two different frequency offsets to the first signal to obtain at least two sub-signals, or receive at least two sub-signals, wherein the at least two sub-signals are signals obtained by applying at least two different frequency offsets to the first signal, and the first signal is any one of the at least three signals; determining a correlation between an upper sideband and a lower sideband of each of the at least two sub-signals; Based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, the relationship parameters of the first signal are obtained by fitting.

15. The device according to claim 14, characterized in that The acquisition submodule is used to: For each of the at least two sub-signals, obtain an upper sideband component obtained by filtering the upper sideband component of the sub-signal, obtain a lower sideband component obtained by filtering the lower sideband component of the sub-signal, and use the correlation between the upper sideband component and the lower sideband component as the correlation between the upper sideband and the lower sideband of the sub-signal; Among them, the filtering positions of the upper sideband component filtering of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband component filtering of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering.

16. The device according to claim 10 or 11, characterized in that The second relationship acquisition module is used to: Determine a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio corresponding to each of at least three signals in the optical transmission link to obtain at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios, wherein the linear signal-to-noise ratios and nonlinear signal-to-noise ratios corresponding to the at least three signals are all different; Obtaining a signal-to-noise ratio of each of the at least three signals; The second relationship is obtained by fitting based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired signal-to-noise ratios.

17. The device according to claim 13, characterized in that The at least three signals are different in at least one of the following parameters: transmission power, amplification factor of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

18. The device according to claim 10 or 11, characterized in that The relationship parameter is a drop rate, which is a drop rate at which the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link decreases as the frequency offset increases.

19. A signal processing system, characterized in that: The signal processing system comprises: a coherent receiver and a signal processing device as claimed in any one of claims 10 to 17; The coherent receiver is used to receive an optical signal from an optical transmission link, convert the received optical signal into a digital signal, and send the converted digital signal to the signal processing device.

20. The system according to claim 19, characterized in that The coherent receiver comprises: Local oscillator laser, used to generate coherent light; A polarization beam splitter, used to split an optical signal transmitted by an optical transmission link into a first polarized light and a second polarized light perpendicular to each other, and to split the coherent light into a third polarized light and a fourth polarized light perpendicular to each other; Two 90° mixers, wherein one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light; A photodetector, used for converting the optical signals output by the two 90° mixers into analog currents; A filter, used for filtering the analog current to obtain an electrical signal corresponding to the target signal; The analog-to-digital converter is used to convert the electrical signal corresponding to the target signal into a digital signal.

21. The system according to claim 20, characterized in that The signal processing device comprises: a first digital bandpass filter, configured to filter an upper sideband component of a received signal; The second digital bandpass filter is used to filter the lower sideband component of the received signal.

22. The system according to claim 19, characterized in that The system also includes: an optical splitter, the number of the coherent receivers is 2, the optical splitter is used to receive an optical signal from an optical transmission link, and divide the received optical signal into two optical signals, which are respectively input into the two coherent receivers, one of the two coherent receivers is used to perform upper sideband component filtering, and the other coherent receiver is used to perform lower sideband component filtering.

23. The system according to claim 22, characterized in that Each of the coherent receivers comprises: Local oscillator laser, used to generate coherent light; A polarization beam splitter, used to split an optical signal transmitted by an optical transmission link into a first polarized light and a second polarized light perpendicular to each other, and to split the coherent light into a third polarized light and a fourth polarized light perpendicular to each other; two 90° mixers, one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light; A photodetector, used for converting the optical signals output by the two 90° mixers into analog currents; A low-pass filter, used for filtering the analog current to obtain an electrical signal corresponding to a sideband component; The analog-to-digital converter is used to convert the electrical signal of the corresponding sideband component into a digital signal.

24. The system according to claim 22 or 23, characterized in that The system further comprises: a power measuring device, which is used for receiving an optical signal from an optical transmission link and measuring the power of a target signal in the optical signal.

25. The system according to any one of claims 20 or 23, characterized in that: The local oscillator laser has multiple adjustable center frequencies.

26. A computer device, characterized in that: The computer device comprises a processor and a memory, The memory stores computer instructions; the processor executes the computer instructions stored in the memory, so that the computer device executes the signal processing method according to any one of claims 1 to 9.

27. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions instruct a computer device to execute the signal processing method according to any one of claims 1 to 9.

28. A chip, characterized in that: The chip comprises a programmable logic circuit and / or program instructions, and when the chip is running, it is used to implement the signal processing method according to any one of claims 1 to 9.

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