Signal reconstruction system and method

Abstract

The present application relates to the field of optical communication technology, and discloses a signal reconstruction system and method. The system comprises: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter and a digital signal processing unit, wherein the optical mixer comprises a second optical coupler, a third optical coupler and a plurality of dispersion elements. The present application divides a complex-valued double-sideband signal to be measured into two paths through the first optical coupler, one path of the signal is subjected to square-law detection processing by the first photodetector to obtain a square-processed electrical signal, the other path of the signal is subjected to dispersion processing by the second optical coupler, the third optical coupler, a plurality of dispersion elements and the second photodetector to obtain a dispersion-processed electrical signal, the in-phase component of the information-bearing signal and the orthogonal component of the information-bearing signal are obtained by the digital signal processing unit to obtain a reconstructed signal, thereby effectively alleviating the frequency-selective power fading effect caused by the dispersion element and improving the quality and accuracy of the reconstructed signal.

Description

Technical Field

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

[0002] Driven by high-bandwidth Internet services, the traffic demand of data center interconnection and metropolitan area networks is growing exponentially. In order to meet this demand, the direct detection technology of complex-valued double-sideband signals has attracted much attention due to its potential advantages. This technology can achieve light field reconstruction like homodyne coherent detection while providing high spectral efficiency. However, the direct detection technology of complex-valued double-sideband signals also faces many challenges in the signal reconstruction process. For example, the introduction of some components will cause the received signal to suffer from severe frequency-selective power fading effects, thereby reducing the transmission performance of the system. Summary of the invention

[0003] The main purpose of the present application is to provide a signal reconstruction system and method, aiming to solve the technical problem that the signal in the existing signal reconstruction system suffers from severe frequency selective power fading effect, resulting in reduced transmission performance.

[0004] To achieve the above-mentioned object, the present application provides a signal reconstruction system, the signal reconstruction system comprising: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter and a digital signal processing unit, the optical mixer comprising a second optical coupler, a third optical coupler and a plurality of dispersion elements;

[0005] The first optical coupler is used to divide the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal;

[0006] The first photodetector is used to perform square-law detection on the first complex-valued double-sideband signal to obtain a squared electrical signal;

[0007] The optical mixer is used to process the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and the plurality of dispersion elements to obtain a dispersion-processed optical signal;

[0008] The second photodetector is used to convert the dispersion-processed optical signal into a dispersion-processed electrical signal;

[0009] The first analog-to-digital converter is used to perform sampling and quantization processing on the squared electrical signal to obtain a first digital signal;

[0010] The second analog-to-digital converter is used to perform sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal;

[0011] The digital signal processing unit is used to obtain an information-bearing signal in-phase component from the first digital signal and to obtain an information-bearing signal orthogonal component from the second digital signal;

[0012] The digital signal processing unit is further used to obtain a reconstructed signal according to the in-phase component of the information-bearing signal and the orthogonal component of the information-bearing signal.

[0013] In one embodiment, the optical mixer is further configured to receive the second complex-valued double-sideband signal through the second optical coupler, and divide the second complex-valued double-sideband signal into multiple signals;

[0014] The optical mixer is further used to process the multi-path signals in parallel through the multiple dispersion elements to generate signal components with different dispersion characteristics;

[0015] The optical mixer is further used to combine the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information.

[0016] In one embodiment, the digital signal processing unit is used to perform signal reconstruction on the first digital signal based on a signal reconstruction algorithm to obtain an in-phase component of the information bearing signal;

[0017] The digital signal processing unit is further used to reconstruct the second digital signal based on the time domain impulse responses of the multiple dispersion elements to obtain the orthogonal components of the information-bearing signal.

[0018] In one embodiment, the signal reconstruction system further includes a transmitter and an additive white Gaussian noise channel;

[0019] The transmitter is used to perform pulse shaping on the complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulate the shaped complex-valued double-sideband signal based on a preset guard band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal;

[0020] The additive white Gaussian noise channel is used to introduce additive white Gaussian noise into the modulated complex-valued double-sideband signal to obtain the complex-valued double-sideband signal to be measured.

[0021] In one embodiment, the digital signal processing unit is further used to eliminate interference in the reconstructed signal through a deep learning model or an iterative algorithm to obtain a reconstructed signal after elimination;

[0022] The digital signal processing unit is further used to obtain an optimized reconstructed signal by performing matched filtering on the eliminated reconstructed signal.

[0023] Furthermore, to achieve the above-mentioned purpose, the present application also provides a signal reconstruction method, which is applied to a signal reconstruction system, wherein the system comprises: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter and a digital signal processing unit, wherein the optical mixer comprises a second optical coupler, a third optical coupler and a plurality of dispersion elements; the method comprises:

[0024] The first optical coupler divides the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal;

[0025] The first photodetector performs square-law detection on the first complex-valued double-sideband signal to obtain a squared electrical signal;

[0026] The optical mixer processes the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and the plurality of dispersion elements to obtain a dispersion-processed optical signal;

[0027] The second photodetector converts the dispersion-processed optical signal into a dispersion-processed electrical signal;

[0028] The first analog-to-digital converter performs sampling and quantization processing on the squared electrical signal to obtain a first digital signal;

[0029] The second analog-to-digital converter performs sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal;

[0030] The digital signal processing unit obtains an information-bearing signal in-phase component from the first digital signal, and obtains an information-bearing signal orthogonal component from the second digital signal;

[0031] The digital signal processing unit obtains a reconstructed signal according to the in-phase component of the information bearing signal and the quadrature component of the information bearing signal.

[0032] In one embodiment, the optical mixer processes the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler, and the plurality of dispersion elements to obtain a dispersion-processed optical signal, comprising:

[0033] The optical mixer receives the second complex-valued double-sideband signal through the second optical coupler, and divides the second complex-valued double-sideband signal into multiple signals;

[0034] The optical mixer processes the multi-path signals in parallel through the multiple dispersion elements to generate signal components with different dispersion characteristics;

[0035] The optical mixer combines the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information.

[0036] In one embodiment, the step of the digital signal processing unit obtaining an in-phase component of an information-bearing signal from the first digital signal and obtaining an orthogonal component of an information-bearing signal from the second digital signal comprises:

[0037] The digital signal processing unit reconstructs the first digital signal based on a signal reconstruction algorithm to obtain an in-phase component of an information-bearing signal;

[0038] The digital signal processing unit reconstructs the second digital signal based on the time domain impulse responses of the multiple dispersion elements to obtain orthogonal components of information-bearing signals.

[0039] In one embodiment, the signal reconstruction system further includes a transmitter and an additive white Gaussian noise channel;

[0040] Before the step of dividing the complex-valued double-sideband signal to be measured by the first optical coupler into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal, the method further includes:

[0041] The transmitter performs pulse shaping on the complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulates the shaped complex-valued double-sideband signal based on a preset guard band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal;

[0042] The additive white Gaussian noise channel introduces additive white Gaussian noise into the modulated complex-valued double-sideband signal to obtain the complex-valued double-sideband signal to be measured.

[0043] In one embodiment, after the step of obtaining the reconstructed signal according to the in-phase component of the information bearing signal and the orthogonal component of the information bearing signal, the digital signal processing unit further comprises:

[0044] The digital signal processing unit eliminates interference in the reconstructed signal through a deep learning model or an iterative algorithm to obtain a reconstructed signal after elimination;

[0045] The digital signal processing unit obtains an optimized reconstructed signal by performing matched filtering on the eliminated reconstructed signal.

[0046] In addition, to achieve the above objectives, the present application also proposes a signal reconstruction device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the signal reconstruction method described above.

[0047] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the signal reconstruction method described above are implemented.

[0048] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the signal reconstruction method described above are implemented.

[0049] The technical solution proposed in the present application discloses a signal reconstruction system and method, the system includes: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter and a digital signal processing unit, the optical mixer includes a second optical coupler, a third optical coupler and a plurality of dispersion elements; the complex-valued double-sideband signal to be measured is divided into two paths by the first optical coupler, one signal is subjected to square-law detection processing by the first photodetector to obtain a square-processed electrical signal, the other signal is subjected to the second optical coupler, the third optical coupler, a plurality of dispersion elements and the second photodetector to obtain a dispersion-processed electrical signal, the information-bearing signal in-phase component and the information-bearing signal orthogonal component are obtained by the digital signal processing unit to obtain a reconstructed signal, the frequency-selective power fading effect caused by the dispersion elements is effectively alleviated, and the quality and accuracy of the reconstructed signal are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a structural block diagram of the first embodiment of the signal reconstruction system of the present application;

[0051] Figure 2 This is a schematic diagram of the signal reconstruction system components of this application;

[0052] Figure 3 It is a schematic diagram of the amplitude-frequency response curve of the orthogonal components of the time domain impulse response;

[0053] Figure 4 It is a schematic diagram of the pre-processing of the complex-valued double-sideband signal to be measured;

[0054] Figure 5 It is a schematic diagram for comparing bit error performance under different optical signal-to-noise ratio conditions;

[0055] Figure 6 This is a flow chart of the first embodiment of the signal reconstruction method of the present application;

[0056] Figure 7 This is a flow chart of the second embodiment of the signal reconstruction method of the present application;

[0057] Figure 8Schematic diagram of the device structure of the hardware operating environment involved in the signal reconstruction method in the embodiment of the present application.

[0058] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0059] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0060] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0061] The direct detection technology of complex-valued double-sideband signals also faces many challenges in the signal reconstruction process. For example, the introduction of some components will cause the received signal to suffer from severe frequency-selective power fading effects, thereby reducing the transmission performance of the system.

[0062] Therefore, in order to overcome the above-mentioned defects, the present application provides a solution, which divides the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal through a first optical coupler, obtains a square-processed electrical signal through the square-law detection processing of the first photodetector, obtains a dispersion-processed electrical signal through the other signal through the second optical coupler, the third optical coupler, multiple dispersion elements and the second photodetector, obtains the information-bearing signal in-phase component and the information-bearing signal orthogonal component through the digital signal processing unit, and then obtains the reconstructed signal, thereby effectively alleviating the frequency selective power fading effect caused by the dispersion element and improving the quality and accuracy of the reconstructed signal.

[0063] Based on this, the embodiment of the present application provides a signal reconstruction system, referring to Figure 1 , Figure 1 This is a structural block diagram of the first embodiment of the signal reconstruction system of the present application. The signal reconstruction system includes: a first optical coupler 10, a first photodetector 20, an optical mixer 30, a second photodetector 40, a first analog-to-digital converter 50, a second analog-to-digital converter 60 and a digital signal processing unit 70, wherein the optical mixer 30 includes a second optical coupler, a third optical coupler and a plurality of dispersion elements.

[0064] The first optical coupler 10 is used to divide the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal.

[0065] It should be understood that signal reconstruction plays a vital role in many fields. From the perspective of information recovery, signals are often affected by various noises, interferences or hardware limitations during transmission, storage or processing, resulting in signal quality degradation or distortion. Signal reconstruction can accurately extract and restore the original signal (i.e., reconstructed signal) from the damaged or distorted signal by using known signal characteristics or prior information, thereby ensuring the integrity and accuracy of the information.

[0066] It should be noted that the optical coupler is used to couple an optical signal from one path to another, and is usually used for the distribution or merging of optical signals; a complex-valued double-sideband signal is a signal form including a carrier and an information-bearing signal, wherein the information-bearing signal is a complex signal including an in-phase component and an orthogonal component, and the in-phase component and the orthogonal component are usually used to represent the real part and the imaginary part of a complex signal.

[0067] In addition, it should be noted that the complex-valued double-sideband signal to be measured may be obtained directly from a dedicated signal source or other source, or may be directly output from a transmitter, or may be obtained after a series of preprocessing or different processing steps. This embodiment does not limit this. The transmitter is a device responsible for converting the signal into a format suitable for transmission and sending it out. The complex-valued double-sideband signal to be measured may be a signal directly output by the transmitter. These signals are sent to the channel for transmission after being modulated, encoded, and other processing.

[0068] It should be understood that the complex-valued double-sideband signal to be measured carries information on both sidebands of the optical carrier. Complex-valued means that these signals have not only amplitude (intensity) changes, but also phase changes. Double-sideband means that the information is modulated on both sides of the carrier frequency to form two symmetrical sidebands. The main function of the first optical coupler is to divide the input complex-valued double-sideband signal to be measured into two independent signal paths. The signals on these two paths are the first complex-valued double-sideband signal and the second complex-valued double-sideband signal.

[0069] It should be noted that the first optical coupler and the second optical coupler in the signal reconstruction system of the present application may also be combined into one optical coupler as a variation of the technical solution of the present application.

[0070] In addition, it should be noted that the signal reconstruction system of the present application has excellent versatility and practicality, and can be widely used in scenarios including but not limited to obstacle detection of driverless cars, celestial observation of space telescopes, remote education and medical consultation in satellite communication systems, etc.

[0071] The first photodetector 20 is used to perform square-law detection on the first complex-valued double-sideband signal to obtain a squared electrical signal.

[0072] It should be noted that a photodetector is a device that converts an optical signal into an analog electrical signal; square-law detection is a special signal processing technology based on the nonlinear response characteristics of the photodetector. The photodetector in this application can be an AC-coupled photodetector that has the function of isolating DC current, or a DC-coupled photodetector that performs DC isolation in the digital signal processing process.

[0073] It can be understood that when the photodetector receives a light signal, its output current is proportional to the incident light intensity (when the light intensity is weak, this relationship is approximately true). Therefore, when the first photodetector receives the first complex-valued double-sideband signal, it outputs a square-processed electrical signal proportional to the square of the first complex-valued double-sideband signal based on square-law detection.

[0074] The optical mixer 30 is used to process the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and the multiple dispersion elements to obtain a dispersion-processed optical signal.

[0075] It should be noted that an optical mixer is used to mix two or more optical signals to generate a new optical signal, and is often used in processes such as frequency conversion, modulation or demodulation; a dispersion element is an element used to introduce phase delay differences between different frequency components in an optical signal, and is often used in applications such as spectral analysis and dispersion compensation.

[0076] The dispersion elements (at least two) in the present application may include single-mode optical fiber, dispersion compensation module, dispersion compensation optical fiber, silicon photonic integrated on-chip dispersion compensation device, etc., and because the dispersion elements have a full-pass amplitude response, the signal reconstruction system proposed in the present application is insensitive to laser wavelength drift.

[0077] The second photodetector 40 is used to convert the dispersion-processed optical signal into a dispersion-processed electrical signal.

[0078] The first analog-to-digital converter 50 is used to perform sampling and quantization processing on the squared electrical signal to obtain a first digital signal.

[0079] The second analog-to-digital converter 60 is used to perform sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal.

[0080] It should be noted that the signal reconstruction system of the present application further includes an analog-to-digital converter, which may include a first analog-to-digital converter and a second analog-to-digital converter. An analog-to-digital converter (ADC) is an electronic device that converts an analog signal into a digital signal and is an interface between an analog signal and a digital signal processing system.

[0081] In this step, the collected squared electrical signal and dispersion processed electrical signal need to be sampled and quantized based on the first analog-to-digital converter and the second analog-to-digital converter to obtain the first digital signal and the second digital signal. Sampling is the process of converting a continuous-time signal into a discrete-time signal, and quantization is the process of converting the sampled signal amplitude into a digital representation of finite precision.

[0082] The digital signal processing unit 70 is used to obtain an in-phase component of an information-bearing signal from the first digital signal, and to obtain a quadrature component of an information-bearing signal from the second digital signal.

[0083] It should be noted that a digital signal processing unit (DSP) refers to a hardware or software component specifically used to perform digital signal processing tasks, such as filtering, transformation, detection, etc. The core task of the digital signal processing unit is to process the input digital signals based on preset formulas and algorithms, and execute various algorithms based on these signals to generate the required output signals.

[0084] It is understood that the digital signal processing unit obtains components from analog signals of two different sources, obtains the information-bearing signal in-phase component from the first digital signal, and obtains the information-bearing signal orthogonal component from the second digital signal.

[0085] The digital signal processing unit 70 is further configured to obtain a reconstructed signal according to the in-phase component of the information bearing signal and the quadrature component of the information bearing signal.

[0086] It is understandable that in order to obtain the reconstructed signal, the digital signal processing unit needs to implement a series of complex algorithms, which may include digital filtering, Fourier transform, inverse Fourier transform, phase recovery, amplitude adjustment and other steps, aiming to accurately obtain and restore the original signal from the in-phase component and the orthogonal component of the information-bearing signal.

[0087] The digital signal processing unit 70 is further used to eliminate interference in the reconstructed signal through a deep learning model or an iterative algorithm to obtain a reconstructed signal after elimination.

[0088] It should be understood that the digital signal processing unit uses a deep learning model and / or an iterative algorithm to eliminate interference in the reconstructed signal, such as using a neural network in a deep learning model to identify and remove noise and interference in the reconstructed signal by learning features in a large amount of data. The iterative algorithm is a method of gradually approaching the real signal. Through multiple iterations, the algorithm can gradually approach and remove interference in the reconstructed signal until a preset error threshold or a preset number of iterations is reached. As the number of iterations increases, the purity of the signal can be continuously improved.

[0089] The digital signal processing unit 70 is further configured to obtain an optimized reconstructed signal by performing matched filtering on the eliminated reconstructed signal.

[0090] When performing matched filtering on the reconstructed signal after eliminating interference, the digital signal processing unit applies a filter that matches the signal characteristics. A matched filter is a special type of filter that is designed based on prior knowledge of the signal (such as the waveform and frequency of the signal). It can maximize the acquisition of useful information in the signal while suppressing noise and interference. Through matched filtering, the digital signal processing unit can further optimize the quality of the reconstructed signal, for example, improving the signal-to-noise ratio of the reconstructed signal and improving the spectral characteristics of the reconstructed signal.

[0091] In this embodiment, the complex-valued double-sideband signal to be measured is divided into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal through a first optical coupler, and one signal is subjected to square-law detection processing by a first photodetector to obtain a square-processed electrical signal, and another signal is subjected to dispersion processing by a second optical coupler, a third optical coupler, a plurality of dispersion elements, and a second photodetector to obtain a dispersion-processed electrical signal, and the in-phase component of the information-bearing signal and the orthogonal component of the information-bearing signal are obtained by a digital signal processing unit, and then a reconstructed signal is obtained, thereby effectively alleviating the frequency-selective power fading effect caused by the dispersion element, and improving the quality and accuracy of the reconstructed signal. In addition, the digital signal processing unit eliminates interference and performs matched filtering processing on the reconstructed signal through a deep learning model and / or an iterative algorithm to optimize the reconstructed signal, further improving the signal quality and reliability.

[0092] As an implementation manner, the optical mixer 30 is further configured to receive the second complex-valued double-sideband signal through the second optical coupler, and divide the second complex-valued double-sideband signal into multiple signals.

[0093] It should be understood that after receiving the second complex-valued double-sideband signal, the optical mixer will split it into multiple signals. By splitting the signal, the optical mixer can distribute the originally complex processing task to multiple dispersive element parallel channels.

[0094] The optical mixer 30 is further configured to process the multi-path signals in parallel through the multiple dispersion elements to generate signal components with different dispersion characteristics.

[0095] An optical mixer processes multi-path signals in parallel through multiple dispersion elements, that is, generates signal components with different dispersion characteristics. These signal components present different distributions on the spectrum, thereby carrying different information about the original signal.

[0096] The optical mixer 30 is further configured to combine the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information.

[0097] The optical mixer combines signal components with different dispersion characteristics through a third optical coupler. The purpose of this step is to reintegrate the information scattered on multiple channels to form a dispersion-processed optical signal containing orthogonal component information. This optical signal not only retains most of the information of the original signal, but also introduces new characteristics through dispersion processing, such as spectrum expansion and phase modulation.

[0098] For ease of understanding, refer to Figure 2 and Figure 3 This is for illustration only, but is not intended to limit the signal reconstruction system of this application. Figure 2 This is a schematic diagram of the signal reconstruction system components of the present application, including: a first optical coupler and a parallel information-carrying signal in-phase component detection branch and an information-carrying signal orthogonal component detection branch, wherein the information-carrying signal in-phase component detection branch includes a first photodetector and a first analog-to-digital converter connected in sequence; the information-carrying signal orthogonal component detection branch includes an optical mixer, a second photodetector, and a second analog-to-digital converter connected in sequence. The time domain impulse response of each dispersion element is expressed as , … The complex-valued double-sideband signal to be measured ( is the carrier wave, The information-carrying signal is divided into two identical parts by the first optical coupler:

[0099] The photocurrent output by the first photodetector in the in-phase component detection branch of the information-carrying signal , the in-phase component of the information-carrying signal is obtained by reconstruction ; In the other branch, the optical signal output by the optical mixer is The second photodetector outputs a photocurrent

[0100] , after reconstruction, the information-carrying signal orthogonal components are obtained

[0101] ,in: is the carrier wave, For information carrying signals, and for The in-phase and quadrature components of is the time domain impulse response of the optical mixer, which is composed of the time domain impulse responses of multiple dispersive elements. and for The in-phase and quadrature components of is a linear convolution, To take the real part operation, yes The reciprocal of in the frequency domain. Therefore, the reconstructed signal is It can be seen that the reconstructed original signal not only has the in-phase component of the information-carrying signal and the orthogonal component of the information-carrying signal, but also the information-carrying signal The second-order term of , namely Signal-Signal Beat Interference (SSBI), can be eliminated using deep learning models and / or iterative algorithms.

[0102] Taking the use of three dispersion elements as an example, the dispersion elements are implemented as single-mode optical fibers, and the dispersion coefficient of the optical fiber is 16.8 ps / (nm·km). Figure 3 is the orthogonal component of the time domain impulse response (i.e. ), the "Mixer (7+23+60 km)" in the figure indicates that three single-mode optical fibers with lengths of 7 km, 23 km and 60 km are used to construct a multi-channel dispersion parallel mixer; the "7 km" in the figure indicates that a single-mode optical fiber with a length of 7 km is used to construct the mixer; the "60 km" in the figure indicates that a single-mode optical fiber with a length of 60 km is used to construct the mixer. It is worth noting that the single-mode optical fiber can be replaced by other dispersion elements with equal dispersion values, such as dispersion compensation modules, dispersion compensation optical fibers, dispersion compensation devices on silicon photonic integrated chips, etc. Figure 3 It can be seen that the mixer using multiple dispersive elements in parallel is better than the mixer composed of a single dispersive element. The frequency response curve of The error term in In the specific implementation process, it is necessary to select the appropriate number of dispersion elements and dispersion value. The goal is to make Theoretically, the more dispersion elements are used, the more The flatter the amplitude-frequency response curve is, the system performance and implementation cost need to be balanced. In actual operation, 2 to 3 dispersion elements are generally used. In particular, do not let the singular point ( Figure 3 The peak that appears in the chromatic aberration is located within the frequency band of the information-carrying signal. Theoretically, the smaller the dispersion value, the higher the frequency of the first singular point. However, near the zero frequency, The larger the amplitude of is, the greater the enhancement of the error term is. It should be noted that no matter how the number of dispersion elements and the dispersion value are selected, the singular point at zero frequency cannot be avoided, so a guard band needs to be added at zero frequency.

[0103] In this embodiment, the optical mixer receives the second complex-valued double-sideband signal through the second optical coupler, and divides the second complex-valued double-sideband signal into multiple signals. The optical mixer processes the multiple signals in parallel through multiple dispersion elements to generate signal components with different dispersion characteristics. The optical mixer combines the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information, thereby increasing signal diversity and enhancing the signal's anti-noise and anti-interference capabilities.

[0104] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above embodiment 1 can be referred to the above introduction, and will not be described in detail later. Figure 1 The illustrated embodiment provides a second embodiment of the signal reconstruction system of the present application.

[0105] In this embodiment, the digital signal processing unit 70 is used to reconstruct the first digital signal based on a signal reconstruction algorithm to obtain an in-phase component of the information bearing signal;

[0106] The digital signal processing unit 70 is further configured to reconstruct the second digital signal based on the time domain impulse responses of the plurality of dispersion elements to obtain orthogonal components of information-bearing signals.

[0107] It can be understood that the digital signal processing unit further processes the first digital signal based on the signal reconstruction algorithm to reconstruct the in-phase component of the information-carrying signal. At the same time, the second digital signal is reconstructed based on the time domain pulse response of multiple dispersion elements. Among them, the time domain pulse response describes the response mode of the dispersion element to the input signal. The signal can be accurately reconstructed using this information, and the reconstruction result is the orthogonal component of the information-carrying signal. Through the digital signal processing unit, the in-phase component and the orthogonal component of the original information-carrying optical signal can be obtained and reconstructed from the differently processed electrical signals. These two components together constitute the complete information of the signal.

[0108] In this embodiment, the digital signal processing unit reconstructs the first digital signal based on a signal reconstruction algorithm to obtain the in-phase component of the information-bearing signal, and reconstructs the second digital signal based on the time domain pulse response of multiple dispersion elements, thereby accurately obtaining the orthogonal component of the information-bearing signal and improving the integrity of the signal.

[0109] As an implementation mode, the signal reconstruction system further includes a transmitter and an additive white Gaussian noise channel;

[0110] The transmitter is used to perform pulse shaping on a complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and to modulate the shaped complex-valued double-sideband signal based on a preset protection band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal.

[0111] The additive white Gaussian noise channel is used to introduce additive white Gaussian noise into the modulated complex-valued double-sideband signal to obtain the complex-valued double-sideband signal to be measured.

[0112] It should be understood that the transmitter first performs pulse shaping on the complex-valued double-sideband signal based on the root raised cosine filter algorithm. The root raised cosine filter algorithm is a common algorithm for pulse shaping, which can control the spectral shape of the signal by adjusting the parameters of the filter, thereby optimizing the transmission performance of the signal. After pulse shaping, the transmitter modulates the shaped complex-valued double-sideband signal based on the preset guard band and the carrier signal power ratio. The preset guard band is a frequency interval set to prevent interference between signals, and the carrier signal power ratio determines the power relationship between the signal and the carrier. The modulated complex-valued double-sideband signal will be sent to the channel for transmission.

[0113] It should be noted that the additive white Gaussian noise channel is a simulated environment in the signal transmission process, which is used to test the transmission performance of the signal in a real environment; additive white Gaussian noise is a type of noise with uniform distribution in both time and frequency, which simulates various random interferences existing in the real environment.

[0114] In the modulated complex-valued double-sideband signal, the additive white Gaussian noise channel will introduce a certain amount of additive white Gaussian noise. After being processed by the additive white Gaussian noise channel, the modulated complex-valued double-sideband signal will become the complex-valued double-sideband signal to be tested. This signal contains the original information and the noise introduced by the channel, and can be used for subsequent signal processing, demodulation, and testing.

[0115] For ease of understanding, refer to Figure 4 and Figure 5 This is for illustration only, but is not intended to limit the signal reconstruction method of the present application. Figure 4The schematic diagram of the pre-processing of the complex-valued double-sideband signal to be tested is shown in FIG. The transmitter is set to output a 28 GBuad pulse-shaped complex-valued double-sideband 16-ary quadrature amplitude modulation (16-QAM) signal, the roll-off coefficient of the root raised cosine filter algorithm is 0.01, and a 6 GHz guard band is inserted at the zero frequency of the complex-valued double-sideband signal, that is, -3 GHz to 3 GHz, and the carrier signal power ratio is set to 8 dB. The complex-valued double-sideband 16-QAM signal is introduced with additive white Gaussian noise to simulate the optical fiber channel.

[0116] At the receiving end, the signal is reconstructed using the steps described above, and interference is eliminated using an iterative algorithm. Finally, after matched filtering and bit error rate calculation, we get Figure 5 The bit error performance shown ( Figure 5 (Figure 2 is a schematic diagram for comparing bit error performance under different optical signal-to-noise ratio conditions). Figure 5 The error performance comparison diagram of the present invention and other solutions under different optical signal-to-noise ratio conditions in the embodiment is shown. The dispersion diversity detection method in the prior art of "7, 23, 60 km" described in the figure.

[0117] Compared with the solution of using a single dispersive element to build an optical mixer, the present application can obtain a lower bit error rate and significantly improve the system performance. Compared with the dispersion diversity detection method, the present application reduces the use of two photodetectors and two analog-to-digital converters at the receiving end, while reducing the system cost, and still can obtain slightly better system performance. By optimizing the number of dispersive elements used and the dispersion value, the present application can greatly alleviate the impact of the frequency selective power fading effect caused by the dispersive element on the complex-valued double-sideband signal to be measured, thereby significantly improving the system performance.

[0118] In this embodiment, the transmitter performs pulse shaping on the complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulates the shaped complex-valued double-sideband signal based on a preset protection band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal. An additive Gaussian white noise channel introduces additive Gaussian white noise into the modulated complex-valued double-sideband signal to obtain a complex-valued double-sideband signal to be measured, which not only enhances the anti-interference ability of the signal, but also improves the transmission quality and accuracy of the signal.

[0119] Reference Figure 6 The signal reconstruction system of the present application provides a signal reconstruction method. Figure 6This is a flow chart of the first embodiment of the signal reconstruction method of the present application. The signal reconstruction system includes: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter, and a digital signal processing unit. The optical mixer includes a second optical coupler, a third optical coupler, and a plurality of dispersion elements. The signal reconstruction method includes steps S10 to S80:

[0120] Step S10: the first optical coupler divides the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal.

[0121] It should be understood that signal reconstruction plays a vital role in many fields. From the perspective of information recovery, signals are often affected by various noises, interferences or hardware limitations during transmission, storage or processing, resulting in signal quality degradation or distortion. Signal reconstruction can accurately extract and restore the original signal (i.e., reconstructed signal) from the damaged or distorted signal by using known signal characteristics or prior information, thereby ensuring the integrity and accuracy of the information.

[0122] It should be noted that the optical coupler is used to couple an optical signal from one path to another, and is usually used for the distribution or merging of optical signals; a complex-valued double-sideband signal is a signal form including a carrier and an information-bearing signal, wherein the information-bearing signal is a complex signal including an in-phase component and an orthogonal component, and the in-phase component and the orthogonal component are usually used to represent the real part and the imaginary part of a complex signal.

[0123] In addition, it should be noted that the complex-valued double-sideband signal to be measured may be obtained directly from a dedicated signal source or other source, or may be directly output from a transmitter, or may be obtained after a series of preprocessing or different processing steps. This embodiment does not limit this. The transmitter is a device responsible for converting the signal into a format suitable for transmission and sending it out. The complex-valued double-sideband signal to be measured may be a signal directly output by the transmitter. These signals are sent to the channel for transmission after being modulated, encoded, and other processing.

[0124] It should be understood that the complex-valued double-sideband signal to be measured carries information on both sidebands of the optical carrier. Complex-valued means that these signals have not only amplitude (intensity) changes, but also phase changes. Double-sideband means that the information is modulated on both sides of the carrier frequency to form two symmetrical sidebands. The main function of the first optical coupler is to divide the input complex-valued double-sideband signal to be measured into two independent signal paths. The signals on these two paths are the first complex-valued double-sideband signal and the second complex-valued double-sideband signal.

[0125] It should be noted that the first optical coupler and the second optical coupler in the signal reconstruction system of the present application may also be combined into one optical coupler as a variation of the technical solution of the present application.

[0126] In addition, it should be noted that the signal reconstruction system of the present application has excellent versatility and practicality, and can be widely used in scenarios including but not limited to obstacle detection of driverless cars, celestial observation of space telescopes, remote education and medical consultation in satellite communication systems, etc.

[0127] Step S20: the first photodetector performs square-law detection on the first complex-valued double-sideband signal to obtain a squared electrical signal.

[0128] It should be noted that a photodetector is a device that converts an optical signal into an analog electrical signal; square-law detection is a special signal processing technology based on the nonlinear response characteristics of the photodetector. The photodetector in this application can be an AC-coupled photodetector that has the function of isolating DC current, or a DC-coupled photodetector that performs DC isolation in the digital signal processing process.

[0129] It can be understood that when the photodetector receives a light signal, its output current is proportional to the incident light intensity (when the light intensity is weak, this relationship is approximately true). Therefore, when the first photodetector receives the first complex-valued double-sideband signal, it outputs a square-processed electrical signal proportional to the square of the first complex-valued double-sideband signal based on square-law detection.

[0130] Step S30: The optical mixer processes the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler, and the plurality of dispersion elements to obtain a dispersion-processed optical signal.

[0131] It should be noted that an optical mixer is used to mix two or more optical signals to generate a new optical signal, and is often used in processes such as frequency conversion, modulation or demodulation; a dispersion element is an element used to introduce phase delay differences between different frequency components in an optical signal, and is often used in applications such as spectral analysis and dispersion compensation.

[0132] The dispersion elements (at least two) in the present application may include single-mode optical fiber, dispersion compensation module, dispersion compensation optical fiber, silicon photonic integrated on-chip dispersion compensation device, etc., and because the dispersion elements have a full-pass amplitude response, the signal reconstruction system proposed in the present application is insensitive to laser wavelength drift.

[0133] Step S40: the second photodetector converts the dispersion-processed optical signal into a dispersion-processed electrical signal.

[0134] Step S50: the first analog-to-digital converter performs sampling and quantization processing on the squared electrical signal to obtain a first digital signal.

[0135] Step S60: the second analog-to-digital converter performs sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal.

[0136] It should be noted that the signal reconstruction system of the present application further includes an analog-to-digital converter, which may include a first analog-to-digital converter and a second analog-to-digital converter. An analog-to-digital converter (ADC) is an electronic device that converts an analog signal into a digital signal and is an interface between an analog signal and a digital signal processing system.

[0137] In this step, the collected squared electrical signal and dispersion processed electrical signal need to be sampled and quantized based on the first analog-to-digital converter and the second analog-to-digital converter to obtain the first digital signal and the second digital signal. Sampling is the process of converting a continuous-time signal into a discrete-time signal, and quantization is the process of converting the sampled signal amplitude into a digital representation of finite precision.

[0138] Step S70: the digital signal processing unit obtains an in-phase component of an information-bearing signal from the first digital signal, and obtains a quadrature component of an information-bearing signal from the second digital signal.

[0139] It should be noted that a digital signal processing unit (DSP) refers to a hardware or software component specifically used to perform digital signal processing tasks, such as filtering, transformation, detection, etc. The core task of the digital signal processing unit is to process the input digital signals based on preset formulas and algorithms, and execute various algorithms based on these signals to generate the required output signals.

[0140] It is understood that the digital signal processing unit obtains components from analog signals of two different sources, obtains the information-bearing signal in-phase component from the first digital signal, and obtains the information-bearing signal orthogonal component from the second digital signal.

[0141] Step S80: the digital signal processing unit obtains a reconstructed signal according to the in-phase component of the information bearing signal and the quadrature component of the information bearing signal.

[0142] It is understandable that in order to obtain the reconstructed signal, the digital signal processing unit needs to implement a series of complex algorithms, which may include digital filtering, Fourier transform, inverse Fourier transform, phase recovery, amplitude adjustment and other steps, aiming to accurately obtain and restore the original signal from the in-phase component and the orthogonal component of the information-bearing signal.

[0143] In this embodiment, the above-mentioned step S80 may also include: the digital signal processing unit eliminates interference in the reconstructed signal through a deep learning model or an iterative algorithm to obtain a reconstructed signal after elimination; the digital signal processing unit obtains an optimized reconstructed signal by performing matched filtering on the reconstructed signal after elimination.

[0144] It should be understood that the digital signal processing unit uses a deep learning model and / or an iterative algorithm to eliminate interference in the reconstructed signal, such as using a neural network in a deep learning model to identify and remove noise and interference in the reconstructed signal by learning features in a large amount of data. The iterative algorithm is a method of gradually approaching the real signal. Through multiple iterations, the algorithm can gradually approach and remove interference in the reconstructed signal until a preset error threshold or a preset number of iterations is reached. As the number of iterations increases, the purity of the signal can be continuously improved.

[0145] When performing matched filtering on the reconstructed signal after eliminating interference, the digital signal processing unit applies a filter that matches the signal characteristics. A matched filter is a special type of filter that is designed based on prior knowledge of the signal (such as the waveform and frequency of the signal). It can maximize the acquisition of useful information in the signal while suppressing noise and interference. Through matched filtering, the digital signal processing unit can further optimize the quality of the reconstructed signal, for example, improving the signal-to-noise ratio of the reconstructed signal and improving the spectral characteristics of the reconstructed signal.

[0146] In this embodiment, the complex-valued double-sideband signal to be measured is divided into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal through a first optical coupler, and one signal is subjected to square-law detection processing by a first photodetector to obtain a square-processed electrical signal, and another signal is subjected to dispersion processing by a second optical coupler, a third optical coupler, a plurality of dispersion elements, and a second photodetector to obtain a dispersion-processed electrical signal, and the in-phase component of the information-bearing signal and the orthogonal component of the information-bearing signal are obtained by a digital signal processing unit, and then a reconstructed signal is obtained, thereby effectively alleviating the frequency-selective power fading effect caused by the dispersion element, and improving the quality and accuracy of the reconstructed signal. In addition, the digital signal processing unit eliminates interference and performs matched filtering processing on the reconstructed signal through a deep learning model and / or an iterative algorithm to optimize the reconstructed signal, further improving the signal quality and reliability.

[0147] As an implementation manner, the above-mentioned step S30 in this embodiment may include: the optical mixer receives the second complex-valued double-sideband signal through the second optical coupler, and divides the second complex-valued double-sideband signal into multiple signals; the optical mixer processes the multiple signals in parallel through the multiple dispersion elements to generate signal components with different dispersion characteristics; the optical mixer combines the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information.

[0148] It should be understood that after receiving the second complex-valued double-sideband signal, the optical mixer will split it into multiple signals. By splitting the signal, the optical mixer can distribute the originally complex processing task to multiple dispersive element parallel channels.

[0149] An optical mixer processes multi-path signals in parallel through multiple dispersion elements, that is, generates signal components with different dispersion characteristics. These signal components present different distributions on the spectrum, thereby carrying different information about the original signal.

[0150] The optical mixer combines signal components with different dispersion characteristics through a third optical coupler. The purpose of this step is to reintegrate the information scattered on multiple channels to form a dispersion-processed optical signal containing orthogonal component information. This optical signal not only retains most of the information of the original signal, but also introduces new characteristics through dispersion processing, such as spectrum expansion and phase modulation.

[0151] For ease of understanding, refer to Figure 2 and Figure 3 This is for illustration only, but is not intended to limit the signal reconstruction system of this application. Figure 2 This is a schematic diagram of the signal reconstruction system components of the present application, including: a first optical coupler and a parallel information-carrying signal in-phase component detection branch and an information-carrying signal orthogonal component detection branch, wherein the information-carrying signal in-phase component detection branch includes a first photodetector and a first analog-to-digital converter connected in sequence; the information-carrying signal orthogonal component detection branch includes an optical mixer, a second photodetector, and a second analog-to-digital converter connected in sequence. The time domain impulse response of each dispersion element is expressed as , … The complex-valued double-sideband signal to be measured ( is the carrier wave, The information-carrying signal is divided into two identical parts by the first optical coupler:

[0152] The photocurrent output by the first photodetector in the in-phase component detection branch of the information-carrying signal , the in-phase component of the information-carrying signal is obtained by reconstruction ; In the other branch, the optical signal output by the optical mixer is The second photodetector outputs a photocurrent

[0153] , after reconstruction, the information-carrying signal orthogonal components are obtained

[0154] ,in: is the carrier wave, For information carrying signals, and for The in-phase and quadrature components of is the time domain impulse response of the optical mixer, which is composed of the time domain impulse responses of multiple dispersive elements. and for The in-phase and quadrature components of is a linear convolution, To take the real part operation, yes The reciprocal of in the frequency domain. Therefore, the reconstructed signal is It can be seen that the reconstructed original signal not only has the in-phase component of the information-carrying signal and the orthogonal component of the information-carrying signal, but also the information-carrying signal The second-order term of , namely Signal-Signal Beat Interference (SSBI), can be eliminated using deep learning models and / or iterative algorithms.

[0155] Taking the use of three dispersion elements as an example, the dispersion elements are implemented as single-mode optical fibers, and the dispersion coefficient of the optical fiber is 16.8 ps / (nm·km). Figure 3 is the orthogonal component of the time domain impulse response (i.e. ), the "Mixer (7+23+60 km)" in the figure indicates that three single-mode optical fibers with lengths of 7 km, 23 km and 60 km are used to construct a multi-channel dispersion parallel mixer; the "7 km" in the figure indicates that a single-mode optical fiber with a length of 7 km is used to construct the mixer; the "60 km" in the figure indicates that a single-mode optical fiber with a length of 60 km is used to construct the mixer. It is worth noting that the single-mode optical fiber can be replaced by other dispersion elements with equal dispersion values, such as dispersion compensation modules, dispersion compensation optical fibers, dispersion compensation devices on silicon photonic integrated chips, etc. Figure 3 It can be seen that the mixer using multiple dispersive elements in parallel is better than the mixer composed of a single dispersive element. The frequency response curve of The error term in In the specific implementation process, it is necessary to select the appropriate number of dispersion elements and dispersion value. The goal is to make Theoretically, the more dispersion elements are used, the more The flatter the amplitude-frequency response curve is, the system performance and implementation cost need to be balanced. In actual operation, 2 to 3 dispersion elements are generally used. In particular, do not let the singular point ( Figure 3 The peak that appears in the chromatic aberration is located within the frequency band of the information-carrying signal. Theoretically, the smaller the dispersion value, the higher the frequency of the first singular point. However, near the zero frequency, The larger the amplitude of is, the greater the enhancement of the error term is. It should be noted that no matter how the number of dispersion elements and the dispersion value are selected, the singular point at zero frequency cannot be avoided, so a guard band needs to be added at zero frequency.

[0156] In this embodiment, the optical mixer receives the second complex-valued double-sideband signal through the second optical coupler, and divides the second complex-valued double-sideband signal into multiple signals. The optical mixer processes the multiple signals in parallel through multiple dispersion elements to generate signal components with different dispersion characteristics. The optical mixer combines the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information, thereby increasing signal diversity and enhancing the signal's anti-noise and anti-interference capabilities.

[0157] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above-mentioned embodiment 1 can be referred to the above introduction, and will not be repeated in the following. Figure 7 , the step S70 may include steps S701-S702:

[0158] Step S701: the digital signal processing unit reconstructs the first digital signal based on a signal reconstruction algorithm to obtain an in-phase component of an information bearing signal.

[0159] Step S702: The digital signal processing unit reconstructs the second digital signal based on the time domain impulse responses of the multiple dispersion elements to obtain orthogonal components of information bearing signals.

[0160] It can be understood that the digital signal processing unit further processes the first digital signal based on the signal reconstruction algorithm to reconstruct the in-phase component of the information-carrying signal. At the same time, the second digital signal is reconstructed based on the time domain pulse response of multiple dispersion elements. Among them, the time domain pulse response describes the response mode of the dispersion element to the input signal. The signal can be accurately reconstructed using this information, and the reconstruction result is the orthogonal component of the information-carrying signal. Through the digital signal processing unit, the in-phase component and the orthogonal component of the original information-carrying optical signal can be obtained and reconstructed from the differently processed electrical signals. These two components together constitute the complete information of the signal.

[0161] In this embodiment, the digital signal processing unit reconstructs the first digital signal based on a signal reconstruction algorithm to obtain the in-phase component of the information-bearing signal, and reconstructs the second digital signal based on the time domain pulse response of multiple dispersion elements, thereby accurately obtaining the orthogonal component of the information-bearing signal and improving the integrity of the signal.

[0162] As an implementation manner, the signal reconstruction system further includes a transmitter and an additive white Gaussian noise channel; before the step S10, steps S01-S02 may also be included:

[0163] Step S01: The transmitter performs pulse shaping on a complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulates the shaped complex-valued double-sideband signal based on a preset protection band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal.

[0164] It should be understood that the transmitter first performs pulse shaping on the complex-valued double-sideband signal based on the root raised cosine filter algorithm. The root raised cosine filter algorithm is a common algorithm for pulse shaping, which can control the spectral shape of the signal by adjusting the parameters of the filter, thereby optimizing the transmission performance of the signal. After pulse shaping, the transmitter modulates the shaped complex-valued double-sideband signal based on the preset guard band and the carrier signal power ratio. The preset guard band is a frequency interval set to prevent interference between signals, and the carrier signal power ratio determines the power relationship between the signal and the carrier. The modulated complex-valued double-sideband signal will be sent to the channel for transmission.

[0165] Step S02: the additive white Gaussian noise channel introduces additive white Gaussian noise into the modulated complex-valued double-sideband signal to obtain a complex-valued double-sideband signal to be measured.

[0166] It should be noted that the additive white Gaussian noise channel is a simulated environment in the signal transmission process, which is used to test the transmission performance of the signal in a real environment; additive white Gaussian noise is a type of noise with uniform distribution in both time and frequency, which simulates various random interferences existing in the real environment.

[0167] In the modulated complex-valued double-sideband signal, the additive white Gaussian noise channel will introduce a certain amount of additive white Gaussian noise. After being processed by the additive white Gaussian noise channel, the modulated complex-valued double-sideband signal will become the complex-valued double-sideband signal to be tested. This signal contains the original information and the noise introduced by the channel, and can be used for subsequent signal processing, demodulation, and testing.

[0168] For ease of understanding, refer to Figure 4 and Figure 5 This is for illustration only, but is not intended to limit the signal reconstruction method of the present application. Figure 4 The schematic diagram of the pre-processing of the complex-valued double-sideband signal to be tested is shown in FIG. The transmitter is set to output a 28 GBuad pulse-shaped complex-valued double-sideband 16-ary quadrature amplitude modulation (16-QAM) signal, the roll-off coefficient of the root raised cosine filter algorithm is 0.01, and a 6 GHz guard band is inserted at the zero frequency of the complex-valued double-sideband signal, that is, -3 GHz to 3 GHz, and the carrier signal power ratio is set to 8 dB. The complex-valued double-sideband 16-QAM signal is introduced with additive white Gaussian noise to simulate the optical fiber channel.

[0169] At the receiving end, the signal is reconstructed using the steps described above, and interference is eliminated using an iterative algorithm. Finally, after matched filtering and bit error rate calculation, we get Figure 5 The bit error performance shown ( Figure 5 (Figure 2 is a schematic diagram for comparing bit error performance under different optical signal-to-noise ratio conditions). Figure 5 The error performance comparison diagram of the present invention and other solutions under different optical signal-to-noise ratio conditions in the embodiment is shown. The dispersion diversity detection method in the prior art of "7, 23, 60 km" described in the figure.

[0170] Compared with the solution of using a single dispersive element to build an optical mixer, the present application can obtain a lower bit error rate and significantly improve the system performance. Compared with the dispersion diversity detection method, the present application reduces the use of two photodetectors and two analog-to-digital converters at the receiving end, while reducing the system cost, and still can obtain slightly better system performance. By optimizing the number of dispersive elements used and the dispersion value, the present application can greatly alleviate the impact of the frequency selective power fading effect caused by the dispersive element on the complex-valued double-sideband signal to be measured, thereby significantly improving the system performance.

[0171] In this embodiment, the transmitter performs pulse shaping on the complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulates the shaped complex-valued double-sideband signal based on a preset protection band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal. An additive Gaussian white noise channel introduces additive Gaussian white noise into the modulated complex-valued double-sideband signal to obtain a complex-valued double-sideband signal to be measured, which not only enhances the anti-interference ability of the signal, but also improves the transmission quality and accuracy of the signal.

[0172] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the signal reconstruction method of the present application. More simple transformations based on this technical concept are all within the scope of protection of the present application.

[0173] The present application provides a signal reconstruction device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the signal reconstruction method in the above-mentioned embodiment one.

[0174] Reference below Figure 8 , which shows a schematic diagram of the structure of a signal reconstruction device suitable for implementing an embodiment of the present application. The signal reconstruction device in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Desctions: tablet computers), PMPs (Portable Media Players: portable multimedia players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 8 The signal reconstruction device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0175] like Figure 8As shown, the signal reconstruction device may include a processing device 1001 (such as a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the signal reconstruction device are also stored. The processing device 1001, ROM1002 and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the signal reconstruction device to communicate with other devices wirelessly or by wire to exchange data. Although the figure shows a signal reconstruction device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0176] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0177] The signal reconstruction device provided by the present application adopts the signal reconstruction method in the above embodiment, which can solve the technical problem that the signal suffers from severe frequency selective power fading effect in the existing signal reconstruction system, resulting in reduced transmission performance. Compared with the prior art, the beneficial effects of the signal reconstruction device provided by the present application are the same as the beneficial effects of the signal reconstruction method provided by the above embodiment, and other technical features in the signal reconstruction device are the same as the features disclosed in the method of the previous embodiment, which will not be repeated here.

[0178] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0179] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0180] The present application provides a computer-readable storage medium having computer-readable program instructions (ie, computer programs) stored thereon, wherein the computer-readable program instructions are used to execute the signal reconstruction method in the above-mentioned embodiment.

[0181] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0182] The computer-readable storage medium carries one or more programs. When the one or more programs are executed by the signal reconstruction device, the signal reconstruction device: the first optical coupler divides the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal; the first photodetector performs square-law detection on the first complex-valued double-sideband signal to obtain a square-processed electrical signal; the optical mixer processes the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and a plurality of dispersion elements to obtain a dispersion-processed optical signal; the second photodetector converts the dispersion-processed optical signal into a dispersion-processed electrical signal; the first analog-to-digital converter performs sampling and quantization processing on the square-processed electrical signal to obtain a first digital signal; the second analog-to-digital converter performs sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal; the digital signal processing unit obtains an in-phase component of the information-bearing signal from the first digital signal, and obtains an orthogonal component of the information-bearing signal from the second digital signal; and the digital signal processing unit obtains a reconstructed signal according to the in-phase component of the information-bearing signal and the orthogonal component of the information-bearing signal.

[0183] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0184] The readable storage medium provided by the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned signal reconstruction method, and can solve the technical problem that the signal suffers from severe frequency selective power fading effects in the existing signal reconstruction system, resulting in reduced transmission performance. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present application are the same as the beneficial effects of the signal reconstruction method provided by the above-mentioned embodiment, and will not be repeated here.

[0185] The present application also provides a computer program product, including a computer program, which implements the steps of the above-mentioned signal reconstruction method when executed by a processor.

[0186] The computer program product provided by the present application can solve the technical problem that the signal suffers from severe frequency selective power fading effect in the existing signal reconstruction system, resulting in reduced transmission performance. Compared with the prior art, the beneficial effects of the computer program product provided by the present application are the same as the beneficial effects of the signal reconstruction method provided by the above embodiment, and will not be repeated here.

[0187] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present application.

Claims

1. A signal reconstruction system, characterized in that: The signal reconstruction system comprises: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter and a digital signal processing unit, wherein the optical mixer comprises a second optical coupler, a third optical coupler and a plurality of dispersion elements; The first optical coupler is used to divide the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal; The first photodetector is used to perform square-law detection on the first complex-valued double-sideband signal to obtain a squared electrical signal; The optical mixer is used to process the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and the plurality of dispersion elements to obtain a dispersion-processed optical signal; The second photodetector is used to convert the dispersion-processed optical signal into a dispersion-processed electrical signal; The first analog-to-digital converter is used to perform sampling and quantization processing on the squared electrical signal to obtain a first digital signal; The second analog-to-digital converter is used to perform sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal; The digital signal processing unit is used to obtain an information-bearing signal in-phase component from the first digital signal and to obtain an information-bearing signal orthogonal component from the second digital signal; The digital signal processing unit is further used to obtain a reconstructed signal according to the in-phase component of the information-bearing signal and the orthogonal component of the information-bearing signal.

2. The signal reconstruction system according to claim 1, characterized in that: The optical mixer is further configured to receive the second complex-valued double-sideband signal through the second optical coupler, and divide the second complex-valued double-sideband signal into multiple signals; The optical mixer is further used to process the multi-path signals in parallel through the multiple dispersion elements to generate signal components with different dispersion characteristics; The optical mixer is further used to combine the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information.

3. The signal reconstruction system according to claim 1, characterized in that: The digital signal processing unit is used to reconstruct the first digital signal based on a signal reconstruction algorithm to obtain an in-phase component of the information bearing signal; The digital signal processing unit is further used to reconstruct the second digital signal based on the time domain impulse responses of the multiple dispersion elements to obtain the orthogonal components of the information-bearing signal.

4. The signal reconstruction system according to any one of claims 1 to 3, characterized in that: The signal reconstruction system also includes a transmitter and an additive white Gaussian noise channel; The transmitter is used to perform pulse shaping on the complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulate the shaped complex-valued double-sideband signal based on a preset guard band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal; The additive white Gaussian noise channel is used to introduce additive white Gaussian noise into the modulated complex-valued double-sideband signal to obtain the complex-valued double-sideband signal to be measured.

5. The signal reconstruction system according to any one of claims 1 to 3, characterized in that: The digital signal processing unit is further used to eliminate interference in the reconstructed signal through a deep learning model or an iterative algorithm to obtain a reconstructed signal after elimination; The digital signal processing unit is further used to obtain an optimized reconstructed signal by performing matched filtering on the eliminated reconstructed signal.

6. A signal reconstruction method, characterized in that: The signal reconstruction method is applied to a signal reconstruction system, the system comprising: a first optical coupler, a first photodetector, an optical mixer, a second photodetector, a first analog-to-digital converter, a second analog-to-digital converter and a digital signal processing unit, the optical mixer comprising a second optical coupler, a third optical coupler and a plurality of dispersion elements; the method comprises: The first optical coupler divides the complex-valued double-sideband signal to be measured into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal; The first photodetector performs square-law detection on the first complex-valued double-sideband signal to obtain a squared electrical signal; The optical mixer processes the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and the plurality of dispersion elements to obtain a dispersion-processed optical signal; The second photodetector converts the dispersion-processed optical signal into a dispersion-processed electrical signal; The first analog-to-digital converter performs sampling and quantization processing on the squared electrical signal to obtain a first digital signal; The second analog-to-digital converter performs sampling and quantization processing on the dispersion-processed electrical signal to obtain a second digital signal; The digital signal processing unit obtains an information-bearing signal in-phase component from the first digital signal, and obtains an information-bearing signal orthogonal component from the second digital signal; The digital signal processing unit obtains a reconstructed signal according to the in-phase component of the information bearing signal and the quadrature component of the information bearing signal.

7. The signal reconstruction method according to claim 6, characterized in that: The step of the optical mixer processing the second complex-valued double-sideband signal through the second optical coupler, the third optical coupler and the plurality of dispersion elements to obtain a dispersion-processed optical signal comprises: The optical mixer receives the second complex-valued double-sideband signal through the second optical coupler, and divides the second complex-valued double-sideband signal into multiple signals; The optical mixer processes the multi-path signals in parallel through the multiple dispersion elements to generate signal components with different dispersion characteristics; The optical mixer combines the signal components through the third optical coupler to obtain a dispersion-processed optical signal containing orthogonal component information.

8. The signal reconstruction method according to claim 6, characterized in that: The step of the digital signal processing unit obtaining an in-phase component of an information-bearing signal from the first digital signal and obtaining an orthogonal component of an information-bearing signal from the second digital signal comprises: The digital signal processing unit reconstructs the first digital signal based on a signal reconstruction algorithm to obtain an in-phase component of an information-bearing signal; The digital signal processing unit reconstructs the second digital signal based on the time domain impulse responses of the multiple dispersion elements to obtain orthogonal components of information-bearing signals.

9. The signal reconstruction method according to any one of claims 6 to 8, characterized in that: The signal reconstruction system also includes a transmitter and an additive white Gaussian noise channel; Before the step of dividing the complex-valued double-sideband signal to be measured by the first optical coupler into a first complex-valued double-sideband signal and a second complex-valued double-sideband signal, the method further includes: The transmitter performs pulse shaping on the complex-valued double-sideband signal based on a root raised cosine filter algorithm to obtain a shaped complex-valued double-sideband signal, and modulates the shaped complex-valued double-sideband signal based on a preset guard band and a carrier signal power ratio to obtain a modulated complex-valued double-sideband signal; The additive white Gaussian noise channel introduces additive white Gaussian noise into the modulated complex-valued double-sideband signal to obtain the complex-valued double-sideband signal to be measured.

10. The signal reconstruction method according to any one of claims 6 to 8, characterized in that: After the step of obtaining the reconstructed signal according to the in-phase component of the information bearing signal and the orthogonal component of the information bearing signal by the digital signal processing unit, the step further includes: The digital signal processing unit eliminates interference in the reconstructed signal through a deep learning model or an iterative algorithm to obtain a reconstructed signal after elimination; The digital signal processing unit obtains an optimized reconstructed signal by performing matched filtering on the eliminated reconstructed signal.

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