WO2021031466A1 - Wave cutoff wavelength compensation method for multiview sar wave spectrum data fusion - Google Patents

Wave cutoff wavelength compensation method for multiview sar wave spectrum data fusion Download PDF

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WO2021031466A1
WO2021031466A1 PCT/CN2019/124305 CN2019124305W WO2021031466A1 WO 2021031466 A1 WO2021031466 A1 WO 2021031466A1 CN 2019124305 W CN2019124305 W CN 2019124305W WO 2021031466 A1 WO2021031466 A1 WO 2021031466A1
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wave
sar
spectrum
synchronization data
satellite
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French (fr)
Chinese (zh)
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万勇
戴永寿
张晓宇
李立刚
孙伟峰
周鹏
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中国石油大学(华东)
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques

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  • the present disclosure relates to the field of ocean wave observation technology, and in particular to a wave cut-off wavelength compensation method for fusion of multi-view SAR ocean wave spectrum data, SAR, Synthetic Aperture Radar, and synthetic aperture radar.
  • Ocean waves are small-scale wind-induced gravity waves that occur on the surface of the ocean, including wind waves and swells, and are also an important ocean dynamic process. Studying the generation and evolution mechanism of ocean waves, revealing its internal structure and external characteristics, has become an important research field in oceanography, and is of great significance to the construction of national defense, shipping, ports, and offshore oil platforms.
  • the common methods for obtaining ocean wave information mainly include numerical forecasting, field observation, and remote sensing observation.
  • Numerical forecasting mainly uses wave models to calculate and forecast the sea state information of the sea area; on-site observations mainly use buoys to measure and study the sea state of the sea area; remote sensing observations mainly use SAR, altimeter and scatterometer equipment to realize the observation of the sea state of the sea area.
  • SAR has a high spatial resolution, can work all-time and all-weather, and the observation results are not affected by underwater terrain, with multi-band and multi-polarization, and can realize large-scale ocean wave detection in space.
  • the problem of SAR cutting off wavelength for ocean wave observation is an inherent drawback of SAR observation of ocean waves. Few researchers at home and abroad have conducted in-depth research on the issue of wavelength cutoff.
  • the parameters that affect the cut-off wavelength include effective wave height, wind speed, SAR incident angle, range-speed ratio, wave orbit velocity, etc.
  • most studies on cut-off wavelength are devoted to mutual estimation of cut-off wavelength and the above-mentioned wave parameters, and there is no compensation for cut-off wavelength.
  • Related research The prerequisite for carrying out truncated wavelength compensation is the need for coordinated observation of satellite networks to obtain multi-directional SAR wave synchronization data. Because the degree of azimuth truncation caused by different SAR observation directions is different, fusion of synchronized data with different truncation degrees according to the weight can effectively compensate for the impact of azimuth truncation.
  • the current satellites in orbit cannot achieve simultaneous observation of the same sea area by multiple SARs, and cannot obtain synchronized data of multiple viewing directions. Therefore, it needs to be obtained through imaging simulation to lay the foundation for future networked SAR satellite observation of ocean waves.
  • the current research is mostly single-satellite SAR imaging simulation, and multi-satellite imaging simulation has not yet been studied.
  • the current method of obtaining sea surface SAR images is to directly simulate the sea surface SAR images based on the sea surface model, the sea surface electromagnetic scattering model and the SAR imaging mechanism of the sea waves.
  • this method avoids the calculation of complex raw SAR data, it cannot fully reflect the characteristics of the SAR system.
  • the speed bunching effect cannot be introduced in the sea surface echo signal generation process, and the accuracy of the generated sea echo signal is limited. In line with the physical mechanism of the real sea.
  • the present disclosure provides a wave truncated wavelength compensation method for fusion of multi-view SAR wave spectrum data; it is of great significance for realizing the complete detection of wave information, and the commercial observation of waves by SAR;
  • the present disclosure provides a wave truncated wavelength compensation method for fusion of multi-view SAR wave spectrum data
  • Wave cut-off wavelength compensation method based on fusion of multi-view SAR wave spectrum data includes:
  • the MPI algorithm is used to invert the single-satellite SAR wave synchronization data to obtain the optimal wave spectrum of each single-satellite SAR wave synchronization data, and estimate the cut-off wavelength of each single-satellite wave synchronization data;
  • the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data is determined.
  • the optimal value obtained by the inversion is The wave spectrum is data fused, and the optimal wave spectrum after the multi-satellite fusion is obtained after the fusion.
  • the cutoff wavelengths corresponding to the optimal wave spectrum before and after the fusion are respectively estimated to realize the cutoff wavelength compensation.
  • the sea surface SAR image is indirectly obtained by simulating the sea surface SAR echo signal. It has the advantages of not relying on the imaging model and high accuracy of the imaging result. It simulates the real working process of the SAR receiver and can obtain the original echo signal and the generated sea surface echo signal. The most accurate.
  • Multi-satellite SAR imaging simulation can lay the foundation for future networked satellite observation of ocean waves, and the obtained multi-directional SAR ocean wave synchronization data can be used as a basic data source for related research.
  • the proposed multi-satellite wave spectrum data fusion method can effectively compensate the cut-off wavelength through data fusion.
  • the proposed method of truncated wavelength compensation can make the observed ocean wave information more complete.
  • the virtual satellite network simulated in the present disclosure can provide a reference for the networked SAR satellite to observe ocean waves.
  • the obtained multi-view SAR ocean wave synchronization data can be used in SAR system design and imaging algorithm research; the multi-satellite ocean wave spectrum data fusion method can compensate for truncation The non-linear effect of wavelength; the proposed method can enable SAR to observe more complete ocean wave information, and realize the operational observation of ocean waves by SAR.
  • Figure 1 is a flow chart of the method of the first embodiment
  • Figure 2(a) is a schematic diagram of the observed SAR spectrum of the first embodiment
  • Figure 2(b) is a schematic diagram of the initial guessing of the wave spectrum of the first embodiment
  • Figure 2(c) is a schematic diagram of the optimal wave spectrum of the first embodiment
  • Figure 2(d) is a schematic diagram of the proper SAR spectrum of the first embodiment.
  • the initial guessing of the wave spectrum is to retrieve the initial input of the most suitable wave spectrum, which comes from a fixed wave spectrum or pattern spectrum;
  • the optimal wave spectrum is the output obtained from the inversion of SAR data by the MPI algorithm.
  • the core idea of the MPI algorithm is to construct a value function. After the value function is minimized, the iteration is completed. The output wave spectrum after the iteration is called the optimal wave spectrum.
  • the sea surface electromagnetic backscattering coefficient can also be called the sea surface electromagnetic backscattering cross section.
  • the scattering surface is the sea surface electromagnetic backscattering cross section, usually called Is the backscattering coefficient.
  • Range Doppler The full English name of the RD algorithm: Range Doppler; Chinese meaning: Range Doppler.
  • this embodiment provides a wave cut-off wavelength compensation method for fusion of multi-view SAR wave spectrum data
  • the wave truncated wavelength compensation method based on fusion of multi-view SAR wave spectrum data includes:
  • S1 Perform multi-directional SAR sea wave synchronization data simulation, and obtain a virtual satellite network containing multiple SAR satellites through the simulation, and obtain the wave synchronization data of each SAR satellite; and then obtain the multi-directional SAR wave synchronization data;
  • S3 Determine the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data according to the relationship between the azimuth angle and the cut-off wavelength, and invert the inversion based on the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data
  • Data fusion is performed on the optimal wave spectrum, and the optimal wave spectrum after the multi-satellite fusion is obtained after the fusion.
  • the cutoff wavelengths corresponding to the optimal wave spectrum before and after the fusion are respectively estimated to realize the cutoff wavelength compensation .
  • the multi-view SAR wave synchronization data simulation simulation is performed, and the simulation obtains a virtual satellite network including multiple SAR satellites, and obtains the wave synchronization data of each SAR satellite; and then obtains the multi-view SAR Wave synchronization data; specific steps include:
  • S11 Carry out multi-view SAR wave synchronization data simulation simulation, and obtain a virtual satellite network containing multiple SAR satellites; simulate and generate a wave spectrum; based on the wave spectrum generated by the simulation, simulate a two-dimensional sea surface;
  • S14 Process the sea surface echo signal to obtain multi-view SAR sea wave synchronization data.
  • the simulation to generate the ocean wave spectrum is to input the wave number, direction, and wind speed to the two-dimensional PM wave number direction spectrum to realize the simulation and generation of the ocean wave spectrum.
  • the two-dimensional PM wavenumber direction spectrum is used to realize the simulation and generation of ocean wave spectrum; the specific steps are as follows:
  • S PM (k, ⁇ ) represents the wave spectrum generated by the simulation.
  • the simulation to generate a two-dimensional sea surface is to input a two-dimensional PM wave number direction spectrum into the Monte Carlo algorithm to simulate and generate a two-dimensional sea surface.
  • the specific steps are: first, generate two-dimensional Gaussian white noise, and secondly, use the two-dimensional PM wavenumber direction spectrum to linearly filter the white noise to obtain the Fourier transform of the sea surface height fluctuation function, Do inverse Fourier transform on it to get the two-dimensional sea surface.
  • Monte Carlo algorithm is used to simulate and generate a two-dimensional sea surface; the specific steps are as follows:
  • L x represents the length of the two-dimensional random rough surface to be generated in the x direction
  • L y represents the length of the two-dimensional random rough surface to be generated in the y direction.
  • It is a two-dimensional PM wavenumber spectrum, which can be obtained by conversion of a two-dimensional PM wavenumber direction spectrum
  • Is the wave number in the distance direction
  • N(0,1) represents a random number with a mean value of 0 and a variance of 1 that obeys the Gaussian distribution.
  • the calculation of the electromagnetic backscattering coefficient of the sea surface is performed by using a two-scale electromagnetic scattering model.
  • the dual-scale electromagnetic scattering model is used to calculate the electromagnetic backscattering coefficient of the sea surface:
  • k represents the SAR electromagnetic scattering wave number
  • ⁇ ′ i is the incident angle of radar observation
  • ⁇ represents the dielectric constant of sea water, which can be calculated by the Debye formula, taking the commonly used value 59.61-34.37i
  • U VV is the vertical polarization factor.
  • the generating of the echo signal of the two-dimensional sea surface is to generate the echo signal of the two-dimensional sea surface by using a time-domain echo algorithm.
  • ⁇ is the backscattering cross section of the point target
  • ⁇ is the antenna bidirectional amplitude weighting
  • ⁇ n is the nth pulse time of SAR transmission.
  • sea surface echo signal is processed to obtain multi-view SAR sea wave synchronization data; the specific steps are:
  • the RD imaging algorithm is applied to process the echo signal to obtain the SAR wave synchronization data of a single view direction.
  • the simulation obtains multi-view SAR wave synchronization data.
  • Multiple SARs can be three, four, five, or six.
  • the MPI algorithm is used to invert the single-satellite SAR wave synchronization data to obtain the optimal wave spectrum of the single-satellite SAR wave synchronization data; the specific steps include:
  • the MPI algorithm describes the mapping relationship between the two-dimensional ocean wave spectrum and the SAR image spectrum. Through initial guessing of the ocean wave spectrum, the value function is constructed, and after the value function is minimized through iteration, the optimal ocean wave spectrum and the optimal SAR spectrum are output.
  • the value function is defined as:
  • Multi-satellite wave spectrum data fusion is the basis of truncated wavelength compensation. Before data fusion, it is first necessary to clarify the relationship between the azimuth angle (the angle between the wave propagation direction and the SAR azimuth direction) and the cutoff wavelength, which is the basis for data fusion.
  • ⁇ represents the range-speed ratio
  • R is the slant distance between the SAR platform and the imaging target
  • V is the operating speed of the SAR platform.
  • ⁇ is the SAR incident angle
  • k r is the component of the wavenumber matrix k in the distance direction
  • F(k) is the wavenumber spectrum of the sea.
  • the azimuth angle and cutoff wavelength of the SAR wave synchronization data are shown in Table 1.
  • the estimated cut-off wavelength of the wave spectrum after fusion is 195.072m, which is smaller than the cut-off wavelength value before fusion, which verifies that the proposed data fusion method is effective and realizes the compensation of the cut-off wavelength.

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  • Radar, Positioning & Navigation (AREA)
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Abstract

A wave cutoff wavelength compensation method for Multiview SAR wave spectrum data fusion, comprising: performing a Multiview SAR wave synchronous data simulation to acquire Multiview SAR wave synchronous data; using an MPI algorithm in the inversion of individual satellite SAR wave synchronous data on the basis of the Multiview SAR wave synchronous data to obtain an optical wave spectrum for the individual satellite SAR wave synchronous data, estimating a cutoff wavelength for the individual satellite SAR wave synchronous data; determining an optimal wave spectrum fusion weight for the individual satellite SAR wave synchronous data on the basis of relations between azimuths and cutoff wavelengths, performing, on the basis of the optimal wave spectrum fusion weight for the individual satellite SAR wave synchronous data, data fusion with respect to the optimal wave spectrum obtained by inversion, when fused, obtaining a multiple satellite-fused optimal wave spectrum, and respectively estimating, on the basis of the multiple satellite-fused optimal wave spectrum, cutoff wavelengths corresponding to pre-fusion optimal spectra, thus implementing cutoff wave compensation.

Description

多视向SAR海浪谱数据融合的海浪截断波长补偿方法Wave truncated wavelength compensation method based on fusion of multi-view SAR wave spectrum data 技术领域Technical field
本公开涉及海浪观测技术领域，特别是涉及多视向SAR海浪谱数据融合的海浪截断波长补偿方法，SAR，Synthetic Aperture Radar，合成孔径雷达。The present disclosure relates to the field of ocean wave observation technology, and in particular to a wave cut-off wavelength compensation method for fusion of multi-view SAR ocean wave spectrum data, SAR, Synthetic Aperture Radar, and synthetic aperture radar.
背景技术Background technique
本部分的陈述仅仅是提到了与本公开相关的背景技术，并不必然构成现有技术。The statements in this section merely mention background technologies related to the present disclosure, and do not necessarily constitute prior art.
海浪是发生在海洋表面的一种小尺度的风生重力波，包括风浪和涌浪，同时也是一种重要的海洋动力过程。研究海浪的生成和演化机制，揭示其内部结构和外在特征，成为海洋学中的一个重要研究领域，对于国防、航运、港口以及海上石油平台的建设等都具有重要意义。获取海浪信息的常用方法主要有数值预报、现场观测以及遥感观测等。数值预报主要是利用海浪模式计算并预报海域的海况信息；现场观测主要是利用浮标实测研究海域海况；遥感观测主要是利用SAR、高度计以及散射计等设备实现海域海况的观测。与其他手段相比，SAR的空间分辨率很高，可以全天时、全天候工作，并且观测结果不受水下地形影响，具有多波段、多极化，可以实现空间大范围海浪的探测。Ocean waves are small-scale wind-induced gravity waves that occur on the surface of the ocean, including wind waves and swells, and are also an important ocean dynamic process. Studying the generation and evolution mechanism of ocean waves, revealing its internal structure and external characteristics, has become an important research field in oceanography, and is of great significance to the construction of national defense, shipping, ports, and offshore oil platforms. The common methods for obtaining ocean wave information mainly include numerical forecasting, field observation, and remote sensing observation. Numerical forecasting mainly uses wave models to calculate and forecast the sea state information of the sea area; on-site observations mainly use buoys to measure and study the sea state of the sea area; remote sensing observations mainly use SAR, altimeter and scatterometer equipment to realize the observation of the sea state of the sea area. Compared with other methods, SAR has a high spatial resolution, can work all-time and all-weather, and the observation results are not affected by underwater terrain, with multi-band and multi-polarization, and can realize large-scale ocean wave detection in space.
在实现本公开的过程中，发明人发现现有技术中存在以下技术问题：In the process of implementing the present disclosure, the inventor found the following technical problems in the prior art:
由于速度聚束调制的影响，SAR观测海浪存在方位向截断的现象，导致SAR观测到的主要是长波涌浪的结果，而且只能观测到波长大于截断波长的海浪，无法观测到完整的海浪信息。这是单星SAR观测海浪的致命缺点，极大的限制了SAR对海浪的观测能力和观测的完整性，也一定程度上限制了SAR 对海浪业务化观测的实现。针对单星SAR观测海浪存在截断波长的问题，未来可通过组网SAR卫星协同观测的方式在一定程度上解决，但是由于技术水平的限制，目前的在轨卫星无法实现同时观测同一块海域，获取不到多视向SAR海浪同步数据，无法实现截断波长的补偿。Due to the influence of velocity bunching modulation, SAR observation waves are truncated in azimuth direction. As a result, SAR observations are mainly the result of long-wave swells, and only waves with wavelengths greater than the cut-off wavelength can be observed, and complete wave information cannot be observed. . This is the fatal shortcoming of single-satellite SAR observation of ocean waves, which greatly limits the SAR's ability to observe ocean waves and the completeness of observations, and also limits the realization of SAR's commercialized ocean wave observations to a certain extent. In view of the problem of truncated wavelength in single-satellite SAR observation of ocean waves, it can be solved to a certain extent through the collaborative observation of networked SAR satellites in the future. However, due to technical limitations, current satellites in orbit cannot simultaneously observe the same sea area. Without multi-view SAR sea wave synchronization data, it is impossible to realize the compensation of the cut-off wavelength.
SAR对海浪观测产生截断波长的问题，是SAR观测海浪的一个固有弊端，国内外鲜少有学者针对截断波长的问题进行深入研究。影响截断波长的参数有有效波高、风速、SAR入射角、距离速度比、波轨道速度等，目前针对截断波长的研究大都致力于截断波长与上述海浪参数的互相估算，并没有关于截断波长补偿的相关研究。开展截断波长补偿工作的前提是需要卫星组网协同观测获取多视向SAR海浪同步数据。因为不同的SAR观测方向带来的方位向截断程度是不同的，不同截断程度的同步数据按权值进行融合可以有效地弥补方位向截断产生的影响。The problem of SAR cutting off wavelength for ocean wave observation is an inherent drawback of SAR observation of ocean waves. Few scholars at home and abroad have conducted in-depth research on the issue of wavelength cutoff. The parameters that affect the cut-off wavelength include effective wave height, wind speed, SAR incident angle, range-speed ratio, wave orbit velocity, etc. At present, most studies on cut-off wavelength are devoted to mutual estimation of cut-off wavelength and the above-mentioned wave parameters, and there is no compensation for cut-off wavelength. Related research. The prerequisite for carrying out truncated wavelength compensation is the need for coordinated observation of satellite networks to obtain multi-directional SAR wave synchronization data. Because the degree of azimuth truncation caused by different SAR observation directions is different, fusion of synchronized data with different truncation degrees according to the weight can effectively compensate for the impact of azimuth truncation.
目前的在轨卫星无法实现多颗SAR对同一海域的同时观测，获取不到多视向同步数据，因此需要通过成像仿真的方式获取，为未来组网SAR卫星观测海浪奠定基础。然而目前的研究大都是单星SAR成像仿真，多星成像仿真尚未有研究。运用仿真的手段，目前获取海面SAR图像的方法是根据海面模型、海面电磁散射模型以及SAR对海浪的成像机制直接仿真得到海面SAR图像。该方法虽然避免了复杂原始SAR数据的计算，但不能较全面的反映SAR***特征，尤其是在海面回波信号生成过程中不能引入速度聚束效应，生成的海面回波信号精度受限，不符合真实海面的物理机制。The current satellites in orbit cannot achieve simultaneous observation of the same sea area by multiple SARs, and cannot obtain synchronized data of multiple viewing directions. Therefore, it needs to be obtained through imaging simulation to lay the foundation for future networked SAR satellite observation of ocean waves. However, the current research is mostly single-satellite SAR imaging simulation, and multi-satellite imaging simulation has not yet been studied. Using simulation methods, the current method of obtaining sea surface SAR images is to directly simulate the sea surface SAR images based on the sea surface model, the sea surface electromagnetic scattering model and the SAR imaging mechanism of the sea waves. Although this method avoids the calculation of complex raw SAR data, it cannot fully reflect the characteristics of the SAR system. In particular, the speed bunching effect cannot be introduced in the sea surface echo signal generation process, and the accuracy of the generated sea echo signal is limited. In line with the physical mechanism of the real sea.
发明内容Summary of the invention
为了解决现有技术的不足，本公开提供了多视向SAR海浪谱数据融合的 海浪截断波长补偿方法；对于实现海浪信息的完整探测、SAR对海浪业务化观测等具有重要的意义；In order to solve the shortcomings of the prior art, the present disclosure provides a wave truncated wavelength compensation method for fusion of multi-view SAR wave spectrum data; it is of great significance for realizing the complete detection of wave information, and the commercial observation of waves by SAR;
本公开提供了多视向SAR海浪谱数据融合的海浪截断波长补偿方法；The present disclosure provides a wave truncated wavelength compensation method for fusion of multi-view SAR wave spectrum data;
多视向SAR海浪谱数据融合的海浪截断波长补偿方法，包括：Wave cut-off wavelength compensation method based on fusion of multi-view SAR wave spectrum data includes:
进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫星的虚拟卫星组网，获得每颗SAR卫星的海浪同步数据；进而获得多视向SAR海浪同步数据；Carry out multi-directional SAR wave synchronization data simulation simulation, and obtain a virtual satellite network containing multiple SAR satellites, and obtain the wave synchronization data of each SAR satellite; and then obtain the multi-view SAR wave synchronization data;
基于多视向SAR海浪同步数据，运用MPI算法对各单星SAR海浪同步数据进行反演，得到各单星SAR海浪同步数据的最适海浪谱，估算各单星海浪同步数据的截断波长；Based on the multi-directional SAR wave synchronization data, the MPI algorithm is used to invert the single-satellite SAR wave synchronization data to obtain the optimal wave spectrum of each single-satellite SAR wave synchronization data, and estimate the cut-off wavelength of each single-satellite wave synchronization data;
根据方位角与截断波长的关系确定各单星SAR海浪同步数据的最适海浪谱的融合权值，根据各单星SAR海浪同步数据的最适海浪谱的融合权值对反演得到的最适海浪谱进行数据融合，融合之后得到多星融合之后的最适海浪谱，基于多星融合之后的最适海浪谱，分别估算融合前后的最适海浪谱对应的截断波长，实现截断波长补偿。According to the relationship between the azimuth angle and the cut-off wavelength, the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data is determined. According to the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data, the optimal value obtained by the inversion is The wave spectrum is data fused, and the optimal wave spectrum after the multi-satellite fusion is obtained after the fusion. Based on the optimal wave spectrum after the multi-satellite fusion, the cutoff wavelengths corresponding to the optimal wave spectrum before and after the fusion are respectively estimated to realize the cutoff wavelength compensation.
与现有技术相比，本公开的有益效果是：Compared with the prior art, the beneficial effects of the present disclosure are:
通过模拟生成海面SAR回波信号间接得到海面SAR图像，具有不依赖成像模型、成像结果精度高等优势，模拟的是SAR接收机的真实工作过程，能够获取原始回波信号，生成的海面回波信号最为准确。The sea surface SAR image is indirectly obtained by simulating the sea surface SAR echo signal. It has the advantages of not relying on the imaging model and high accuracy of the imaging result. It simulates the real working process of the SAR receiver and can obtain the original echo signal and the generated sea surface echo signal. The most accurate.
多星SAR成像仿真可为未来组网卫星观测海浪奠定基础，获得的多视向SAR海浪同步数据可以作为相关研究的基础数据源。Multi-satellite SAR imaging simulation can lay the foundation for future networked satellite observation of ocean waves, and the obtained multi-directional SAR ocean wave synchronization data can be used as a basic data source for related research.
提出的多星海浪谱数据融合方法能够通过数据融合的方式有效的进行截断 波长的补偿。The proposed multi-satellite wave spectrum data fusion method can effectively compensate the cut-off wavelength through data fusion.
截断波长补偿方法的提出能够使观测到的海浪信息更加完整。The proposed method of truncated wavelength compensation can make the observed ocean wave information more complete.
本公开仿真的虚拟卫星组网可以为组网SAR卫星观测海浪提供借鉴，获得的多视向SAR海浪同步数据可用于SAR***设计、成像算法研究等方面；多星海浪谱数据融合方法能够补偿截断波长产生的非线性影响；提出的方法能够使SAR观测到更加完整的海浪信息，实现SAR对海浪的业务化观测。The virtual satellite network simulated in the present disclosure can provide a reference for the networked SAR satellite to observe ocean waves. The obtained multi-view SAR ocean wave synchronization data can be used in SAR system design and imaging algorithm research; the multi-satellite ocean wave spectrum data fusion method can compensate for truncation The non-linear effect of wavelength; the proposed method can enable SAR to observe more complete ocean wave information, and realize the operational observation of ocean waves by SAR.
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构成本申请的一部分的说明书附图用来提供对本申请的进一步理解，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。The drawings of the specification forming a part of the application are used to provide a further understanding of the application, and the exemplary embodiments and descriptions of the application are used to explain the application and do not constitute an improper limitation of the application.
图1为第一个实施例的方法流程图；Figure 1 is a flow chart of the method of the first embodiment;
图2(a)为第一个实施例的观测SAR谱示意图；Figure 2(a) is a schematic diagram of the observed SAR spectrum of the first embodiment;
图2(b)为第一个实施例的初猜海浪谱示意图；Figure 2(b) is a schematic diagram of the initial guessing of the wave spectrum of the first embodiment;
图2(c)为第一个实施例的最适海浪谱示意图；Figure 2(c) is a schematic diagram of the optimal wave spectrum of the first embodiment;
图2(d)为第一个实施例的适SAR谱示意图。Figure 2(d) is a schematic diagram of the proper SAR spectrum of the first embodiment.
具体实施方式detailed description
应该指出，以下详细说明都是示例性的，旨在对本申请提供进一步的说明。除非另有指明，本文使用的所有技术和科学术语具有与本申请所属技术领域的普通技术人员通常理解的相同含义。It should be pointed out that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.
需要注意的是，这里所使用的术语仅是为了描述具体实施方式，而非意图限制根据本申请的示例性实施方式。如在这里所使用的，除非上下文另外明确指出，否则单数形式也意图包括复数形式，此外，还应当理解的是，当在本说明书中使用术语“包含”和/或“包括”时，其指明存在特征、步骤、操作、器件、 组件和/或它们的组合。It should be noted that the terms used here are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and/or "including" are used in this specification, they indicate There are features, steps, operations, devices, components, and/or combinations thereof.
由于速度聚束调制在SAR成像过程中产生的非线性影响，单星SAR观测海浪会产生方位向截断的现象，导致SAR观测到的主要是长波涌浪的结果，而且只能观测到波长大于截断波长的海浪，波长小于截断波长的海浪信息丢失，无法观测到完整的海浪信息。Due to the nonlinear effect of velocity bunching modulation in the SAR imaging process, single-satellite SAR observations of ocean waves will produce azimuth truncation, which leads to SAR observations that are mainly the result of long wave surges, and only the wavelength is greater than the truncation. Waves with wavelengths and wave information with a wavelength smaller than the cutoff wavelength are lost, and complete wave information cannot be observed.
专业术语介绍：Introduction of professional terms:
MPI，英文全称：Max Planck Institute；中文含义：马克斯-普朗克研究所，简称：马普所；MPI, full English name: Max Planck Institute; Chinese meaning: Max Planck Institute, abbreviation: Max Planck Institute;
初猜海浪谱是为了反演最适海浪谱的初始输入，来自于固定的海浪谱或者模式的谱；The initial guessing of the wave spectrum is to retrieve the initial input of the most suitable wave spectrum, which comes from a fixed wave spectrum or pattern spectrum;
最适海浪谱，是由MPI算法反演SAR数据得到的输出，MPI算法的核心思想是构造价值函数，价值函数最小化后完成迭代，迭代完成后输出的海浪谱称为最适海浪谱。The optimal wave spectrum is the output obtained from the inversion of SAR data by the MPI algorithm. The core idea of the MPI algorithm is to construct a value function. After the value function is minimized, the iteration is completed. The output wave spectrum after the iteration is called the optimal wave spectrum.
海面电磁后向散射系数，又可以称为海面电磁后向散射截面，当SAR朝海面发射电磁波时，接收的是被散射面散射后的电磁波，该散射面就是海面电磁后向散射截面，通常称为后向散射系数。The sea surface electromagnetic backscattering coefficient can also be called the sea surface electromagnetic backscattering cross section. When the SAR emits electromagnetic waves toward the sea surface, it receives the electromagnetic waves scattered by the scattering surface. The scattering surface is the sea surface electromagnetic backscattering cross section, usually called Is the backscattering coefficient.
RD算法的英文全称：Range Doppler；中文含义：距离多普勒。The full English name of the RD algorithm: Range Doppler; Chinese meaning: Range Doppler.
实施例一，本实施例提供了多视向SAR海浪谱数据融合的海浪截断波长补偿方法；In the first embodiment, this embodiment provides a wave cut-off wavelength compensation method for fusion of multi-view SAR wave spectrum data;
如图1所示，多视向SAR海浪谱数据融合的海浪截断波长补偿方法，包括：As shown in Figure 1, the wave truncated wavelength compensation method based on fusion of multi-view SAR wave spectrum data includes:
S1：进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫 星的虚拟卫星组网，获得每颗SAR卫星的海浪同步数据；进而获得多视向SAR海浪同步数据；S1: Perform multi-directional SAR sea wave synchronization data simulation, and obtain a virtual satellite network containing multiple SAR satellites through the simulation, and obtain the wave synchronization data of each SAR satellite; and then obtain the multi-directional SAR wave synchronization data;
S2：基于多视向SAR海浪同步数据，运用MPI算法对各单星SAR海浪同步数据进行反演，得到各单星SAR海浪同步数据的最适海浪谱，估算各单星海浪同步数据的截断波长；S2: Based on the multi-directional SAR wave synchronization data, use the MPI algorithm to invert the single-satellite SAR wave synchronization data, obtain the optimal wave spectrum of the single-satellite SAR wave synchronization data, and estimate the cut-off wavelength of the single-satellite wave synchronization data ；
S3：根据方位角与截断波长的关系确定各单星SAR海浪同步数据的最适海浪谱的融合权值，根据各单星SAR海浪同步数据的最适海浪谱的融合权值对反演得到的最适海浪谱进行数据融合，融合之后得到多星融合之后的最适海浪谱，基于多星融合之后的最适海浪谱，分别估算融合前后的最适海浪谱对应的截断波长，实现截断波长补偿。S3: Determine the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data according to the relationship between the azimuth angle and the cut-off wavelength, and invert the inversion based on the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data Data fusion is performed on the optimal wave spectrum, and the optimal wave spectrum after the multi-satellite fusion is obtained after the fusion. Based on the optimal wave spectrum after the multi-satellite fusion, the cutoff wavelengths corresponding to the optimal wave spectrum before and after the fusion are respectively estimated to realize the cutoff wavelength compensation .
作为一个或多个实施例，所述进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫星的虚拟卫星组网，获得每颗SAR卫星的海浪同步数据；进而获得多视向SAR海浪同步数据；具体步骤包括：As one or more embodiments, the multi-view SAR wave synchronization data simulation simulation is performed, and the simulation obtains a virtual satellite network including multiple SAR satellites, and obtains the wave synchronization data of each SAR satellite; and then obtains the multi-view SAR Wave synchronization data; specific steps include:
S11：进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫星的虚拟卫星组网；模拟生成海浪谱；基于模拟生成的海浪谱，模拟生成二维海面；S11: Carry out multi-view SAR wave synchronization data simulation simulation, and obtain a virtual satellite network containing multiple SAR satellites; simulate and generate a wave spectrum; based on the wave spectrum generated by the simulation, simulate a two-dimensional sea surface;
S12：基于二维海面，计算海面电磁后向散射系数；S12: Based on the two-dimensional sea surface, calculate the sea surface electromagnetic backscattering coefficient;
S13：基于海面电磁后向散射系数，生成二维海面的回波信号；S13: Generate a two-dimensional sea surface echo signal based on the sea surface electromagnetic backscattering coefficient;
S14：对海面回波信号进行处理，得到多视向SAR海浪同步数据。S14: Process the sea surface echo signal to obtain multi-view SAR sea wave synchronization data.
进一步地，所述模拟生成海浪谱，是向二维PM波数方向谱输入波数、方向和风速，实现模拟生成海浪谱。Further, the simulation to generate the ocean wave spectrum is to input the wave number, direction, and wind speed to the two-dimensional PM wave number direction spectrum to realize the simulation and generation of the ocean wave spectrum.
进一步地，所述采用二维PM波数方向谱实现模拟生成海浪谱；具体步骤 如下：Further, the two-dimensional PM wavenumber direction spectrum is used to realize the simulation and generation of ocean wave spectrum; the specific steps are as follows:
Figure PCTCN2019124305-appb-000001
Figure PCTCN2019124305-appb-000001
其中，a＝0.0081；b＝0.74；g 0为重力加速度，取9.81；K代表波数；U 19.5是海面19.5m高度处的风速；φ是海浪传播方向；φ m是主波波向，主波波向取值为风向角；φ-φ m代表的是海浪方向角，即海浪传播方向与风向的夹角，S PM(k,φ)表示模拟生成的海浪谱。 Among them, a = 0.0081; b = 0.74; g 0 is the acceleration of gravity, taking 9.81; K is the wave number; U 19.5 is the wind speed at the height of 19.5m on the sea surface; φ is the wave propagation direction; φ m is the main wave direction, the main wave The wave direction is taken as the wind direction angle; φ-φ m represents the wave direction angle, that is, the angle between the wave propagation direction and the wind direction. S PM (k, φ) represents the wave spectrum generated by the simulation.
进一步地，所述模拟生成二维海面，是向蒙特卡洛算法中输入二维PM波数方向谱，模拟生成二维海面。Further, the simulation to generate a two-dimensional sea surface is to input a two-dimensional PM wave number direction spectrum into the Monte Carlo algorithm to simulate and generate a two-dimensional sea surface.
进一步地，所述模拟生成二维海面，具体步骤是：首先，生成二维高斯白噪声，其次，运用二维PM波数方向谱对白噪声进行线性滤波，得到海面高度起伏函数的傅里叶变换，对其做傅里叶逆变换即可得到二维海面。Further, the simulation to generate a two-dimensional sea surface, the specific steps are: first, generate two-dimensional Gaussian white noise, and secondly, use the two-dimensional PM wavenumber direction spectrum to linearly filter the white noise to obtain the Fourier transform of the sea surface height fluctuation function, Do inverse Fourier transform on it to get the two-dimensional sea surface.
进一步地，采用蒙特卡洛算法模拟生成二维海面；具体步骤如下：Further, Monte Carlo algorithm is used to simulate and generate a two-dimensional sea surface; the specific steps are as follows:
海面高度起伏函数f(x m,y n)的表达公式： The expression formula of the sea level fluctuation function f(x m ,y n ):
Figure PCTCN2019124305-appb-000002
Figure PCTCN2019124305-appb-000002
其中，L x代表要产生的二维随机粗糙面在x方向的长度，L y代表要产生的二维随机粗糙面在y方向的长度，
Figure PCTCN2019124305-appb-000003
为二维PM波数谱，可由二维PM波数方向谱转换得到；
Figure PCTCN2019124305-appb-000004
为距离向的波数；
Figure PCTCN2019124305-appb-000005
为方位向的波数；N(0,1)表示均值为0、方差为1的服从高斯分布的随机数。 Among them, L x represents the length of the two-dimensional random rough surface to be generated in the x direction, and L y represents the length of the two-dimensional random rough surface to be generated in the y direction.
Figure PCTCN2019124305-appb-000003
It is a two-dimensional PM wavenumber spectrum, which can be obtained by conversion of a two-dimensional PM wavenumber direction spectrum;
Figure PCTCN2019124305-appb-000004
Is the wave number in the distance direction;
Figure PCTCN2019124305-appb-000005
Is the wave number in the azimuth direction; N(0,1) represents a random number with a mean value of 0 and a variance of 1 that obeys the Gaussian distribution.
其中，among them,
Figure PCTCN2019124305-appb-000006
Figure PCTCN2019124305-appb-000006
进一步地，所述计算海面电磁后向散射系数，是选用双尺度电磁散射模型来进行计算。Further, the calculation of the electromagnetic backscattering coefficient of the sea surface is performed by using a two-scale electromagnetic scattering model.
进一步地，选用双尺度电磁散射模型计算海面电磁后向散射系数：Furthermore, the dual-scale electromagnetic scattering model is used to calculate the electromagnetic backscattering coefficient of the sea surface:
Figure PCTCN2019124305-appb-000007
Figure PCTCN2019124305-appb-000007
Figure PCTCN2019124305-appb-000008
Figure PCTCN2019124305-appb-000008
其中，k代表SAR电磁散射波数；θ′ i为雷达观测入射角；ε代表海水介电常数，可由Debye公式计算得到，取常用值59.61-34.37i；U VV是垂直极化因子。 Among them, k represents the SAR electromagnetic scattering wave number; θ′ i is the incident angle of radar observation; ε represents the dielectric constant of sea water, which can be calculated by the Debye formula, taking the commonly used value 59.61-34.37i; U VV is the vertical polarization factor.
进一步地，所述生成二维海面的回波信号，是运用时域回波算法生成二维海面的回波信号。Further, the generating of the echo signal of the two-dimensional sea surface is to generate the echo signal of the two-dimensional sea surface by using a time-domain echo algorithm.
进一步地，运用时域回波算法生成海面回波信号：Further, use the time-domain echo algorithm to generate sea echo signals:
Figure PCTCN2019124305-appb-000009
Figure PCTCN2019124305-appb-000009
Figure PCTCN2019124305-appb-000010
Figure PCTCN2019124305-appb-000010
n＝1,2,3…N；m＝1,2,3…Mn＝1,2,3...N; m＝1,2,3...M
其中，σ为点目标的后向散射截面,ω表示天线双向幅度加权，τ n表示SAR发射第n个脉冲时间。exp[jπK r(t-n·PRT-2R(s；r)/C) 2]为chirp分量，决定距离向分辨率，
Figure PCTCN2019124305-appb-000011
为doppler分量，决定方位向分辨率。 Among them, σ is the backscattering cross section of the point target, ω is the antenna bidirectional amplitude weighting, and τ n is the nth pulse time of SAR transmission. exp[jπK r (tn·PRT-2R(s;r)/C) 2 ] is the chirp component, which determines the range resolution,
Figure PCTCN2019124305-appb-000011
Is the doppler component and determines the azimuth resolution.
进一步地，所述对海面回波信号进行处理，得到多视向SAR海浪同步数据；具体步骤为：Further, the sea surface echo signal is processed to obtain multi-view SAR sea wave synchronization data; the specific steps are:
在单颗SAR的工作模式为正侧视时，应用RD成像算法处理回波信号得到单个视向的SAR海浪同步数据。When the working mode of a single SAR is side view, the RD imaging algorithm is applied to process the echo signal to obtain the SAR wave synchronization data of a single view direction.
因为模拟包含多颗SAR的卫星组网，所以仿真获取多视向SAR海浪同步数 据。多颗SAR，可以是三颗、四颗、五颗或六颗等。Because the simulation includes multiple SAR satellite networks, the simulation obtains multi-view SAR wave synchronization data. Multiple SARs can be three, four, five, or six.
进一步地，基于多视向SAR海浪同步数据，运用MPI算法对各单星SAR海浪同步数据进行反演，得到各单星SAR海浪同步数据的最适海浪谱；具体步骤包括：Furthermore, based on the multi-view SAR wave synchronization data, the MPI algorithm is used to invert the single-satellite SAR wave synchronization data to obtain the optimal wave spectrum of the single-satellite SAR wave synchronization data; the specific steps include:
MPI算法描述了二维海浪谱到SAR图像谱的映射关系，通过初猜海浪谱，构造价值函数，通过迭代使价值函数最小化后，输出最适海浪谱和最适SAR谱。价值函数的定义为：The MPI algorithm describes the mapping relationship between the two-dimensional ocean wave spectrum and the SAR image spectrum. Through initial guessing of the ocean wave spectrum, the value function is constructed, and after the value function is minimized through iteration, the optimal ocean wave spectrum and the optimal SAR spectrum are output. The value function is defined as:
Figure PCTCN2019124305-appb-000012
Figure PCTCN2019124305-appb-000012
其中，
Figure PCTCN2019124305-appb-000013
是初猜海浪谱；F(k)是最适海浪谱；
Figure PCTCN2019124305-appb-000014
是观测SAR图像谱；P(k)是最适SAR图像谱；μ是反映初猜谱和观测SAR图像谱的相对置信区间的权重值；B是小正数，防止分母为零。 among them,
Figure PCTCN2019124305-appb-000013
It is the first guess of the wave spectrum; F(k) is the most suitable wave spectrum;
Figure PCTCN2019124305-appb-000014
Is the observed SAR image spectrum; P(k) is the most suitable SAR image spectrum; μ is the weight value reflecting the relative confidence interval of the initial guess spectrum and the observed SAR image spectrum; B is a small positive number to prevent the denominator from being zero.
MPI算法反演得到的部分结果图如图2(a)、图2(b)、图2(c)和图2(d)所示。该海浪数据的海浪传播方向是45°，海面10米高度处风速为10m/s，初猜谱为PM谱。The partial results obtained by the MPI algorithm inversion are shown in Figure 2(a), Figure 2(b), Figure 2(c) and Figure 2(d). The wave propagation direction of this wave data is 45°, the wind speed at 10 meters above sea level is 10m/s, and the initial guess spectrum is the PM spectrum.
多星海浪谱数据融合是截断波长补偿的基础。在进行数据融合之前，首先需要明确方位角(海浪传播方向与SAR方位向的夹角)与截断波长的关系，这是进行数据融合的依据。Multi-satellite wave spectrum data fusion is the basis of truncated wavelength compensation. Before data fusion, it is first necessary to clarify the relationship between the azimuth angle (the angle between the wave propagation direction and the SAR azimuth direction) and the cutoff wavelength, which is the basis for data fusion.
进一步地，估算各单星海浪数据的截断波长的公式：Further, the formula for estimating the cut-off wavelength of the wave data of each single star:
Figure PCTCN2019124305-appb-000015
Figure PCTCN2019124305-appb-000015
其中，
Figure PCTCN2019124305-appb-000016
among them,
Figure PCTCN2019124305-appb-000016
Figure PCTCN2019124305-appb-000017
Figure PCTCN2019124305-appb-000017
其中，β代表距离速度比，R是SAR平台到成像目标之间的斜距，V是SAR平台运行速度，
Figure PCTCN2019124305-appb-000018
是距离向速度调制传递函数，
Figure PCTCN2019124305-appb-000019
是频率，g＝9.81m/s 2是重力加速度，θ是SAR入射角，k r是波数矩阵k在距离向的分量，F(k)是海浪波数谱。k r和k满足如下关系： Among them, β represents the range-speed ratio, R is the slant distance between the SAR platform and the imaging target, and V is the operating speed of the SAR platform.
Figure PCTCN2019124305-appb-000018
Is the distance to velocity modulation transfer function,
Figure PCTCN2019124305-appb-000019
Is the frequency, g=9.81m/s 2 is the acceleration of gravity, θ is the SAR incident angle, k r is the component of the wavenumber matrix k in the distance direction, and F(k) is the wavenumber spectrum of the sea. k r and k satisfy the following relationship:
Figure PCTCN2019124305-appb-000020
Figure PCTCN2019124305-appb-000020
式中，
Figure PCTCN2019124305-appb-000021
是海浪传播方向与SAR距离向之间的夹角。 Where
Figure PCTCN2019124305-appb-000021
It is the angle between the wave propagation direction and the SAR range.
SAR海浪同步数据的方位角与截断波长值如表1所示。The azimuth angle and cutoff wavelength of the SAR wave synchronization data are shown in Table 1.
表1方位角及截断波长值Table 1 Azimuth angle and cutoff wavelength value
Figure PCTCN2019124305-appb-000022
Figure PCTCN2019124305-appb-000022
融合后的海浪谱估算的截断波长为195.072m，小于融合前的截断波长值，验证了提出的数据融合方法是有效的，实现了截断波长的补偿。The estimated cut-off wavelength of the wave spectrum after fusion is 195.072m, which is smaller than the cut-off wavelength value before fusion, which verifies that the proposed data fusion method is effective and realizes the compensation of the cut-off wavelength.
以上所述仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。The above descriptions are only preferred embodiments of the application, and are not used to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims (10)

  1. 多视向SAR海浪谱数据融合的海浪截断波长补偿方法，其特征是，包括：The wave truncation wavelength compensation method based on the fusion of multi-view SAR wave spectrum data is characterized by:
    进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫星的虚拟卫星组网，获得每颗SAR卫星的海浪同步数据；进而获得多视向SAR海浪同步数据；Carry out multi-directional SAR wave synchronization data simulation simulation, and obtain a virtual satellite network containing multiple SAR satellites, and obtain the wave synchronization data of each SAR satellite; and then obtain the multi-view SAR wave synchronization data;
    基于多视向SAR海浪同步数据，运用MPI算法对各单星SAR海浪同步数据进行反演，得到各单星SAR海浪同步数据的最适海浪谱，估算各单星海浪同步数据的截断波长；Based on the multi-directional SAR wave synchronization data, the MPI algorithm is used to invert the single-satellite SAR wave synchronization data to obtain the optimal wave spectrum of each single-satellite SAR wave synchronization data, and estimate the cut-off wavelength of each single-satellite wave synchronization data;
    根据方位角与截断波长的关系确定各单星SAR海浪同步数据的最适海浪谱的融合权值，根据各单星SAR海浪同步数据的最适海浪谱的融合权值对反演得到的最适海浪谱进行数据融合，融合之后得到多星融合之后的最适海浪谱；According to the relationship between the azimuth angle and the cut-off wavelength, the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data is determined. According to the optimal wave spectrum fusion weight of each single-satellite SAR wave synchronization data, the optimal value obtained by the inversion is Data fusion is performed on the wave spectrum, and the most suitable wave spectrum after multi-satellite fusion is obtained after fusion;
    基于多星融合之后的最适海浪谱，分别估算融合前后的最适海浪谱对应的截断波长，实现截断波长补偿。Based on the optimal wave spectrum after the multi-satellite fusion, the cut-off wavelength corresponding to the optimal wave spectrum before and after the fusion is estimated to realize the cut-off wavelength compensation.
  2. 如权利要求1所述的方法，其特征是，所述进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫星的虚拟卫星组网，获得每颗SAR卫星的海浪同步数据；进而获得多视向SAR海浪同步数据；具体步骤包括：The method according to claim 1, characterized in that the simulation of multi-view SAR wave synchronization data is performed, and a virtual satellite network including multiple SAR satellites is obtained through simulation, and the wave synchronization data of each SAR satellite is obtained; Obtain multi-directional SAR wave synchronization data; specific steps include:
    S11：进行多视向SAR海浪同步数据模拟仿真，仿真得到包含多颗SAR卫星的虚拟卫星组网；模拟生成海浪谱；基于模拟生成的海浪谱，模拟生成二维海面；S11: Carry out multi-view SAR wave synchronization data simulation simulation, and obtain a virtual satellite network containing multiple SAR satellites; simulate and generate a wave spectrum; based on the wave spectrum generated by the simulation, simulate a two-dimensional sea surface;
    S12：基于二维海面，计算海面电磁后向散射系数；S12: Based on the two-dimensional sea surface, calculate the sea surface electromagnetic backscattering coefficient;
    S13：基于海面电磁后向散射系数，生成二维海面的回波信号；S13: Generate a two-dimensional sea surface echo signal based on the sea surface electromagnetic backscattering coefficient;
    S14：对海面回波信号进行处理，得到多视向SAR海浪同步数据。S14: Process the sea surface echo signal to obtain multi-view SAR sea wave synchronization data.
  3. 如权利要求2所述的方法，其特征是，所述模拟生成海浪谱，是向二维PM波数方向谱输入波数、方向和风速，实现模拟生成海浪谱。The method according to claim 2, characterized in that the simulation to generate the ocean wave spectrum is to input the wave number, direction and wind speed to the two-dimensional PM wavenumber direction spectrum to realize the simulation to generate the ocean wave spectrum.
  4. 如权利要求3所述的方法，其特征是，所述采用二维PM波数方向谱实现模拟生成海浪谱；具体步骤如下：The method according to claim 3, wherein the two-dimensional PM wave number direction spectrum is used to realize the simulation and generation of the ocean wave spectrum; the specific steps are as follows:
    Figure PCTCN2019124305-appb-100001
    Figure PCTCN2019124305-appb-100001
    其中，a＝0.0081；b＝0.74；g 0为重力加速度，取9.81；K代表波数；U 19.5是海面19.5m高度处的风速；φ是海浪传播方向；φ m是主波波向，主波波向取值为风向角；φ-φ m代表的是海浪方向角，即海浪传播方向与风向的夹角，S PM(k,φ)表示模拟生成的海浪谱。 Among them, a = 0.0081; b = 0.74; g 0 is the acceleration of gravity, taking 9.81; K is the wave number; U 19.5 is the wind speed at the height of 19.5m on the sea surface; φ is the wave propagation direction; φ m is the main wave direction, the main wave The wave direction is taken as the wind direction angle; φ-φ m represents the wave direction angle, that is, the angle between the wave propagation direction and the wind direction. S PM (k, φ) represents the wave spectrum generated by the simulation.
  5. 如权利要求2所述的方法，其特征是，所述模拟生成二维海面，是向蒙特卡洛算法中输入二维PM波数方向谱，模拟生成二维海面。The method according to claim 2, wherein the simulation to generate a two-dimensional sea surface is to input a two-dimensional PM wave number direction spectrum into a Monte Carlo algorithm to simulate and generate a two-dimensional sea surface.
  6. 如权利要求2所述的方法，其特征是，所述模拟生成二维海面，具体步骤是：首先，生成二维高斯白噪声，其次，运用二维PM波数方向谱对白噪声进行线性滤波，得到海面高度起伏函数的傅里叶变换，对其做傅里叶逆变换即可得到二维海面。The method according to claim 2, wherein the simulation generates a two-dimensional sea surface, and the specific steps are: firstly, generate two-dimensional Gaussian white noise; secondly, use the two-dimensional PM wavenumber direction spectrum to linearly filter the white noise to obtain The Fourier transform of the sea level fluctuation function, and the inverse Fourier transform of it can get the two-dimensional sea surface.
  7. 如权利要求2所述的方法，其特征是，所述计算海面电磁后向散射系数，是选用双尺度电磁散射模型来进行计算。The method according to claim 2, wherein the calculation of the sea surface electromagnetic backscattering coefficient is performed by using a two-scale electromagnetic scattering model.
  8. 如权利要求2所述的方法，其特征是，所述生成二维海面的回波信号，是运用时域回波算法生成二维海面的回波信号。The method according to claim 2, wherein said generating the echo signal of the two-dimensional sea surface is to generate the echo signal of the two-dimensional sea surface using a time-domain echo algorithm.
  9. 如权利要求2所述的方法，其特征是，所述对海面回波信号进行处理，得到多视向SAR海浪同步数据；具体步骤为：The method according to claim 2, wherein said processing the sea surface echo signal to obtain multi-view SAR sea wave synchronization data; the specific steps are:
    在单颗SAR的工作模式为正侧视时，应用RD成像算法处理回波信号得到单个视向的SAR海浪同步数据；因为模拟包含多颗SAR的卫星组网，所以仿真获取多视向SAR海浪同步数据。When the working mode of a single SAR is side-view, the RD imaging algorithm is used to process the echo signal to obtain the SAR wave synchronization data of a single viewing direction; because the simulation contains multiple SAR satellite networks, the simulation obtains the multi-view SAR wave Synchronous Data.
  10. 如权利要求1所述的方法，其特征是，基于多视向SAR海浪同步数据，运用MPI算法对各单星SAR海浪同步数据进行反演，得到各单星SAR海浪同步数据的最适海浪谱；具体步骤包括：The method according to claim 1, characterized in that, based on the multi-view SAR wave synchronization data, the MPI algorithm is used to invert each single-satellite SAR wave synchronization data to obtain the optimal wave spectrum of each single-satellite SAR wave synchronization data ; The specific steps include:
    MPI算法描述了二维海浪谱到SAR图像谱的映射关系，通过初猜海浪谱，构造价值函数，通过迭代使价值函数最小化后，输出最适海浪谱和最适SAR谱。The MPI algorithm describes the mapping relationship between the two-dimensional ocean wave spectrum and the SAR image spectrum. Through initial guessing of the ocean wave spectrum, the value function is constructed, and after the value function is minimized through iteration, the optimal ocean wave spectrum and the optimal SAR spectrum are output.
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