CN-121978686-A - Multi-angle scattering characteristic spectrum measurement system and method for distributed formation SAR satellite group

CN121978686ACN 121978686 ACN121978686 ACN 121978686ACN-121978686-A

Abstract

The invention provides a multi-angle scattering characteristic spectrum measurement system and method for a distributed formation SAR satellite group, wherein the system comprises a satellite formation subsystem, a load cooperative observation subsystem, a signal processing subsystem and a spectrum construction subsystem, wherein the satellite formation subsystem is used for constructing an initial satellite formation and dynamically reconstructing, the load cooperative observation subsystem is used for cooperative observation of multiple satellites on the same area, the signal processing subsystem is used for realizing distributed holographic imaging processing of multi-satellite echo signals, and the spectrum construction subsystem is used for constructing a multi-dimensional space spectrum construction. According to the invention, through a concentric ring-spiral composite formation configuration and a real-time dynamic optimization algorithm, continuous full coverage of the three-dimensional attitude and the pitch angle of the ground target is realized, the highly coincident irradiation of multi-star radar beams to the same ground object area is ensured, and the scattering feature capturing bottleneck caused by the traditional formation angle dispersion is fundamentally broken through.

Inventors

LIU YANYANG
ZHANG YUN
KONG XIANGLONG
CHEN JUNLI
WEN JUNJIAN
ZHENG DANNI
CHEN ZHONGHUA

Assignees

上海卫星工程研究所

Dates

Publication Date: 20260505
Application Date: 20260106

Claims (10)

1. The distributed formation SAR satellite group multi-angle scattering characteristic spectrum measurement system is characterized by comprising a satellite formation subsystem, a load cooperative observation subsystem, a signal processing subsystem and a spectrum construction subsystem; the satellite formation subsystem is used for constructing an initial satellite formation and dynamically reconstructing; The load cooperative observation subsystem is used for cooperative observation of multiple satellites on the same area; the signal processing subsystem is used for realizing distributed holographic imaging processing of multi-star echo signals; the map construction subsystem is used for constructing a multidimensional space map construction.
2. The distributed formation SAR satellite group multi-angle scattering feature spectrum measurement system according to claim 1, wherein the satellite formation subsystem comprises concentric ring-spiral composite formation configurations formed by M transmitting satellites and N receiving satellites, wherein the concentric ring-spiral composite formation configurations are projected into concentric ring distribution on a vertical track plane, form a helix angle topology along the track direction, and are used for realizing continuous coverage of multiple azimuth angles and multiple pitch angles; The length of a formation base line of the satellite formation subsystem is dynamically adjustable, and the relative position of the satellite is adjusted in real time through an optimization algorithm so as to meet the constraint of the minimum safe distance and the stability condition of the orbit around the fly; the formation reconstruction mechanism of the satellite formation subsystem is used for autonomously switching configuration modes according to the requirements of observation tasks, and the configuration modes comprise an orbit-following baseline mode, an orbit-cutting baseline mode and a multi-baseline combined mode.
3. The distributed formation SAR satellite group multi-angle scattering feature map measurement system according to claim 1, wherein the T satellite in the load cooperative observation subsystem is equipped with a multi-band full-polarization SAR transmitter for signal code transmission and pulse repetition frequency adaptive adjustment; the R satellite in the load collaborative observation subsystem is provided with a multi-band full polarization DBF SAR receiver for digital beam forming and signal coherent synthesis; The load collaborative observation subsystem is characterized in that a time synchronization module, a phase synchronization module and a beam synchronization module are arranged between a T satellite and an R satellite, the time synchronization module is used for compensating carrier frequency phase noise, the phase synchronization module is used for correcting phase offset of a frequency source, and the beam synchronization module is used for carrying out collaborative control on the gesture of double satellites and electric wave beams so as to realize overlapping of double-satellite imaging areas.
4. The distributed formation SAR satellite group multi-angle scattering feature map measurement system according to claim 1, wherein the signal processing subsystem comprises an echo signal separation module for realizing echo separation corresponding to different transmission stars of the same reception star by using digital beam forming and signal coding technology; the signal processing subsystem comprises an imaging processing module and a processing module, wherein the imaging processing module is used for performing imaging processing on each echo data by utilizing a single/double-base imaging processing algorithm; the signal processing subsystem comprises a multi-angle sub-aperture dividing module which is used for dividing image data into sub-image sets according to azimuth angles and pitch angles and extracting pixel-level scattering characteristic parameters.
5. The system of claim 1, wherein the pattern constructing subsystem comprises a scattering feature extraction module for calculating a scattering direction and a scattering magnitude of each imaging unit, wherein the scattering direction is determined by radar observation geometry and external DEM positioning, the scattering magnitude is determined by the radiation corrected SAR image, and the scattering direction of each imaging unit is calculated Angle of coherence of scattering Amplitude of scattering , wherein, Wherein, the Indicating the angle A function of the scattering intensity of the direction, Representing the wavelength of the radar, Represents the equivalent pore size length and, The representation takes the magnitude of the complex number, Representing finding an argument that maximizes a function ; The map construction subsystem comprises a multidimensional space mapping module which is used for generating a multidimensional space map by fusing azimuth angle, pitch angle and polarization channel dimension information.
6. The multi-angle scattering characteristic spectrum measurement method for the distributed formation SAR satellite group is characterized by comprising the following steps of: step S1, satellite formation construction and dynamic reconstruction; S2, multi-star collaborative observation and synchronous control; step S3, processing the distributed holographic signals; and S4, constructing a multidimensional space map.
7. The method for measuring multi-angle scattering feature patterns of a distributed formation SAR satellite group according to claim 6, wherein said satellite formation construction and dynamic reconstruction comprises: S1.1, constructing a concentric ring-spiral composite formation configuration, wherein vertical track surface projections are distributed in concentric rings, and form a spiral angle topology along the track direction, and the radius and the spiral angle of the concentric rings are dynamically adjusted according to the rotation compensation requirement of the earth; Step S1.2, independently switching a track following baseline, a track cutting baseline or a multi-baseline combination mode according to task requirements; step S1.3, optimizing the formation baseline length in real time based on an optimization algorithm, and measuring errors The following constraints are satisfied: Wherein, the The satellite position vector is represented by a vector of satellite positions, The satellite is given a number that is the number, Indicating the minimum allowable distance to be used for the device, Indicating the maximum allowable distance to be used, The fuel consumption amount is indicated as a result of the fuel consumption, Indicating an upper fuel consumption limit.
8. The method for measuring the multi-angle scattering feature map of the distributed formation SAR satellite group according to claim 6, wherein said multi-star cooperative observation and synchronization control comprises: S2.1, transmitting a multi-band full-polarization SAR signal by a T satellite, and acquiring an echo by an R satellite through a full-polarization DBF receiver; S2.2, realizing time synchronization by adopting a bidirectional pulse transmission protocol, and realizing phase synchronization by adopting a radar and GNSS common frequency source design; and S2.3, adjusting a beam pointing angle based on imaging region overlapping rate feedback, and ensuring the overlapping degree of the double star beam coverage areas.
9. The method for measuring the multi-angle scattering feature map of the distributed formation SAR satellite group according to claim 6, wherein said distributed holographic signal processing comprises: step S3.1 mapping the matrix by phase center Calculating, namely mapping the non-uniformly distributed receiving satellite positions into a virtual equidistant phase center array by adopting bistatic range migration correction, wherein, Wherein, the Representing virtual equally spaced phase center coordinates, Representing the actual satellite position coordinates, Representing a phase center mapping matrix; and S3.2, dividing the full-aperture data into sub-image sets according to azimuth angles and pitch angles, and extracting pixel-level scattering characteristic parameters.
10. The method for measuring the multi-angle scattering feature map of the distributed formation SAR satellite group according to claim 6, wherein said multi-dimensional space map construction comprises: step S4.1, calculating the scattering direction and the scattering amplitude of each imaging unit, wherein the scattering direction is determined by radar observation geometry and external DEM positioning, the scattering amplitude is determined by SAR images after radiation correction, and the scattering direction of each imaging unit is calculated Angle of coherence of scattering Amplitude of scattering , wherein, Wherein, the Indicating the angle A function of the scattering intensity of the direction, Representing the wavelength of the radar, Represents the equivalent pore size length and, The representation takes the magnitude of the complex number, Representing finding an argument that maximizes a function ; And S4.2, generating a multidimensional space map by fusing azimuth angle, pitch angle and polarization channel dimension information.

Description

Multi-angle scattering characteristic spectrum measurement system and method for distributed formation SAR satellite group Technical Field The invention relates to the technical field of satellite-borne radar system design and signal processing, in particular to a distributed formation SAR satellite group multi-angle scattering characteristic spectrum measurement system and method. Background The space-borne Synthetic Aperture Radar (SAR) is an active microwave imaging sensor taking a satellite as a platform, and realizes distance-oriented high-resolution imaging by transmitting broadband frequency modulation signals and a pulse compression technology, and realizes azimuth-oriented high-resolution imaging by an azimuth virtual synthetic aperture technology. The spaceborne SAR image contains rich geometric, radiation and phase information, is a main technical means for all-weather earth observation in all weather, and has important significance for resource exploration, environment monitoring and military reconnaissance in the acquired electromagnetic scattering information. However, the traditional SAR imaging mode has the remarkable limitations that a single star or fixed formation system is limited by the single observation view angle, only can capture scattering response under discrete angles, cannot continuously cover the global scattering characteristic of a target in a three-dimensional space, and meanwhile, the traditional SAR system cannot construct the space scattering characteristic map of the target due to the lack of multi-dimensional physical parameter synchronous extraction capability and insufficient inter-star synchronous precision. Therefore, the research realizes the omnibearing sensing of the target space scattering characteristic, and the construction of the multi-angle scattering characteristic space spectrum technology is important to the improvement of the SAR system performance. Document "First Bistatic Spaceborne SAR Experiments With TanDEM-X"（Rodriguez-Cassola, M. et al. IEEE geoscience and remote sensing letters 9.1 (2012): 33–37. Print.） verifies the visual angle limitation of the traditional SAR system through double-star experiments that the fixed formation configuration leads to discrete sampling of the target scattering response, and the three-dimensional space continuous coverage cannot be realized. In the experiment, even if only a tiny double-base angle exists between satellites, the scattering characteristics of the artificial building are obviously different, and the scattering evolution process under the continuous change of the azimuth angle is proved to be influenced. In the vertical dimension, short baseline constraints severely limit pitch coverage. This result demonstrates that the discrete sampling mode of the fixed queuing system restricts the continuous perceptibility of the global scattering properties of the target space. The literature (Song Wei, dan Meng, yang Yang. Mapping report, 2025 (1): 78-82. DOI:10.13474/j. Cnki.11-2246.2025.0113.) proposes a water information extraction method based on full-polarization single-base SAR high-frequency three (GF-3) image, two water index features are constructed by analyzing scattering characteristic differences of different polarization modes (HH, HV, VH, VV), and the two water index features are combined into a new feature image, and the rapid high-precision water extraction is realized by combining an object-oriented classification technology. The method has the advantages that complementarity of full polarization data is fully excavated, distinguishing capability of water bodies and non-water bodies is remarkably improved, the problem that the water bodies in the single polarization SAR are mixed with similar scattering ground features is effectively solved, but space information (such as terrain association features) of azimuth angles and pitch angles is not explicitly utilized, and monitoring potential of multi-time phase polarization features on dynamic water bodies is not further explored. Document (Xu Xinyu. Seisan electronic technology university, 2024.DOI: 10.27389/d.cnki.gxadu.2024.000370.) proposes a polarized SAR target detection framework integrating a physical scattering mechanism with deep learning, wherein a super-pixel segmentation method is adopted to perform pre-detection and false alarm suppression by extracting polarization related features of a rotation domain, and two stages are combined with unsupervised anomaly detection and polarization scattering features to complete target positioning, so that multi-scale features are extracted by utilizing the polarization mode of the rotation domain to enhance target separability, and the false alarm rate is reduced in an unsupervised network by integrating polarization feature prior. According to the method, a single-base backscattering model is adopted to extract azimuth angle information to construct rotation invariant features, HH/VV homopolar channe