CN112558070B - Frequency domain imaging method and device of circular scanning foundation SAR - Google Patents

Frequency domain imaging method and device of circular scanning foundation SAR Download PDF

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CN112558070B
CN112558070B CN202110190842.8A CN202110190842A CN112558070B CN 112558070 B CN112558070 B CN 112558070B CN 202110190842 A CN202110190842 A CN 202110190842A CN 112558070 B CN112558070 B CN 112558070B
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林赟
冯子龙
王彦平
李洋
申文杰
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North China University of Technology
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    • 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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    • 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
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    • 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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    • G01S13/9011—SAR image acquisition techniques with frequency domain processing of the SAR signals in azimuth
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    • 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
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    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
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Abstract

The invention discloses a frequency domain imaging method and a frequency domain imaging device of a circular scanning foundation SAR, wherein the method comprises the following steps: carrying out distance inverse Fourier transform on the echo signals of the circular scanning foundation SAR to obtain distance compression time domain signals; resampling the distance compressed time domain signal according to a preset first distance sampling interval and a geometrical corresponding relation; carrying out distance direction Fourier transform and azimuth direction Fourier transform to obtain a distance frequency domain and azimuth direction frequency domain signal; carrying out azimuth matching filtering on the distance frequency domain azimuth frequency domain signal according to a pre-constructed matching filtering function to obtain a signal after matching filtering; performing two-dimensional inverse Fourier transform on the matched and filtered signals to obtain a focused image under a polar coordinate system; the method and the device can improve the imaging efficiency while ensuring the imaging quality and realize rapid real-time imaging.

Description

圆周扫描地基SAR的频域成像方法及装置Frequency Domain Imaging Method and Device for Circular Scanning Ground-based SAR

技术领域technical field

本发明涉及地基SAR三维成像技术领域，尤其涉及圆周扫描地基SAR的频域成像方法及装置。The invention relates to the technical field of ground-based SAR three-dimensional imaging, in particular to a frequency domain imaging method and device of a circular scanning ground-based SAR.

背景技术Background technique

近年来，地基合成孔径雷达（Ground-based Synthetic Aperture Radar，GBSAR）广泛应用于滑坡监测、火山监测、冰川监测、露天矿场监测、桥梁和建筑物监测等领域。但是传统的直线轨道（GBSAR）只能获取二维图像，在地形起伏区域存在“叠掩”问题，不适用于复杂地形，且不能获取监测场景的三维地形信息。In recent years, Ground-based Synthetic Aperture Radar (GBSAR) has been widely used in landslide monitoring, volcano monitoring, glacier monitoring, open-pit mine monitoring, bridge and building monitoring and other fields. However, the traditional linear orbit (GBSAR) can only obtain two-dimensional images, and there is a "overlapping" problem in the terrain relief area, which is not suitable for complex terrain, and cannot obtain the three-dimensional terrain information of the monitoring scene.

圆周扫描地基SAR是一种具有三维成像能力的新体制地基SAR。与传统的直线轨道地基SAR相比，圆周扫描地基SAR天线通过悬臂旋转形成垂直于地面的圆形轨迹，从而形成二维合成孔径，获取高度向信息，以实现三维成像。因此，它具有系统结构便捷，数据采集快，滑坡监测时效性强的优势。Circular scanning ground-based SAR is a new system of ground-based SAR with three-dimensional imaging capability. Compared with the traditional linear orbit ground-based SAR, the circular scanning ground-based SAR antenna forms a circular trajectory perpendicular to the ground through the rotation of the cantilever, thereby forming a two-dimensional synthetic aperture and obtaining height information to realize three-dimensional imaging. Therefore, it has the advantages of convenient system structure, fast data collection, and strong timeliness of landslide monitoring.

圆周扫描地基SAR成像的难点在于天线运动轨迹是弧线。由于运动轨迹特殊，以往的频域成像方法不适用于圆周扫描地基SAR。机载的圆周SAR通过向航迹内侧发射信号进行成像；悬臂扫描（ArcSAR）平行于地面，通过向外侧发射信号进行成像。而圆周扫描地基SAR垂直于地面，向前方发射信号，与它们的成像模式不同。时域成像方法虽然适用于圆周扫描地基SAR系统并能够得到高精度成像结果，但时域成像方法计算量大，成像效率低，很难实现快速实时成像。The difficulty of circular scanning ground-based SAR imaging is that the trajectory of the antenna is an arc. Due to the special motion trajectory, the previous frequency domain imaging methods are not suitable for circular scanning ground-based SAR. The airborne circular SAR performs imaging by transmitting signals to the inner side of the track; the cantilever scanning (ArcSAR) is parallel to the ground and imaging by transmitting signals to the outer side. Circumferential scanning ground-based SARs, on the other hand, are perpendicular to the ground and transmit signals forward, unlike their imaging modes. Although the time-domain imaging method is suitable for the circular scanning ground-based SAR system and can obtain high-precision imaging results, the time-domain imaging method has a large amount of calculation and low imaging efficiency, and it is difficult to achieve fast real-time imaging.

因此，亟需一种可以克服上述问题的圆周扫描地基SAR的频域成像方案。Therefore, there is an urgent need for a frequency-domain imaging solution for circular scanning ground-based SAR that can overcome the above problems.

发明内容SUMMARY OF THE INVENTION

本发明实施例提供一种圆周扫描地基SAR的频域成像方法，用以进行圆周扫描地基SAR的频域成像，在保证成像质量的同时提高成像效率，实现快速实时成像，该方法包括：An embodiment of the present invention provides a frequency domain imaging method for a circular scanning ground-based SAR, which is used to perform frequency domain imaging of a circular scanning ground-based SAR, improves imaging efficiency while ensuring imaging quality, and realizes fast real-time imaging. The method includes:

获得圆周扫描地基SAR的回波信号；Obtain the echo signal of the circular scanning ground-based SAR;

对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；Perform range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain a range compressed time domain signal;

根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；resampling the distance-compressed time-domain signal according to the preset first distance sampling interval and geometric correspondence;

对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；Perform range Fourier transform and azimuth Fourier transform on the resampled range-compressed time-domain signal to obtain the range-frequency-domain azimuth-frequency-domain signal;

根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；Perform azimuth matched filtering on the range-frequency-domain, azimuth-frequency-domain signal according to a pre-configured matched filter function to obtain a matched-filtered signal, and the matched filter function is pre-configured according to a conjugate algorithm;

对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；Perform a two-dimensional inverse Fourier transform on the matched filtered signal to obtain a focused image in the polar coordinate system;

对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；Perform interpolation processing on the focused image in the polar coordinate system to obtain the focused image in the rectangular coordinate system;

根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。According to the focused image in the rectangular coordinate system, the frequency domain imaging of the circular scanning ground-based SAR is performed.

本发明实施例提供一种圆周扫描地基SAR的频域成像装置，用以进行圆周扫描地基SAR的频域成像，在保证成像质量的同时提高成像效率，实现快速实时成像，该装置包括：An embodiment of the present invention provides a frequency domain imaging device for circular scanning ground-based SAR, which is used for frequency domain imaging of circular scanning ground-based SAR, improves imaging efficiency while ensuring imaging quality, and realizes fast real-time imaging. The device includes:

回波信号获得模块，用于获得圆周扫描地基SAR的回波信号；The echo signal acquisition module is used to obtain the echo signal of the circular scanning ground-based SAR;

第一变换模块，用于对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；The first transformation module is used to perform range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain a range-compressed time-domain signal;

重采样模块，用于根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；a resampling module for resampling the distance-compressed time-domain signal according to a preset first distance sampling interval and a geometric correspondence;

第二变换模块，用于对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；The second transformation module is used to perform range-to-Fourier transform and azimuth-to-Fourier transform on the resampled range-compressed time-domain signal to obtain a range-frequency-domain azimuth-frequency-domain signal;

匹配滤波模块，用于根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；a matched filter module, configured to perform azimuth matched filtering on the distance-frequency-domain, azimuth-frequency-domain signal according to a pre-configured matched filter function, and obtain a matched-filtered signal, and the matched filter function is pre-configured according to a conjugate algorithm;

第三变换模块，用于对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；The third transformation module is used to perform two-dimensional inverse Fourier transformation on the matched filtered signal to obtain a focused image in the polar coordinate system;

插值处理模块，用于对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；an interpolation processing module for performing interpolation processing on the focused image in the polar coordinate system to obtain the focused image in the rectangular coordinate system;

频域成像模块，用于根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。The frequency domain imaging module is used to perform frequency domain imaging of the circular scanning ground-based SAR according to the focused image in the rectangular coordinate system.

本发明实施例还提供一种计算机设备，包括存储器、处理器及存储在存储器上并可在处理器上运行的计算机程序，所述处理器执行所述圆周扫描地基SAR的频域成像方法。An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the frequency domain imaging method of the circular scanning ground-based SAR.

本发明实施例还提供一种计算机可读存储介质，所述计算机可读存储介质存储有执行上述圆周扫描地基SAR的频域成像方法的计算机程序。An embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program for executing the above-mentioned frequency domain imaging method of the circular scanning ground-based SAR.

本发明实施例通过获得圆周扫描地基SAR的回波信号； 对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。本发明实施例通过重采样将回波信号从斜平面转换到成像平面，信号数据的转换，还通过傅里叶变换在频域进行目标的聚焦，计算效率高，成像速度快，方便进行实时成像，从而在保证成像质量的同时提高成像效率，实现场景的快速实时成像。In the embodiment of the present invention, the echo signal of the circular scanning ground-based SAR is obtained; the range-inverse Fourier transform is performed on the echo signal of the circular scanning ground-based SAR to obtain a range-compressed time-domain signal; according to a preset first distance The sampling interval and the geometric correspondence are used to resample the range-compressed time-domain signal; the range-to-Fourier transform and the azimuth-to-Fourier transform are performed on the resampled range-compressed time-domain signal to obtain the range-frequency-domain azimuth-frequency signal. domain signal; perform azimuth matched filtering on the distance-frequency-domain azimuth-frequency-domain signal according to a pre-constructed matched filter function to obtain a matched-filtered signal, and the matched-filter function is pre-constructed according to a conjugate algorithm; The signal is subjected to two-dimensional inverse Fourier transform to obtain a focused image in the polar coordinate system; interpolation processing is performed on the focused image in the polar coordinate system to obtain a focused image in the rectangular coordinate system; according to the focused image in the rectangular coordinate system, the Frequency Domain Imaging of Circular Scanning Ground-Based SAR. In the embodiment of the present invention, the echo signal is converted from the oblique plane to the imaging plane by resampling, the signal data is converted, and the target is focused in the frequency domain through Fourier transform, the calculation efficiency is high, the imaging speed is fast, and real-time imaging is convenient. , so as to improve the imaging efficiency while ensuring the imaging quality, and realize the fast real-time imaging of the scene.

附图说明Description of drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。在附图中：In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts. In the attached image:

图1为本发明实施例中圆周扫描地基SAR的频域成像方法示意图；Fig. 1 is the schematic diagram of the frequency domain imaging method of the circular scanning ground-based SAR in the embodiment of the present invention;

图2为本发明实施例中圆周扫描地基SAR成像模式的成像几何示意图；Fig. 2 is the imaging geometry schematic diagram of the circular scanning ground-based SAR imaging mode in the embodiment of the present invention;

图3为本发明实施例中成像平面几何模型示意图；3 is a schematic diagram of an imaging plane geometric model in an embodiment of the present invention;

图4为本发明实施例中圆周扫描地基SAR的频域成像装置结构图。FIG. 4 is a structural diagram of a frequency domain imaging device of a circular scanning ground-based SAR in an embodiment of the present invention.

具体实施方式Detailed ways

为使本发明实施例的目的、技术方案和优点更加清楚明白，下面结合附图对本发明实施例做进一步详细说明。在此，本发明的示意性实施例及其说明用于解释本发明，但并不作为对本发明的限定。In order to make the purposes, technical solutions and advantages of the embodiments of the present invention more clearly understood, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

为了进行圆周扫描地基SAR的频域成像，在保证成像质量的同时提高成像效率，实现快速实时成像，本发明实施例提供一种圆周扫描地基SAR的频域成像方法，如图1所示，该方法可以包括：In order to perform frequency domain imaging of circular scanning ground-based SAR, improve imaging efficiency while ensuring imaging quality, and achieve fast real-time imaging, an embodiment of the present invention provides a frequency domain imaging method for circular scanning ground-based SAR, as shown in FIG. 1 , the Methods can include:

步骤101、获得圆周扫描地基SAR的回波信号；Step 101, obtain the echo signal of the circular scanning ground-based SAR;

步骤102、对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；Step 102, performing a range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain a range-compressed time-domain signal;

步骤103、根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；Step 103, resampling the distance-compressed time-domain signal according to the preset first distance sampling interval and geometric correspondence;

步骤104、对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；Step 104, performing a range-direction Fourier transform and an azimuth-direction Fourier transform on the resampled range-compressed time-domain signal to obtain a range-frequency-domain, azimuth-frequency-domain signal;

步骤105、根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；Step 105, performing azimuth matched filtering on the distance-frequency-domain azimuth-frequency-domain signal according to a pre-configured matched filter function, to obtain a matched-filtered signal, and the matched-filter function is pre-configured according to a conjugate algorithm;

步骤106、对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；Step 106, performing a two-dimensional inverse Fourier transform on the matched filtered signal to obtain a focused image in a polar coordinate system;

步骤107、对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；Step 107, performing interpolation processing on the focused image in the polar coordinate system to obtain a focused image in the rectangular coordinate system;

步骤108、根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。Step 108: Perform frequency domain imaging of the circular scanning ground-based SAR according to the focused image in the Cartesian coordinate system.

由图1所示可以得知，本发明实施例通过获得圆周扫描地基SAR的回波信号； 对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。本发明实施例通过重采样将回波信号从斜平面转换到成像平面，信号数据的转换，还通过傅里叶变换在频域进行目标的聚焦，计算效率高，成像速度快，方便进行实时成像，从而在保证成像质量的同时提高成像效率，实现场景的快速实时成像。As shown in FIG. 1, it can be known that the embodiment of the present invention obtains the echo signal of the circular scanning ground-based SAR; performs the range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain the range-compressed time-domain signal ; According to the preset first distance sampling interval and geometric correspondence, re-sampling the distance-compressed time-domain signal; Carry out the range-direction Fourier transform and the azimuth-direction Fourier transform on the resampled distance-compressed time-domain signal Leaf transform to obtain a range frequency domain azimuth frequency domain signal; perform azimuth matched filtering on the range frequency domain azimuth frequency domain signal according to a pre-constructed matched filter function to obtain a matched filtered signal, and the matched filter function is based on the conjugate The algorithm is pre-constructed; the two-dimensional inverse Fourier transform is performed on the matched filtered signal to obtain the focused image in the polar coordinate system; the focused image in the polar coordinate system is interpolated to obtain the focused image in the rectangular coordinate system; The image is focused in the rectangular coordinate system, and the frequency domain imaging of the circular scanning ground-based SAR is performed. In the embodiment of the present invention, the echo signal is converted from the oblique plane to the imaging plane by resampling, the signal data is converted, and the target is focused in the frequency domain through Fourier transform, the calculation efficiency is high, the imaging speed is fast, and real-time imaging is convenient. , so as to improve the imaging efficiency while ensuring the imaging quality, and realize the fast real-time imaging of the scene.

圆周扫描地基SAR系统成像的难点在于天线运动轨迹为垂直于地面的弧线，向前方扫描观测来进行大范围成像，特殊的运动轨迹增加了成像的难度。现已有成像方法为后向投影（BP）方法，该方法将成像区域划分为网格点，并按照每个网格点与天线的回波时延来确定其像素值，再将天线360°采集的像素值进行相干叠加，从而实现成像。虽然成像精度较高，但计算量巨大，成像效率低，难以实现快速实时成像。The difficulty in the imaging of the circular scanning ground-based SAR system is that the trajectory of the antenna is an arc perpendicular to the ground, and it scans and observes forward to perform large-scale imaging. The special trajectory increases the difficulty of imaging. The existing imaging method is the back projection (BP) method, which divides the imaging area into grid points, and determines its pixel value according to the echo delay between each grid point and the antenna, and then divides the antenna 360°. The acquired pixel values are coherently superimposed to achieve imaging. Although the imaging accuracy is high, the computational complexity is huge and the imaging efficiency is low, making it difficult to achieve fast real-time imaging.

图2为圆周扫描地基SAR成像模式的成像几何，图3为成像平面几何模型，即图2的侧视图。a为雷达相位中心，天线通过悬臂Oa沿着水平中轴旋转，形成以O为旋转中心的圆形运动轨迹，对前方场景进行圆周扫描，X-Y-Z为直角坐标系，悬臂长度（即轨迹半径）为L，相位中心旋转角度为

Figure 913525DEST_PATH_IMAGE001
，即系统的方位向。P为预设点目标，在如图2所示的平面Z p 上。点目标所在平面与天线运动轨迹的垂直距离为Z p 。点目标与相位中心的瞬时斜距为R n ，即系统的距离向。本发明实施例将天线运动轨迹投影到点目标所在二维平面，如图3所示。点目标与相位中心投影a的瞬时距离为r gp ，则每一个瞬时斜距R n 都对应着成像平面的一个瞬时距离r gp ，按照这种对应关系即可完成斜平面回波信号数据与成像平面信号数据的转换，从而实现点目标所在平面Z p 的二维成像。改变不同的Z p 即可完成不同距离平面的二维成像，从而实现场景的三维成像。FIG. 2 is the imaging geometry of the circular scanning ground-based SAR imaging mode, and FIG. 3 is the imaging plane geometry model, that is, the side view of FIG. 2 . a is the radar phase center, the antenna rotates along the horizontal axis through the cantilever Oa , forming a circular motion trajectory with O as the rotation center, and performs a circular scan on the front scene, XYZ is a Cartesian coordinate system, and the cantilever length (that is, the trajectory radius) is L , the phase center rotation angle is
Figure 913525DEST_PATH_IMAGE001
, the azimuth of the system. P is the preset point target, which is on the plane Z p as shown in FIG. 2 . The vertical distance between the plane where the point target is located and the trajectory of the antenna is Z p . The instantaneous slope distance between the point target and the phase center is R n , that is, the distance direction of the system. In the embodiment of the present invention, the motion trajectory of the antenna is projected onto the two-dimensional plane where the point target is located, as shown in FIG. 3 . The instantaneous distance between the point target and the phase center projection a is r gp , then each instantaneous slant distance R n corresponds to an instantaneous distance r gp of the imaging plane, and the slant plane echo signal data and imaging can be completed according to this correspondence The transformation of the plane signal data, so as to realize the two-dimensional imaging of the plane Z p where the point target is located. Two-dimensional imaging of different distance planes can be completed by changing different Z p , thereby realizing three-dimensional imaging of the scene.

实施例中，获得圆周扫描地基SAR的回波信号。In the embodiment, the echo signal of the circular scanning ground-based SAR is obtained.

具体实施时，设相位中心的空间位置坐标为（x n ，y n ，z n ），其中In specific implementation, the spatial position coordinates of the phase center are set as ( x n , y n , z n ), where

Figure 909294DEST_PATH_IMAGE002
Figure 909294DEST_PATH_IMAGE002

其中，

Figure 220189DEST_PATH_IMAGE003
为相位中心旋转的角度，L为相位中心的旋转半径。点目标P的空间位置坐标为（x n ，y n ，z n ），点目标与相位中心的瞬时斜距R n 可以表示为：in,
Figure 220189DEST_PATH_IMAGE003
is the rotation angle of the phase center, and L is the rotation radius of the phase center. The spatial position coordinates of the point target P are ( x n , yn , z n ), and the instantaneous slope distance R n between the point target and the phase center can be expressed as:

Figure 146557DEST_PATH_IMAGE004
Figure 146557DEST_PATH_IMAGE004

设K为斜平面距离向波数，可以表示为：Let K be the oblique plane distance wavenumber, which can be expressed as:

Figure 695350DEST_PATH_IMAGE005
Figure 695350DEST_PATH_IMAGE005

其中f为信号频率，c为光速。where f is the signal frequency and c is the speed of light.

圆周扫描地基SAR回波信号定义为

Figure 799703DEST_PATH_IMAGE006
，表示为：The circular scanning ground-based SAR echo signal is defined as
Figure 799703DEST_PATH_IMAGE006
,Expressed as:

Figure 863474DEST_PATH_IMAGE007
。
Figure 863474DEST_PATH_IMAGE007
.

实施例中，对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号。In the embodiment, the range-inverse Fourier transform is performed on the echo signal of the circular scanning ground-based SAR to obtain a range-compressed time-domain signal.

具体实施时，圆周扫描地基SAR的回波信号经过距离向逆傅里叶变换（IFT）后转换到了距离压缩时域信号，表示为

Figure 796795DEST_PATH_IMAGE008
：In the specific implementation, the echo signal of the circular scanning ground-based SAR is converted into a range-compressed time-domain signal after inverse range Fourier transform (IFT), which is expressed as
Figure 796795DEST_PATH_IMAGE008
:

Figure 793570DEST_PATH_IMAGE009
Figure 793570DEST_PATH_IMAGE009

其中，r代表点目标到雷达相位中心的距离，B r 是信号带宽，K c 是中心波数。Among them, r represents the distance from the point target to the radar phase center, B r is the signal bandwidth, and K c is the center wave number.

实施例中，根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样。In an embodiment, the distance-compressed time-domain signal is resampled according to a preset first distance sampling interval and a geometric correspondence.

本实施例中，所述几何对应关系根据点目标到雷达在平面上的投影距离，点目标到雷达相位中心的距离和点目标所在平面与天线运动轨迹的垂直距离预先设定。In this embodiment, the geometric correspondence is preset according to the projected distance from the point target to the radar on the plane, the distance from the point target to the phase center of the radar, and the vertical distance between the plane where the point target is located and the trajectory of the antenna.

具体实施时，所述几何对应关系为：During specific implementation, the geometric correspondence is:

Figure 65895DEST_PATH_IMAGE010
Figure 65895DEST_PATH_IMAGE010

本实施例中，所述第一距离采样间隔根据点目标到雷达相位中心的距离所对应的最大波数，点目标到雷达在平面上的投影距离所对应的最大波数，以及波束入射角预先设定。In this embodiment, the first distance sampling interval is preset according to the maximum wave number corresponding to the distance from the point target to the radar phase center, the maximum wave number corresponding to the projection distance from the point target to the radar on the plane, and the beam incident angle .

具体实施时，对距离压缩时域信号进行重采样，实现回波数据由斜平面到成像平面的转换。该过程通过一维插值实现，通过几何对应关系可以将

Figure 882541DEST_PATH_IMAGE011
重采样为。
Figure 353974DEST_PATH_IMAGE012
插值时原斜距R n 可以重写为：During specific implementation, the range-compressed time-domain signal is resampled to realize the conversion of echo data from the oblique plane to the imaging plane. This process is realized by one-dimensional interpolation, and the geometric correspondence can be used to convert
Figure 882541DEST_PATH_IMAGE011
Resampled to.
Figure 353974DEST_PATH_IMAGE012
The original slope distance R n during interpolation can be rewritten as:

Figure 408518DEST_PATH_IMAGE013
Figure 408518DEST_PATH_IMAGE013

其中，r g 为点目标到雷达在z p 平面上投影的距离。将

Figure 385832DEST_PATH_IMAGE014
乘以相移函数从而将时域信号移到正确的位置，得到重采样后的距离压缩时域信号：Among them, r g is the distance from the point target to the radar projection on the z p plane. Will
Figure 385832DEST_PATH_IMAGE014
Multiply by the phase-shift function to move the time-domain signal to the correct position, and get the resampled range-compressed time-domain signal:

Figure 158616DEST_PATH_IMAGE015
Figure 158616DEST_PATH_IMAGE015

其中，B rg 为成像平面对应的带宽，r gp 为点目标与相位中心投影的瞬时距离。成像平面对应的带宽为：Among them, B rg is the bandwidth corresponding to the imaging plane, and r gp is the instantaneous distance between the point target and the phase center projection. The corresponding bandwidth of the imaging plane is:

Figure 964898DEST_PATH_IMAGE016
Figure 964898DEST_PATH_IMAGE016

其中，

Figure 139527DEST_PATH_IMAGE017
为波束入射角，随着相位中心的旋转而不断变化，但是由于圆周扫描地基SAR的旋转半径L远小于雷达的探测距离，相位中心在不同旋转角度引起的
Figure 756585DEST_PATH_IMAGE017
的变化可以忽略不计，实际数据处理时，将
Figure 16665DEST_PATH_IMAGE017
视为旋转中心O到成像区域的夹角。如图3中，设成像区域半径为in,
Figure 139527DEST_PATH_IMAGE017
is the beam incidence angle, which changes continuously with the rotation of the phase center. However, because the rotation radius L of the circular scanning ground-based SAR is much smaller than the detection distance of the radar, the phase center is caused by different rotation angles.
Figure 756585DEST_PATH_IMAGE017
The change is negligible, the actual data processing, will
Figure 16665DEST_PATH_IMAGE017
It is regarded as the angle between the rotation center O and the imaging area. As shown in Figure 3, the radius of the imaging area is set as

Figure 829900DEST_PATH_IMAGE018
Figure 829900DEST_PATH_IMAGE018

其中，X 1代表人为设定的z p 平面上的成像区域半径，则：Among them, X 1 represents the radius of the imaging area on the artificially set z p plane, then:

Figure 859036DEST_PATH_IMAGE019
Figure 859036DEST_PATH_IMAGE019

那么，由以上得到：Then, from the above we get:

Figure 161841DEST_PATH_IMAGE020
Figure 161841DEST_PATH_IMAGE020

其中，K max和K gmax为分别与r和r g 对应的最大波数。Among them, K max and K g max are the maximum wave numbers corresponding to r and r g respectively.

因此，在插值的网格设定时，成像平面的距离采样间隔d rg 需满足如下公式：Therefore, when the interpolation grid is set, the distance sampling interval d rg of the imaging plane must satisfy the following formula:

Figure 659950DEST_PATH_IMAGE021
。
Figure 659950DEST_PATH_IMAGE021
.

实施例中，对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号。In the embodiment, the range-direction Fourier transform and the azimuth-direction Fourier transform are performed on the resampled range-compressed time-domain signal to obtain the range-frequency-domain azimuth-frequency-domain signal.

具体实施时，重采样完成后对

Figure 276876DEST_PATH_IMAGE022
作距离向傅里叶变换（FT），得到距离频域-方位时域信号
Figure 160518DEST_PATH_IMAGE023
：In specific implementation, after the resampling is completed, the
Figure 276876DEST_PATH_IMAGE022
Perform range to Fourier transform (FT) to obtain range frequency domain-azimuth time domain signal
Figure 160518DEST_PATH_IMAGE023
:

Figure 899804DEST_PATH_IMAGE024
Figure 899804DEST_PATH_IMAGE024

其中，K g 为与r g 对应的成像平面的波数，点目标与相位中心投影的瞬时距离为

Figure 868897DEST_PATH_IMAGE025
。Among them, K g is the wave number of the imaging plane corresponding to r g , and the instantaneous distance between the point target and the phase center projection is
Figure 868897DEST_PATH_IMAGE025
.

实施例中，根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造。In an embodiment, azimuth and direction matched filtering is performed on the range frequency domain and azimuth frequency domain signals according to a pre-configured matched filter function, and a matched filtered signal is obtained, and the matched filter function is pre-configured according to a conjugate algorithm.

具体实施时，r gp 随着相位中心旋转角度

Figure 23935DEST_PATH_IMAGE026
存在近似正弦的波动。R 0为点目标P到轨迹中心O的距离。根据余弦定理可知：In specific implementation, r gp rotates with the phase center
Figure 23935DEST_PATH_IMAGE026
There are approximately sinusoidal fluctuations. R 0 is the distance from the point target P to the trajectory center O. According to the cosine law:

Figure 775466DEST_PATH_IMAGE027
Figure 775466DEST_PATH_IMAGE027

其中，L为雷达旋转轨迹半径，L= R 0，因此在数据处理时将r gp 取近似为：

Figure 685653DEST_PATH_IMAGE028
Among them, L is the radius of radar rotation trajectory, L = R 0 , so r gp is approximated as:
Figure 685653DEST_PATH_IMAGE028

近似前后引起的相位误差不能超过

Figure 142042DEST_PATH_IMAGE029
，对应到距离误差
Figure 897509DEST_PATH_IMAGE030
即为：The phase error caused before and after the approximation cannot exceed
Figure 142042DEST_PATH_IMAGE029
, corresponding to the distance error
Figure 897509DEST_PATH_IMAGE030
That is:

Figure 693426DEST_PATH_IMAGE031
Figure 693426DEST_PATH_IMAGE031

Figure 259668DEST_PATH_IMAGE032
Figure 259668DEST_PATH_IMAGE032

其中，f c 为中心频率，该项引起的误差取决于R 0的大小，对其引起的误差通过数值仿真分析可知，R 0越大，误差越小，因此找到

Figure 468932DEST_PATH_IMAGE033
对应的临界值
Figure 28090DEST_PATH_IMAGE034
，即可将本方法适用的成像区域范围限定R x 为：Among them, f c is the center frequency, the error caused by this term depends on the size of R 0 , and the error caused by it is known through numerical simulation analysis. The larger the R 0 , the smaller the error, so find
Figure 468932DEST_PATH_IMAGE033
Corresponding critical value
Figure 28090DEST_PATH_IMAGE034
, the scope of the imaging area applicable to this method can be limited to R x as:

Figure 944093DEST_PATH_IMAGE035
Figure 944093DEST_PATH_IMAGE035

其中，成像范围

Figure 664925DEST_PATH_IMAGE036
为
Figure 112217DEST_PATH_IMAGE037
对应的临界值。Among them, the imaging range
Figure 664925DEST_PATH_IMAGE036
for
Figure 112217DEST_PATH_IMAGE037
the corresponding critical value.

成像平面数据

Figure 209486DEST_PATH_IMAGE038
可以表示为：Imaging plane data
Figure 209486DEST_PATH_IMAGE038
It can be expressed as:

Figure 245576DEST_PATH_IMAGE039
Figure 245576DEST_PATH_IMAGE039

成像平面数据进行方位向傅里叶变换（FT），则可以得到信号

Figure 137308DEST_PATH_IMAGE040
，定义
Figure 55586DEST_PATH_IMAGE041
为与
Figure 707278DEST_PATH_IMAGE026
对应的方位向波数。则信号可以表示为：The imaging plane data is subjected to azimuth Fourier transform (FT), and the signal can be obtained
Figure 137308DEST_PATH_IMAGE040
,definition
Figure 55586DEST_PATH_IMAGE041
for and
Figure 707278DEST_PATH_IMAGE026
The corresponding azimuthal wavenumber. Then the signal can be expressed as:

Figure 394611DEST_PATH_IMAGE042
Figure 394611DEST_PATH_IMAGE042

其中，

Figure 722824DEST_PATH_IMAGE043
定义为
Figure 862819DEST_PATH_IMAGE044
项的傅里叶变换，表示为：in,
Figure 722824DEST_PATH_IMAGE043
defined as
Figure 862819DEST_PATH_IMAGE044
The Fourier transform of the term, expressed as:

Figure 770732DEST_PATH_IMAGE045
Figure 770732DEST_PATH_IMAGE045

本发明实施例构造匹配滤波函数将式中

Figure 60374DEST_PATH_IMAGE046
项消除，以达到聚焦的目的。匹配滤波函数按如下公式构造：In the embodiment of the present invention, the matched filter function constructed by
Figure 60374DEST_PATH_IMAGE046
item is eliminated to achieve the purpose of focusing. The matched filter function is constructed as follows:

Figure 825068DEST_PATH_IMAGE047
Figure 825068DEST_PATH_IMAGE047

其中，

Figure 452359DEST_PATH_IMAGE048
定义为共轭，将
Figure 898383DEST_PATH_IMAGE049
与
Figure 294730DEST_PATH_IMAGE050
相乘即可完成方位向的匹配滤波：in,
Figure 452359DEST_PATH_IMAGE048
Defined as conjugate, the
Figure 898383DEST_PATH_IMAGE049
and
Figure 294730DEST_PATH_IMAGE050
Multiply to complete the matched filtering of the azimuth direction:

Figure 981057DEST_PATH_IMAGE051
。
Figure 981057DEST_PATH_IMAGE051
.

实施例中，对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像。In the embodiment, a two-dimensional inverse Fourier transform is performed on the matched filtered signal to obtain a focused image in a polar coordinate system.

具体实施时，对

Figure 95644DEST_PATH_IMAGE052
作二维逆傅里叶变换，得到聚焦后的时域信号，
Figure 79780DEST_PATH_IMAGE053
该信号是极坐标格式下的数据，可以得到点目标在极坐标系的二维聚焦图像。When implemented, the
Figure 95644DEST_PATH_IMAGE052
Do two-dimensional inverse Fourier transform to get the focused time domain signal,
Figure 79780DEST_PATH_IMAGE053
The signal is data in polar coordinate format, and a two-dimensional focused image of the point target in the polar coordinate system can be obtained.

实施例中，对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像。In the embodiment, interpolation processing is performed on the focused image in the polar coordinate system to obtain the focused image in the rectangular coordinate system.

具体实施时，将极坐标格式数据

Figure 596212DEST_PATH_IMAGE054
转直角坐标格式数据
Figure 702708DEST_PATH_IMAGE055
，得到直角坐标系下点目标的二维聚焦图像，也即实现了给定距离z p 平面的二维成像。该过程通过二维插值实现。根据极坐标与直角坐标的对应关系：In specific implementation, the polar coordinate format data is
Figure 596212DEST_PATH_IMAGE054
Convert data in Cartesian coordinate format
Figure 702708DEST_PATH_IMAGE055
, to obtain the two-dimensional focused image of the point target in the Cartesian coordinate system, that is, to realize the two-dimensional imaging of the plane at a given distance zp . This process is achieved by two-dimensional interpolation. According to the corresponding relationship between polar coordinates and rectangular coordinates:

Figure 55323DEST_PATH_IMAGE056
Figure 55323DEST_PATH_IMAGE056

其中，R 0’是用直角坐标x，y重新表示的R 0，

Figure 843151DEST_PATH_IMAGE057
为用直角坐标x，y重新表示的
Figure 214089DEST_PATH_IMAGE026
。where R 0 ' is R 0 re-expressed in Cartesian coordinates x , y ,
Figure 843151DEST_PATH_IMAGE057
is re-expressed with Cartesian coordinates x , y
Figure 214089DEST_PATH_IMAGE026
.

从而，可采用三次样条插值或者二维sinc插值实现极坐标数据到直角坐标数据的转换。Therefore, cubic spline interpolation or two-dimensional sinc interpolation can be used to realize the conversion of polar coordinate data to rectangular coordinate data.

实施例中，根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。In the embodiment, the frequency domain imaging of the circular scanning ground-based SAR is performed according to the focused image in the Cartesian coordinate system.

本实施例中，根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像，包括：根据所述直角坐标系下聚焦图像和预先设定的第二距离采样间隔，在场景区域内等间隔距离平面上进行层析分析。In this embodiment, performing the frequency domain imaging of the circular scanning ground-based SAR according to the focused image in the rectangular coordinate system includes: according to the focused image in the rectangular coordinate system and the preset second distance sampling interval, in the scene area The tomographic analysis was performed on the inner equally spaced plane.

具体实施时，对于整个场景区域，在等间隔d z 的距离平面上，重复进行上述平面成像，逐层实现二维成像，最后即可完成整个场景的三维成像。采样间隔d z 的采样规则如下：In specific implementation, for the entire scene area, the above plane imaging is repeated on the distance plane at equal intervals of d z to achieve two-dimensional imaging layer by layer, and finally the three-dimensional imaging of the entire scene can be completed. The sampling rules for the sampling interval d z are as follows:

已知以长度量纲表示的距离向分辨率为：It is known that the range resolution expressed in the length dimension is:

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那么，z方向的分辨率

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为：Then, the resolution in the z direction
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for:

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其中，in,

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因此，采样间隔d z 的设定应满足：Therefore, the setting of the sampling interval d z should satisfy:

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基于同一发明构思，本发明实施例还提供了一种圆周扫描地基SAR的频域成像装置，如下面的实施例所述。由于这些解决问题的原理与圆周扫描地基SAR的频域成像方法相似，因此装置的实施可以参见方法的实施，重复之处不再赘述。Based on the same inventive concept, an embodiment of the present invention also provides a frequency domain imaging device for circular scanning ground-based SAR, as described in the following embodiments. Since the principle of solving these problems is similar to the frequency domain imaging method of the circular scanning ground-based SAR, the implementation of the device can refer to the implementation of the method, and the repetition will not be repeated.

图4为本发明实施例中圆周扫描地基SAR的频域成像装置的结构图，如图4所示，该装置包括：FIG. 4 is a structural diagram of a frequency domain imaging device for circular scanning ground-based SAR in an embodiment of the present invention. As shown in FIG. 4 , the device includes:

回波信号获得模块401，用于获得圆周扫描地基SAR的回波信号；The echo signal obtaining module 401 is used to obtain the echo signal of the circular scanning ground-based SAR;

第一变换模块402，用于对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；The first transformation module 402 is used to perform range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain a range-compressed time-domain signal;

重采样模块403，用于根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；The resampling module 403 is used for resampling the distance-compressed time-domain signal according to the preset first distance sampling interval and geometric correspondence;

第二变换模块404，用于对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；The second transformation module 404 is used to perform a range-to-Fourier transform and an azimuth-to-Fourier transform on the resampled range-compressed time-domain signal to obtain a range-frequency-domain azimuth-frequency-domain signal;

匹配滤波模块405，用于根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；A matched filter module 405, configured to perform azimuth and direction matched filtering on the distance-frequency-domain, azimuth-frequency-domain signal according to a pre-configured matched filter function, and obtain a matched-filtered signal, and the matched filter function is pre-configured according to a conjugate algorithm;

第三变换模块406，用于对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；The third transformation module 406 is used to perform a two-dimensional inverse Fourier transform on the matched filtered signal to obtain a focused image in a polar coordinate system;

插值处理模块407，用于对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；The interpolation processing module 407 is used to perform interpolation processing on the focused image in the polar coordinate system to obtain the focused image in the rectangular coordinate system;

频域成像模块408，用于根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。The frequency domain imaging module 408 is configured to perform frequency domain imaging of the circular scanning ground-based SAR according to the focused image in the rectangular coordinate system.

一个实施例中，所述几何对应关系根据点目标到雷达在平面上的投影距离，点目标到雷达相位中心的距离和点目标所在平面与天线运动轨迹的垂直距离预先设定。In one embodiment, the geometric correspondence is preset according to the projected distance from the point target to the radar on the plane, the distance from the point target to the radar phase center, and the vertical distance between the plane where the point target is located and the trajectory of the antenna.

一个实施例中，所述第一距离采样间隔根据点目标到雷达相位中心的距离所对应的最大波数，点目标到雷达在平面上的投影距离所对应的最大波数，以及波束入射角预先设定。In one embodiment, the first distance sampling interval is preset according to the maximum wave number corresponding to the distance from the point target to the radar phase center, the maximum wave number corresponding to the projection distance from the point target to the radar on the plane, and the beam incident angle. .

一个实施例中，频域成像模块408进一步用于：根据所述直角坐标系下聚焦图像和预先设定的第二距离采样间隔，在场景区域内等间隔距离平面上进行层析分析。In one embodiment, the frequency domain imaging module 408 is further configured to: perform tomographic analysis on an equally spaced distance plane in the scene area according to the focused image in the Cartesian coordinate system and a preset second distance sampling interval.

综上所述，本发明实施例通过获得圆周扫描地基SAR的回波信号； 对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样；对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。本发明实施例通过重采样将回波信号从斜平面转换到成像平面，信号数据的转换，还通过傅里叶变换在频域进行目标的聚焦，计算效率高，成像速度快，方便进行实时成像，从而在保证成像质量的同时提高成像效率，实现场景的快速实时成像。To sum up, the embodiment of the present invention obtains the echo signal of the circular scanning ground-based SAR; performs range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain the range-compressed time domain signal; Determine the first distance sampling interval and geometric correspondence, resample the distance-compressed time-domain signal; perform range-direction Fourier transform and azimuth-direction Fourier transform on the resampled distance-compressed time-domain signal to obtain range-frequency-domain azimuth-frequency-domain signal; perform azimuth-matched filtering on the range-frequency-domain azimuth-frequency-domain signal according to a pre-configured matched filter function to obtain a matched-filtered signal, and the matched filter function is pre-constructed according to a conjugate algorithm; Perform a two-dimensional inverse Fourier transform on the matched filtered signal to obtain a focused image in a polar coordinate system; perform interpolation processing on the focused image in the polar coordinate system to obtain a focused image in a rectangular coordinate system; according to the rectangular coordinate system Focus the image down to perform frequency domain imaging of circular scanning ground-based SAR. In the embodiment of the present invention, the echo signal is converted from the oblique plane to the imaging plane by resampling, the signal data is converted, and the target is focused in the frequency domain through Fourier transform, the calculation efficiency is high, the imaging speed is fast, and real-time imaging is convenient. , so as to improve the imaging efficiency while ensuring the imaging quality, and realize the fast real-time imaging of the scene.

本领域内的技术人员应明白，本发明的实施例可提供为方法、系统、或计算机程序产品。因此，本发明可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本发明可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质（包括但不限于磁盘存储器、CD-ROM、光学存储器等）上实施的计算机程序产品的形式。As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

本发明是参照根据本发明实施例的方法、设备（系统）、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

最后应说明的是：以上所述实施例，仅为本发明的具体实施方式，用以说明本发明的技术方案，而非对其限制，本发明的保护范围并不局限于此，尽管参照前述实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，其依然可以对前述实施例所记载的技术方案进行修改或可轻易想到变化，或者对其中部分技术特征进行等同替换；而这些修改、变化或者替换，并不使相应技术方案的本质脱离本发明实施例技术方案的精神和范围，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应所述以权利要求的保护范围为准。Finally, it should be noted that the above-mentioned embodiments are only specific implementations of the present invention, and are used to illustrate the technical solutions of the present invention, but not to limit them. The protection scope of the present invention is not limited thereto, although referring to the foregoing The embodiment has been described in detail the present invention, those of ordinary skill in the art should understand: any person skilled in the art who is familiar with the technical field within the technical scope disclosed by the present invention can still modify the technical solutions described in the foregoing embodiments. Or can easily think of changes, or equivalently replace some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be covered in the present invention. within the scope of protection. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (8)

1.一种圆周扫描地基SAR的频域成像方法，其特征在于，包括：1. a frequency domain imaging method of circular scanning ground-based SAR, is characterized in that, comprises: 获得圆周扫描地基SAR的回波信号；Obtain the echo signal of the circular scanning ground-based SAR; 对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；Perform range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain a range compressed time domain signal; 根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样，所述第一距离采样间隔根据点目标到雷达相位中心的距离所对应的最大波数，点目标到雷达在平面上的投影距离所对应的最大波数，以及波束入射角预先设定；The range-compressed time-domain signal is resampled according to the preset first range sampling interval and geometric correspondence. The first range sampling interval is based on the maximum wave number corresponding to the distance from the point target to the radar phase center. The maximum wave number corresponding to the projection distance from the target to the radar on the plane, and the beam incident angle are preset; 对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；Perform range Fourier transform and azimuth Fourier transform on the resampled range-compressed time-domain signal to obtain the range-frequency-domain azimuth-frequency-domain signal; 根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；Perform azimuth matched filtering on the range-frequency-domain, azimuth-frequency-domain signal according to a pre-configured matched filter function to obtain a matched-filtered signal, and the matched filter function is pre-configured according to a conjugate algorithm; 对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；Perform a two-dimensional inverse Fourier transform on the matched filtered signal to obtain a focused image in the polar coordinate system; 对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；Perform interpolation processing on the focused image in the polar coordinate system to obtain the focused image in the rectangular coordinate system; 根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。According to the focused image in the rectangular coordinate system, the frequency domain imaging of the circular scanning ground-based SAR is performed. 2.如权利要求1所述的圆周扫描地基SAR的频域成像方法，其特征在于，所述几何对应关系根据点目标到雷达在平面上的投影距离，点目标到雷达相位中心的距离和点目标所在平面与天线运动轨迹的垂直距离预先设定。2. the frequency domain imaging method of circular scanning ground-based SAR as claimed in claim 1, is characterized in that, described geometrical correspondence is according to the projection distance of point target to radar on the plane, the distance of point target to radar phase center and point The vertical distance between the plane where the target is located and the trajectory of the antenna is preset. 3.如权利要求1所述的圆周扫描地基SAR的频域成像方法，其特征在于，根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像，包括：根据所述直角坐标系下聚焦图像和预先设定的第二距离采样间隔，在场景区域内等间隔距离平面上进行层析分析。3. the frequency domain imaging method of circular scanning ground-based SAR as claimed in claim 1, is characterized in that, according to the focused image under the described Cartesian coordinate system, carry out the frequency domain imaging of circular scanning ground-based SAR, comprising: according to the described Cartesian coordinates The tomographic analysis is performed on an equally spaced distance plane within the scene area under the tie of the focused image and a preset second distance sampling interval. 4.一种圆周扫描地基SAR的频域成像装置，其特征在于，包括：4. A frequency domain imaging device of circular scanning ground-based SAR, characterized in that, comprising: 回波信号获得模块，用于获得圆周扫描地基SAR的回波信号；The echo signal acquisition module is used to obtain the echo signal of the circular scanning ground-based SAR; 第一变换模块，用于对所述圆周扫描地基SAR的回波信号进行距离向逆傅里叶变换，得到距离压缩时域信号；The first transformation module is used to perform range inverse Fourier transform on the echo signal of the circular scanning ground-based SAR to obtain a range-compressed time-domain signal; 重采样模块，用于根据预先设定的第一距离采样间隔和几何对应关系，对所述距离压缩时域信号进行重采样，所述第一距离采样间隔根据点目标到雷达相位中心的距离所对应的最大波数，点目标到雷达在平面上的投影距离所对应的最大波数，以及波束入射角预先设定；The resampling module is used for resampling the distance compressed time domain signal according to the preset first distance sampling interval and geometric correspondence, and the first distance sampling interval is determined according to the distance from the point target to the radar phase center. The corresponding maximum wave number, the maximum wave number corresponding to the projected distance from the point target to the radar on the plane, and the beam incident angle are preset; 第二变换模块，用于对重采样后的距离压缩时域信号进行距离向傅里叶变换和方位向傅里叶变换，得到距离频域方位频域信号；The second transformation module is used to perform range-to-Fourier transform and azimuth-to-Fourier transform on the resampled range-compressed time-domain signal to obtain a range-frequency-domain azimuth-frequency-domain signal; 匹配滤波模块，用于根据预先构造的匹配滤波函数对所述距离频域方位频域信号进行方位向匹配滤波，得到匹配滤波后的信号，所述匹配滤波函数根据共轭算法预先构造；a matched filter module, configured to perform azimuth matched filtering on the distance-frequency-domain, azimuth-frequency-domain signal according to a pre-configured matched filter function, and obtain a matched-filtered signal, and the matched filter function is pre-configured according to a conjugate algorithm; 第三变换模块，用于对匹配滤波后的信号进行二维逆傅里叶变换，得到极坐标系下聚焦图像；The third transformation module is used to perform two-dimensional inverse Fourier transformation on the matched filtered signal to obtain a focused image in the polar coordinate system; 插值处理模块，用于对所述极坐标系下聚焦图像进行插值处理，得到直角坐标系下聚焦图像；an interpolation processing module for performing interpolation processing on the focused image in the polar coordinate system to obtain the focused image in the rectangular coordinate system; 频域成像模块，用于根据所述直角坐标系下聚焦图像，进行圆周扫描地基SAR的频域成像。The frequency domain imaging module is used to perform frequency domain imaging of the circular scanning ground-based SAR according to the focused image in the rectangular coordinate system. 5.如权利要求4所述的圆周扫描地基SAR的频域成像装置，其特征在于，所述几何对应关系根据点目标到雷达在平面上的投影距离，点目标到雷达相位中心的距离和点目标所在平面与天线运动轨迹的垂直距离预先设定。5. the frequency domain imaging device of circular scanning ground-based SAR as claimed in claim 4, is characterized in that, described geometrical correspondence is according to the projection distance of point target to radar on the plane, the distance of point target to radar phase center and point The vertical distance between the plane where the target is located and the trajectory of the antenna is preset. 6.如权利要求4所述的圆周扫描地基SAR的频域成像装置，其特征在于，频域成像模块进一步用于：根据所述直角坐标系下聚焦图像和预先设定的第二距离采样间隔，在场景区域内等间隔距离平面上进行层析分析。6. The frequency domain imaging device of circular scanning ground-based SAR as claimed in claim 4, wherein the frequency domain imaging module is further used for: focusing on the image under the Cartesian coordinate system and a preset second distance sampling interval , perform tomographic analysis on equally spaced planes within the scene area. 7.一种计算机设备，包括存储器、处理器及存储在存储器上并可在处理器上运行的计算机程序，其特征在于，所述处理器执行所述计算机程序时实现权利要求1至3任一所述方法。7. A computer device comprising a memory, a processor and a computer program stored on the memory and running on the processor, wherein the processor implements any one of claims 1 to 3 when the processor executes the computer program the method. 8.一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储有执行权利要求1至3任一所述方法的计算机程序。8. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing any one of the methods of claims 1 to 3.
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