CN104076343B - Satellite-borne three-channel SAR-GMTI self-adaptive clutter suppression method - Google Patents

Satellite-borne three-channel SAR-GMTI self-adaptive clutter suppression method Download PDF

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CN104076343B
CN104076343B CN201410290129.0A CN201410290129A CN104076343B CN 104076343 B CN104076343 B CN 104076343B CN 201410290129 A CN201410290129 A CN 201410290129A CN 104076343 B CN104076343 B CN 104076343B
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CN104076343A (en
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王彤
李永康
张颖
吴建新
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Xidian University
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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
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9029—SAR image post-processing techniques specially adapted for moving target detection within a single SAR image or within multiple SAR images taken at the same time
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • 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
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G01S7/2928—Random or non-synchronous interference pulse cancellers

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  • Radar Systems Or Details Thereof (AREA)

Abstract

本发明公开了一种星载三通道SAR‑GMTI自适应杂波抑制方法，涉及自适应杂波抑制，包括：步骤1，得到距离压缩后的距离多普勒域目标回波信号；步骤2，得到距离压缩后的距离多普勒域回波信号；步骤3，三个通道的第l号待检测距离单元的数据Xl；步骤4，得到第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据；步骤5，令待检测距离单元的数目l增加1，重复步骤2～4，直至l等于L，即完成L个距离单元杂波抑制，输出L个距离单元杂波抑制后的数据Y。本发明用于抑制三通道SAR‑GMTI系统接收到的地杂波。

The invention discloses a space-borne three-channel SAR-GMTI adaptive clutter suppression method, which relates to adaptive clutter suppression, comprising: step 1, obtaining a range-compressed range Doppler domain target echo signal; step 2, Obtain the range Doppler domain echo signal after the range compression; Step 3, the data X l of the No. 1 distance unit to be detected of the three channels; Step 4, obtain each Doppler unit of the No. 1 distance unit to be detected The data after adaptive clutter suppression; step 5, increase the number l of distance units to be detected by 1, repeat steps 2 to 4 until l is equal to L, that is, the clutter suppression of L distance units is completed, and L distance units are output Data Y after clutter suppression. The invention is used for suppressing ground clutter received by a three-channel SAR-GMTI system.

Description

星载三通道SAR-GMTI自适应杂波抑制方法Adaptive clutter suppression method for spaceborne three-channel SAR-GMTI

技术领域technical field

本发明属于雷达技术领域，涉及自适应杂波抑制，具体的说是一种星载三通道合成孔径雷达(Synthetic Aperture Radar，SAR)-地面运动目标检测(Ground MovingTarget Indication，GMTI)自适应杂波抑制方法，用于抑制三通道SAR-GMTI系统接收到的地杂波。The invention belongs to the field of radar technology, and relates to adaptive clutter suppression, in particular to a spaceborne three-channel synthetic aperture radar (Synthetic Aperture Radar, SAR)-ground moving target detection (Ground Moving Target Indication, GMTI) adaptive clutter The suppression method is used to suppress the ground clutter received by the three-channel SAR-GMTI system.

背景技术Background technique

合成孔径概念的提出和SAR的发明是二十世纪雷达技术发展史上的一次重大突破。SAR通过发射大带宽信号获得距离上的高分辨能力，依靠雷达平台与目标间的相对运动形成大的合成孔径，从而获取方位上的高分辨能力。距离和方位高分辨率的获得使SAR能够全天候、全天时、远距离地获取类似于光学成像的大测绘带二维图像，大大提高了雷达的信息获取能力。鉴于以上优点，近年来SAR得到了广泛的关注和应用。其中，星载三通道SAR-GMTI系统因其在交通监控和战场侦察中的重要作用而成为一个研究热点。The introduction of the concept of synthetic aperture and the invention of SAR are a major breakthrough in the history of radar technology development in the 20th century. SAR obtains high-resolution capabilities in distance by transmitting large-bandwidth signals, and relies on the relative motion between the radar platform and the target to form a large synthetic aperture, thereby obtaining high-resolution capabilities in azimuth. The acquisition of high-resolution distance and azimuth enables SAR to acquire large-scale two-dimensional images similar to optical imaging all-weather, all-day, and long-distance, which greatly improves the information acquisition ability of radar. In view of the above advantages, SAR has been widely concerned and applied in recent years. Among them, the spaceborne three-channel SAR-GMTI system has become a research hotspot because of its important role in traffic monitoring and battlefield reconnaissance.

对于星载SAR-GMTI系统，由于雷达工作在下视状态，回波中不可避免地包含了大量的地杂波，且地杂波的频谱可能与目标的频谱重叠，因而目标可能会被强地杂波淹没，从而严重影响星载SAR-GMTI系统对目标的检测。为解决上述问题，需要发明有效的杂波抑制方法来抑制地杂波，提高系统对目标的检测性能。For the spaceborne SAR-GMTI system, since the radar works in the downward-looking state, the echo inevitably contains a large amount of ground clutter, and the spectrum of the ground clutter may overlap with the spectrum of the target, so the target may be strongly cluttered. The waves are submerged, which seriously affects the detection of the target by the spaceborne SAR-GMTI system. In order to solve the above problems, it is necessary to invent an effective clutter suppression method to suppress ground clutter and improve the system's detection performance on targets.

偏置相位中心天线(Displaced Phase Centre Antenna，DPCA)技术是最常用的两通道SAR-GMTI技术之一，该技术通过将两幅图像两两相减来抑制杂波。但是，DPCA技术是针对两通道SAR-GMTI系统设计的。当SAR-GMTI系统通道数大于二时，DPCA技术不能完全积累目标信号的能量。此外，由于DPCA技术仅利用两个自由度来抑制杂波，杂波抑制能力非常有限。因此，对于多通道SAR-GMTI系统，DPCA技术不是最优的。为解决上述问题，德国高能物理与雷达技术研究所的Ender、Cerutti-Maori等人提出了基于自适应杂波抑制的多通道SAR-GMTI方法，该方法在距离多普勒域进行自适应杂波抑制。发明人发现，上述方法忽略了相邻多普勒单元数据的相关性，从而限制了多通道SAR-GMTI系统的杂波抑制性能，进而限制了系统对目标的检测能力。Displaced Phase Center Antenna (DPCA) technology is one of the most commonly used two-channel SAR-GMTI technologies, which suppresses clutter by subtracting two images two by two. However, the DPCA technique is designed for the two-channel SAR-GMTI system. When the channel number of SAR-GMTI system is greater than two, DPCA technology cannot fully accumulate the energy of the target signal. In addition, since the DPCA technique only utilizes two degrees of freedom to suppress clutter, the clutter suppression capability is very limited. Therefore, for multi-channel SAR-GMTI systems, DPCA technique is not optimal. In order to solve the above problems, Ender, Cerutti-Maori and others from the German Institute of High Energy Physics and Radar Technology proposed a multi-channel SAR-GMTI method based on adaptive clutter suppression. inhibition. The inventors found that the above method ignores the correlation of adjacent Doppler unit data, thereby limiting the clutter suppression performance of the multi-channel SAR-GMTI system, and further limiting the system's ability to detect targets.

发明内容Contents of the invention

针对上述多通道SAR-GMTI距离多普勒域自适应杂波抑制方法的缺点，本发明提出了一种星载三通道SAR-GMTI自适应杂波抑制方法，该方法在距离多普勒域对每个多普勒单元数据联合相邻的两个多普勒单元数据进行自适应杂波抑制。Aiming at the shortcomings of the above-mentioned multi-channel SAR-GMTI range-Doppler domain adaptive clutter suppression method, the present invention proposes a spaceborne three-channel SAR-GMTI adaptive clutter suppression method. The data of each Doppler unit is combined with the data of two adjacent Doppler units to perform adaptive clutter suppression.

为达到上述目的，本发明采用以下技术方案予以实现。In order to achieve the above object, the present invention adopts the following technical solutions to achieve.

一种星载三通道SAR-GMTI自适应杂波抑制方法，其特征在于，包括以下步骤：A spaceborne three-channel SAR-GMTI adaptive clutter suppression method is characterized in that it comprises the following steps:

步骤1，建立目标原始回波信号模型，根据目标原始回波信号得到距离频率域目标回波信号；根据距离频率域目标回波信号构造距离频率域距离压缩滤波器；根据距离频率域目标回波信号和距离频率域距离压缩滤波器得到距离压缩后的距离多普勒域目标回波信号；Step 1, establish the target original echo signal model, and obtain the target echo signal in the range frequency domain according to the original target echo signal; construct the range frequency domain range compression filter according to the target echo signal in the range frequency domain; The range compression filter in the signal and range frequency domain obtains the target echo signal in the range Doppler domain after range compression;

步骤2，星载三通道SAR-GMTI系统接收三通道原始回波信号，对接收到的三通道原始回波信号分别进行距离向傅里叶变换得到距离频率域回波信号，再根据距离频率域距离压缩滤波器对距离频率域回波信号分别进行距离压缩，得到距离压缩之后的回波信号，并将距离压缩之后的回波信号变换到距离多普勒域，得到距离压缩后的距离多普勒域回波信号；Step 2. The spaceborne three-channel SAR-GMTI system receives the three-channel original echo signals, and performs range-to-Fourier transform on the received three-channel original echo signals to obtain the range-frequency domain echo signals, and then according to the distance-frequency domain The range compression filter performs range compression on the echo signals in the range frequency domain to obtain the echo signals after range compression, and transforms the echo signals after range compression into the range Doppler domain to obtain the range Doppler after range compression. Le field echo signal;

步骤3，从每一通道距离压缩后的距离多普勒域回波信号中取出第l号待检测距离单元的数据xl，i，i表示通道序号，i＝1，2，3，l＝1，...，L，L为需要进行目标检测的距离单元的个数，则三个通道的第l号待检测距离单元的数据Xl表示为：Step 3, extract the data x l, i of the No. 1 range unit to be detected from the range-Doppler domain echo signal after the range compression of each channel, i represents the channel number, i=1, 2, 3, l= 1, ..., L, L is the number of distance units that need to be detected, then the data X1 of the No. l distance unit to be detected of the three channels is expressed as:

Xl＝[xl，1，xl，2，xl，3]Xl = [xl , 1 , xl , 2 , xl , 3 ]

其中，xl，1为第1通道第l号距离单元的数据，xl，2为第2通道第l号距离单元的数据，xl，3为第3通道第l号距离单元的数据，xl，1、xl，2和xl，3维数均为K×1，K为需要进行目标检测的多普勒单元的个数；Wherein, x 1, 1 is the data of the No. 1 distance unit of the 1st channel, x 1, 2 is the data of the No. 1 distance unit of the 2nd channel, x 1, 3 is the data of the No. 1 distance unit of the 3rd channel, x l, 1 , x l, 2 and x l, 3 dimensions are all K×1, K is the number of Doppler units that need to detect the target;

步骤4，在三个通道的第l号待检测距离单元的数据Xl中，构建三个相邻多普勒单元的数据的空时数据矢量zl，k；再根据步骤1得到的距离压缩后的距离多普勒域目标回波信号构造三个相邻多普勒单元的目标的空时导向矢量Dl，k；根据三个相邻多普勒单元的目标的空时导向矢量Dl，k求解权向量wl，k；利用权向量wl，k对空时数据矢量zl，k进行自适应杂波抑制，得到第l号待检测距离单元第k个多普勒单元的自适应杂波抑制后的数据yl，k；再完成第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据yl＝[yl，1，yl，2，…，yl，K]T；Step 4, in the data X l of the No. l distance unit to be detected of the three channels, construct the space-time data vector z l, k of the data of three adjacent Doppler units; then compress according to the distance obtained in step 1 Construct the space-time steering vector D l, k of the target of the three adjacent Doppler units based on the echo signal of the target in the range Doppler domain; according to the space-time steering vector D l of the target of the three adjacent Doppler units , k to solve the weight vector w l, k ; use the weight vector w l, k to perform adaptive clutter suppression on the space-time data vector z l, k , and obtain the automatic Adapt to the data y l after clutter suppression, k ; then complete the data y l after adaptive clutter suppression of each Doppler unit of the No. 1 distance unit to be detected = [y l, 1 , y l, 2 , ..., y l, K ] T ;

步骤5，令待检测距离单元的数目l增加1，重复步骤2～4，直至l等于L，即完成L个距离单元杂波抑制，输出L个距离单元杂波抑制后的数据Y，Y＝[y1，y2，…yl…，yL]。Step 5: Increase the number l of range units to be detected by 1, repeat steps 2-4 until l is equal to L, that is, complete the suppression of L range unit clutter, and output the data Y after L range unit clutter suppression, Y= [y 1 , y 2 , . . . y l . . . , y L ].

上述技术方案的特点和进一步改进在于：The characteristics and further improvement of the above-mentioned technical scheme are:

(1)步骤1包括以下子步骤：(1) Step 1 includes the following sub-steps:

1a)目标到第i个通道的瞬时距离表示为：1a) The instantaneous distance from the target to the i-th channel is expressed as:

其中，vx为目标方位向速度，vy为目标距离向速度，y0为慢时间ta＝0时目标的纵坐标，i＝1，2，3。Wherein, v x is the target azimuth velocity, v y is the target range velocity, y 0 is the ordinate of the target when the slow time t a =0, i=1,2,3.

第i个通道接收到的目标原始回波信号表示为：The target original echo signal received by the i-th channel is expressed as:

其中，A0为反映动目标散射率的复常数，tr为快时间，c为光速，wa(ta)为方位包络，wr(tr)为距离包络，fc为载频，Kr为系统发射信号的调频率，ta为慢时间，i＝1，2，3。Among them, A 0 is the complex constant reflecting the scattering rate of the moving target, t r is the fast time, c is the speed of light, w a (t a ) is the azimuth envelope, w r (t r ) is the distance envelope, f c is the load frequency, K r is the modulation frequency of the signal transmitted by the system, t a is the slow time, i=1, 2, 3.

1b)根据公式(2)，得到距离频率域目标回波信号，表达式为：1b) According to the formula (2), the target echo signal in the range frequency domain is obtained, the expression is:

其中，fr为距离频率，ta为慢时间，Wr(fr)为距离频率包络，fc为载频，Kr为系统发射信号的调频率，A0为反映动目标散射率的复常数，c为光速，wa(ta)为方位包络。Among them, fr is the range frequency, t a is the slow time, W r ( fr ) is the range frequency envelope, f c is the carrier frequency, K r is the modulation frequency of the system's transmitted signal, and A 0 is the scattering rate reflecting the moving target The complex constant of , c is the speed of light, w a (t a ) is the azimuth envelope.

1c)根据距离频率域目标回波信号的表达式，构造距离频率域距离压缩滤波器为：1c) According to the expression of the target echo signal in the range frequency domain, construct the range compression filter in the range frequency domain as:

其中，fr为距离频率，Kr为系统发射信号的调频率。Among them, f r is the distance frequency, and K r is the modulation frequency of the signal transmitted by the system.

1d)利用距离频率域距离压缩滤波器对距离频率域目标回波信号进行距离压缩，得到距离压缩之后的目标回波信号，根据式(3)和式(2)，距离压缩之后的目标回波信号表达式为：1d) Use the distance compression filter in the range frequency domain to perform range compression on the target echo signal in the range frequency domain to obtain the target echo signal after range compression. According to formula (3) and formula (2), the target echo signal after range compression The signal expression is:

其中，fr为距离频率，ta为慢时间，Wr(fr)为距离频率包络，fc为载频，Kr为系统发射信号的调频率，A0为反映动目标散射率的复常数，c为光速，wa(ta)为方位包络。Among them, fr is the range frequency, t a is the slow time, W r ( fr ) is the range frequency envelope, f c is the carrier frequency, K r is the modulation frequency of the system's transmitted signal, and A 0 is the scattering rate reflecting the moving target The complex constant of , c is the speed of light, w a (t a ) is the azimuth envelope.

1e)对距离压缩后的目标回波信号进行距离向逆傅里叶变换和方位向傅里叶变换，得到距离压缩后的距离多普勒域目标回波信号，距离压缩后的距离多普勒域目标回波信号的表达式：1e) Perform range inverse Fourier transform and azimuth Fourier transform on the range-compressed target echo signal to obtain the range-compressed range-Doppler domain target echo signal, and the range-compressed range Doppler domain The expression of domain target echo signal:

其中，tr为快时间，B为发射信号的带宽，A0为反映动目标散射率的复常数，c为光速，fa为多普勒频率，Wa(fa)为多普勒频率包络，λ为信号波长，va为雷达平台速度，vx为目标方位向速度，vy为目标距离向速度，y0为慢时间ta＝0时目标的纵坐标，d为相邻通道的等效相位中心的间距。Among them, t r is the fast time, B is the bandwidth of the transmitted signal, A 0 is the complex constant reflecting the scattering rate of the moving target, c is the speed of light, f a is the Doppler frequency, W a (f a ) is the Doppler frequency envelope, λ is the signal wavelength, v a is the velocity of the radar platform, v x is the target azimuth velocity, v y is the target range velocity, y 0 is the ordinate of the target when the slow time t a =0, d is the adjacent The distance between the equivalent phase centers of the channels.

(2)步骤4包括以下子步骤：(2) Step 4 includes the following sub-steps:

4a)在三个通道的第l号待检测距离单元的数据Xl中，选择k-1、k和k+1个多普勒单元的数据构成空时数据矢量zl，k：4a) Among the data X 1 of the No. 1 distance unit to be detected in the three channels, the data of k-1, k and k+1 Doppler units are selected to form the space-time data vector z 1, k :

其中，表示第1通道第l号距离单元第k个多普勒单元的数据，表示第2通道第l号距离单元第k个多普勒单元的数据，表示第3通道第l号距离单元第k个多普勒单元的数据，表示第k个多普勒单元的多普勒频率，上标T表示非共轭转置，k-1、k和k+1个多普勒单元为三个相邻多普勒单元。in, Indicates the data of the kth Doppler unit of the first channel and the No. l range unit, Indicates the data of the kth Doppler unit of the No. 1 range unit of the second channel, Represents the data of the kth Doppler unit of the No. 1 range unit of the third channel, Indicates the Doppler frequency of the k-th Doppler unit, the superscript T indicates the non-conjugate transpose, and the k-1, k and k+1 Doppler units are three adjacent Doppler units.

4b)根据距离多普勒域目标回波信号的表达式(6)，构造位于第l号距离单元第k-1、k和k+1个多普勒单元的目标的空时导向矢量Dl，k：4b) According to the expression (6) of the target echo signal in the range Doppler domain, construct the space-time steering vector D l of the target located in the k-1, k and k+1 Doppler units of the l-th range unit , k :

其中，为第l号距离单元第k个多普勒单元的目标的导向矢量；为第l号距离单元第k-1个多普勒单元的目标的导向矢量；为第l号距离单元第k+1个多普勒单元的目标的导向矢量；in, Be the steering vector of the target of the k-th Doppler cell in the l-th range cell; Be the steering vector of the target of the k-1 Doppler unit of the No. l range unit; is the steering vector of the target of the k+1 Doppler unit of the No. l range unit;

4c)通过求解以下公式(10)求解权向量wl，k，得到 4c) Solve the weight vector w l,k by solving the following formula (10), get

其中，为第k个多普勒单元的协方差矩阵，Dl，k为第l号距离单元第k-1、k和k+1个多普勒单元的目标的空时导向矢量，表示第1通道第l号距离单元第k个多普勒单元的数据，表示第2通道第l号距离单元第k个多普勒单元的数据，表示第3通道第l号距离单元第k个多普勒单元的数据。in, is the covariance matrix of the kth Doppler unit, D l, k is the space-time steering vector of the target of the k-1, k and k+1 Doppler units of the l-th range unit, Indicates the data of the kth Doppler unit of the first channel and the No. l range unit, Indicates the data of the kth Doppler unit of the No. 1 range unit of the second channel, Indicates the data of the kth Doppler unit in the range unit l of the third channel.

4d)利用权向量wl，k对空时数据矢量zl，k进行自适应杂波抑制：4d) Using the weight vector w l, k to perform adaptive clutter suppression on the space-time data vector z l, k :

其中，yl，k为第l号待检测距离单元第k个多普勒单元的自适应杂波抑制后的数据，wl，k为权向量，上标H表示共轭转置。Among them, y l, k are the data after adaptive clutter suppression of the kth Doppler unit of the lth distance unit to be detected, w l, k are the weight vectors, and the superscript H means conjugate transposition.

4e)令k增加1，重复步骤4a)～4d)，直至k等于K，K为需要进行目标检测的多普勒单元的个数，得到第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据：yl＝[yl，1，yl，2，…，yl，K]T。4e) increase k by 1, repeat steps 4a) to 4d), until k is equal to K, K is the number of Doppler units that need to be detected, and the number of each Doppler unit of the No. 1 distance unit to be detected is obtained Data after adaptive clutter suppression: y l =[y l, 1 , y l, 2 , . . . , y l, K ] T .

本发明与现有技术相比具有以下优点：Compared with the prior art, the present invention has the following advantages:

1)本发明考虑到了相邻多普勒通道数据的相干性，对每个多普勒单元的数据采用联合相邻两个多普勒单元的数据的方法进行自适应杂波抑制，能更好的抑制杂波；1) The present invention has taken into account the coherence of adjacent Doppler channel data, and adopts the method of uniting the data of two adjacent Doppler units for the data of each Doppler unit to carry out adaptive clutter suppression, which can be better suppression of clutter;

2)本发明能够完全积累所有通道的信号的能量，能显著提高系统最终的输出信杂噪比，有利于提高系统对目标的检测性能；2) The present invention can completely accumulate the energy of the signals of all channels, can significantly improve the final output signal-to-noise ratio of the system, and is conducive to improving the detection performance of the system to the target;

4)本发明采用自适应的方法进行杂波抑制，能适应杂波的内部运动以及系统通道失配，适用范围更广。4) The present invention uses an adaptive method to suppress clutter, which can adapt to the internal movement of clutter and system channel mismatch, and has a wider application range.

附图说明Description of drawings

下面结合附图和具体实施方式对本发明做进一步说明。The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

图1是本发明的实现流程图；Fig. 1 is the realization flowchart of the present invention;

图2是斜距平面星载三通道SAR-GMTI系统观测几何；其中横坐标表示方位向，纵坐标表示斜距向；Figure 2 is the observation geometry of the slant-range plane spaceborne three-channel SAR-GMTI system; where the abscissa represents the azimuth, and the ordinate represents the slant-range direction;

图3是距离压缩后杂波抑制前距离多普勒域数据的仿真结果图；其中横坐标表示距离门，纵坐标表示多普勒频率；Fig. 3 is a simulation result diagram of range Doppler domain data before clutter suppression after range compression; wherein the abscissa represents the range gate, and the ordinate represents the Doppler frequency;

图4是用本发明技术进行杂波抑制后距离多普勒域数据的仿真结果图；其中横坐标表示距离门，纵坐标表示多普勒频率；Fig. 4 is the simulation result figure of range Doppler domain data after carrying out clutter suppression with the technology of the present invention; Wherein the abscissa represents the range gate, and the ordinate represents the Doppler frequency;

图5是距离多普勒域杂波抑制效果比较图；其中横坐标表示多普勒频率，纵坐标表示杂波抑制比。Fig. 5 is a comparison chart of clutter suppression effects in the range Doppler domain; where the abscissa represents the Doppler frequency, and the ordinate represents the clutter suppression ratio.

具体实施方式detailed description

参照图1，说明本发明的星载三通道SAR-GMTI自适应杂波抑制方法，用于抑制三通道SAR-GMTI系统接收到的地杂波，其具体步骤如下：With reference to Fig. 1, illustrate the spaceborne three-channel SAR-GMTI adaptive clutter suppression method of the present invention, be used for suppressing the ground clutter that three-channel SAR-GMTI system receives, its specific steps are as follows:

步骤1，建立目标原始回波信号模型，根据目标原始回波信号得到距离频率域目标回波信号；根据距离频率域目标回波信号构造距离频率域距离压缩滤波器；根据距离频率域目标回波信号和距离频率域距离压缩滤波器得到距离压缩后的距离多普勒域目标回波信号。Step 1, establish the target original echo signal model, and obtain the target echo signal in the range frequency domain according to the original target echo signal; construct the range frequency domain range compression filter according to the target echo signal in the range frequency domain; The range compression filter in the signal and range frequency domain obtains the target echo signal in the range Doppler domain after range compression.

斜距平面星载三通道SAR-GMTI系统观测几何如图2所示：通道1与通道2之间的等效相位中心的间距为d，通道2与通道3之间的等效相位中心的间距为d，雷达平台速度为va。系统工作时，通道2发射信号。接收信号时，三个通道同时接收。在慢时间ta＝0时，通道1等效相位中心的坐标为(0，0)，通道2等效相位中心的坐标为(0，-d)，通道3等效相位中心的坐标为(0，-2d)，目标的坐标为(0，y0)。目标匀速运动，且沿方位向的速度为vx，沿距离向的速度为vy。The observation geometry of the slant-distance plane spaceborne three-channel SAR-GMTI system is shown in Figure 2: the distance between the equivalent phase centers of channel 1 and channel 2 is d, and the distance between the equivalent phase centers of channel 2 and channel 3 is is d, and the velocity of the radar platform is v a . When the system is working, channel 2 transmits signal. When receiving a signal, the three channels receive simultaneously. When the slow time t a =0, the coordinates of the equivalent phase center of channel 1 are (0, 0), the coordinates of the equivalent phase center of channel 2 are (0, -d), and the coordinates of the equivalent phase center of channel 3 are ( 0, -2d), the coordinates of the target are (0, y 0 ). The target moves at a uniform speed, and the velocity along the azimuth direction is v x , and the velocity along the distance direction is v y .

为了后面的推导方便，下面给出目标原始回波信号模型。For the convenience of subsequent derivation, the target original echo signal model is given below.

1a)目标到第i个通道的瞬时距离表示为：1a) The instantaneous distance from the target to the i-th channel is expressed as:

其中，vx为目标方位向速度，vy为目标距离向速度，y0为慢时间ta＝0时目标的纵坐标，i表示通道序号，i＝1，2，3。Among them, v x is the target azimuth velocity, v y is the target range velocity, y 0 is the ordinate of the target when the slow time t a =0, i represents the channel number, i=1,2,3.

第i个通道接收到的目标原始回波信号表示为：The target original echo signal received by the i-th channel is expressed as:

其中，A0为反映动目标散射率的复常数，tr为快时间，c为光速，wa(ta)为方位包络，wr(tr)为距离包络，fc为载频，Kr为系统发射信号的调频率，ta为慢时间，i＝1，2，3。Among them, A 0 is the complex constant reflecting the scattering rate of the moving target, t r is the fast time, c is the speed of light, w a (t a ) is the azimuth envelope, w r (t r ) is the distance envelope, f c is the load frequency, K r is the modulation frequency of the signal transmitted by the system, t a is the slow time, i=1, 2, 3.

1b)根据公式(2)，得到距离频率域目标回波信号，表达式为：1b) According to the formula (2), the target echo signal in the range frequency domain is obtained, the expression is:

其中，fr为距离频率，ta为慢时间，Wr(fr)为距离频率包络，fc为载频，Kr为系统发射信号的调频率，A0为反映动目标散射率的复常数，c为光速，wa(ta)为方位包络。Among them, fr is the range frequency, t a is the slow time, W r ( fr ) is the range frequency envelope, f c is the carrier frequency, K r is the modulation frequency of the system's transmitted signal, and A 0 is the scattering rate reflecting the moving target The complex constant of , c is the speed of light, w a (t a ) is the azimuth envelope.

为提高效率，本发明在距离频率域以相位相乘的方式对系统接收到的三通道原始回波信号分别进行距离压缩。In order to improve the efficiency, the present invention performs range compression on the three-channel original echo signals received by the system in the range-frequency domain by means of phase multiplication.

1c)根据距离频率域目标回波信号的表达式，构造距离频率域距离压缩滤波器为：1c) According to the expression of the target echo signal in the range frequency domain, construct the range compression filter in the range frequency domain as:

其中，fr为距离频率，Kr为系统发射信号的调频率。Among them, f r is the distance frequency, and K r is the modulation frequency of the signal transmitted by the system.

1d)利用距离频率域距离压缩滤波器对距离频率域目标回波信号进行距离压缩，得到距离压缩之后的目标回波信号，根据式(3)和式(2)，距离压缩之后的目标回波信号表达式为：1d) Use the distance compression filter in the range frequency domain to perform range compression on the target echo signal in the range frequency domain to obtain the target echo signal after range compression. According to formula (3) and formula (2), the target echo signal after range compression The signal expression is:

其中，fr为距离频率，ta为慢时间，Wr(fr)为距离频率包络，fc为载频，Kr为系统发射信号的调频率，A0为反映动目标散射率的复常数，c为光速，wa(ta)为方位包络。Among them, fr is the range frequency, t a is the slow time, W r ( fr ) is the envelope of the range frequency, f c is the carrier frequency, K r is the modulation frequency of the transmitted signal of the system, and A 0 is the scattering rate reflecting the moving target The complex constant of , c is the speed of light, w a (t a ) is the azimuth envelope.

1e)对距离压缩后的目标回波信号进行距离向逆傅里叶变换和方位向傅里叶变换，得到距离压缩后的距离多普勒域目标回波信号，距离压缩后的距离多普勒域目标回波信号的表达式：1e) Perform range inverse Fourier transform and azimuth Fourier transform on the range-compressed target echo signal to obtain the range-compressed range-Doppler domain target echo signal, and the range-compressed range Doppler domain The expression of domain target echo signal:

其中，tr为快时间，B为发射信号的带宽，A0为反映动目标散射率的复常数，c为光速，fa为多普勒频率，Wa(fa)为多普勒频率包络，λ为信号波长，va为雷达平台速度，vx为目标方位向速度，vy为目标距离向速度，y0为慢时间ta＝0时目标的纵坐标，d为相邻通道的等效相位中心的间距。Among them, t r is the fast time, B is the bandwidth of the transmitted signal, A 0 is the complex constant reflecting the scattering rate of the moving target, c is the speed of light, f a is the Doppler frequency, W a (f a ) is the Doppler frequency envelope, λ is the signal wavelength, v a is the velocity of the radar platform, v x is the target azimuth velocity, v y is the target range velocity, y 0 is the ordinate of the target when the slow time t a =0, d is the adjacent The distance between the equivalent phase centers of the channels.

步骤2，星载三通道SAR-GMTI系统接收三通道原始回波信号，对接收到的三通道原始回波信号分别进行距离向傅里叶变换就得到距离频率域回波信号，再根据距离频率域距离压缩滤波器对距离频率域回波信号分别进行距离压缩，得到距离压缩之后的回波信号，并将距离压缩之后的回波信号变换到距离多普勒域，得到距离压缩后的距离多普勒域回波信号。Step 2. The spaceborne three-channel SAR-GMTI system receives the three-channel original echo signals, and performs range-to-Fourier transform on the received three-channel original echo signals to obtain the range-frequency domain echo signals, and then according to the range-frequency The domain range compression filter performs range compression on the echo signals in the range frequency domain to obtain the echo signals after range compression, and transforms the echo signals after range compression into the range Doppler domain to obtain the distance compression after the range compression. The echo signal in the Puler domain.

步骤3，从每一通道距离压缩后的距离多普勒域回波信号中取出第l号待检测距离单元的数据xl，i，i表示通道序号，i＝1，2，3，l＝1，...，L，L为需要进行目标检测的距离单元的个数，则三个通道的第l号待检测距离单元的数据Xl表示为：Step 3, extract the data x l, i of the No. 1 range unit to be detected from the range-Doppler domain echo signal after the range compression of each channel, i represents the channel number, i=1, 2, 3, l= 1, ..., L, L is the number of distance units that need to be detected, then the data X1 of the No. l distance unit to be detected of the three channels is expressed as:

Xl＝[xl，1，xl，2，xl，3]Xl = [xl , 1 , xl , 2 , xl , 3 ]

其中，xl，1为第1通道第l号距离单元的数据，xl，2为第2通道第l号距离单元的数据，xl，3为第3通道第l号距离单元的数据，xl，1、xl，2和xl，3维数均为K×1，K为需要进行目标检测的多普勒单元的个数。Wherein, x 1, 1 is the data of the No. 1 distance unit of the 1st channel, x 1, 2 is the data of the No. 1 distance unit of the 2nd channel, x 1, 3 is the data of the No. 1 distance unit of the 3rd channel, The dimensions of x l,1 , x l,2 and x l,3 are all K×1, and K is the number of Doppler units required for target detection.

步骤4，在三个通道的第l号待检测距离单元的数据Xl中，构建三个相邻多普勒单元的数据的空时数据矢量zl，k；再根据步骤1得到的距离压缩后的距离多普勒域目标回波信号构造三个相邻多普勒单元的目标的空时导向矢量Dl，k；根据三个相邻多普勒单元的目标的空时导向矢量Dl，k求解权向量wl，k；利用权向量wl，k对空时数据矢量zl，k进行自适应杂波抑制，得到第l号待检测距离单元第k个多普勒单元的自适应杂波抑制后的数据yl，k；再完成第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据yl＝[yl，1，yl，2，…，yl，K]T。Step 4, in the data X l of the No. l distance unit to be detected of the three channels, construct the space-time data vector z l, k of the data of three adjacent Doppler units; then compress according to the distance obtained in step 1 Construct the space-time steering vector D l, k of the target of the three adjacent Doppler units based on the echo signal of the target in the range Doppler domain; according to the space-time steering vector D l of the target of the three adjacent Doppler units , k to solve the weight vector w l, k ; use the weight vector w l, k to perform adaptive clutter suppression on the space-time data vector z l, k , and obtain the automatic Adapt to the data y l after clutter suppression, k ; then complete the data y l after adaptive clutter suppression of each Doppler unit of the No. 1 distance unit to be detected = [y l, 1 , y l, 2 , ..., y l, K ] T .

4a)在三个通道的第l号待检测距离单元的数据Xl中，选择第k-1、k和k+1个多普勒单元的数据构成空时数据矢量zl，k：4a) Among the data X 1 of the No. 1 distance unit to be detected in the three channels, select the data of the k-1, k and k+1 Doppler units to form the space-time data vector z 1, k :

其中，表示第1通道第l号距离单元第k个多普勒单元的数据，表示第2通道第l号距离单元第k个多普勒单元的数据，表示第3通道第l号距离单元第k个多普勒单元的数据，表示第k个多普勒单元的多普勒频率，上标T表示非共轭转置，k-1、k和k+1个多普勒单元为三个相邻多普勒单元。in, Indicates the data of the kth Doppler unit of the first channel and the No. l range unit, Indicates the data of the kth Doppler unit of the No. 1 range unit of the second channel, Represents the data of the kth Doppler unit of the No. 1 range unit of the third channel, Indicates the Doppler frequency of the k-th Doppler unit, the superscript T indicates the non-conjugate transpose, and the k-1, k and k+1 Doppler units are three adjacent Doppler units.

4b)根据距离多普勒域目标回波信号的表达式(6)，构造位于第l号距离单元第k-1、k和k+1个多普勒单元的目标的空时导向矢量Dl，k：4b) According to the expression (6) of the target echo signal in the range Doppler domain, construct the space-time steering vector D l of the target located in the k-1, k and k+1 Doppler units of the l-th range unit , k :

其中，为第l号距离单元第k个多普勒单元的目标的导向矢量；为第l号距离单元第k-1个多普勒单元的目标的导向矢量；为第l号距离单元第k+1个多普勒单元的目标的导向矢量；表达式为：in, Be the steering vector of the target of the k-th Doppler cell in the l-th range cell; Be the steering vector of the target of the k-1 Doppler unit of the No. l range unit; is the steering vector of the target of the k+1 Doppler unit of the No. l range unit; The expression is:

其中，表示第k个多普勒单元的多普勒频率，λ为信号波长，va为雷达平台速度，vx为目标方位向速度，vy为目标距离向速度，d为相邻通道的等效相位中心的间距。in, Indicates the Doppler frequency of the kth Doppler unit, λ is the signal wavelength, v a is the radar platform velocity, v x is the target azimuth velocity, v y is the target range velocity, d is the equivalent of the adjacent channel The distance between phase centers.

4c)通过求解以下公式(10)求解权向量wl，k，得到 4c) Solve the weight vector w l,k by solving the following formula (10), get

其中，为第k个多普勒单元的协方差矩阵，Dl，k为第l号距离单元第k-1、k和k+1个多普勒单元的目标的空时导向矢量，表示第1通道第l号距离单元第k个多普勒单元的数据，表示第2通道第l号距离单元第k个多普勒单元的数据，表示第3通道第l号距离单元第k个多普勒单元的数据。in, is the covariance matrix of the kth Doppler unit, D l, k is the space-time steering vector of the target of the k-1, k and k+1 Doppler units of the l-th range unit, Indicates the data of the kth Doppler unit of the first channel and the No. l range unit, Indicates the data of the kth Doppler unit of the No. 1 range unit of the second channel, Indicates the data of the kth Doppler unit in the range unit l of the third channel.

在子步骤4c)中为使杂波抑制性能最优，也就是为了使输出信杂噪比最大，所以权向量wl，k要满足上述公式(10)中的约束条件。In sub-step 4c), in order to optimize the clutter suppression performance, that is, to maximize the output signal-to-noise ratio, the weight vector w l, k must satisfy the constraints in the above formula (10).

4d)利用权向量wl，k对空时数据矢量zl，k进行自适应杂波抑制：4d) Using the weight vector w l, k to perform adaptive clutter suppression on the space-time data vector z l, k :

其中，yl，k为第l号待检测距离单元第k个多普勒单元的自适应杂波抑制后的数据，wl，k为权向量，上标H表示共轭转置。Among them, y l, k are the data after adaptive clutter suppression of the kth Doppler unit of the lth distance unit to be detected, w l, k are the weight vectors, and the superscript H means conjugate transposition.

4e)令k增加1，重复步骤4a)～4d)，直至k等于K，K为需要进行目标检测的多普勒单元的个数，得到第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据：yl＝[yl，1，yl，2，…，yl，K]。4e) increase k by 1, repeat steps 4a) to 4d), until k is equal to K, K is the number of Doppler units that need to be detected, and the number of each Doppler unit of the No. 1 distance unit to be detected is obtained Data after adaptive clutter suppression: y l =[y l, 1 , y l, 2 , . . . , y l, K ].

步骤5，令待检测距离单元的数目l增加1，重复步骤2～4，直至l等于L，即完成L个距离单元杂波抑制，输出L个距离单元杂波抑制后的数据Y，Y＝[y1，y2，…yl…，yL]。Step 5: Increase the number l of range units to be detected by 1, repeat steps 2-4 until l is equal to L, that is, complete the suppression of L range unit clutter, and output the data Y after L range unit clutter suppression, Y= [y 1 , y 2 , . . . y l . . . , y L ].

下面结合仿真实验对本发明的效果做进一步说明。The effects of the present invention will be further described below in combination with simulation experiments.

仿真1，杂波抑制前的数据仿真。Simulation 1, data simulation before clutter suppression.

SAR系统仿真参数见表1，雷达工作在正侧视模式下，观测场景中存在一个运动目标，其方位向速度为零，距离向速度为10m/s。仿真结果见图3，图中给出的是杂波抑制前距离压缩后的距离多普勒域数据，也就是距离压缩之后的目标回波信号；图的像素单元的颜色表示数据的幅度，从仿真结果可以看出，目标完全被杂波淹没，如果不进行杂波抑制的话，不可能检测到目标。在本发明仿真图中的距离门为距离单元。The simulation parameters of the SAR system are shown in Table 1. The radar works in the side-view mode, and there is a moving target in the observation scene, whose azimuth velocity is zero and the range velocity is 10m/s. The simulation results are shown in Figure 3. The figure shows the range Doppler domain data after range compression before clutter suppression, that is, the target echo signal after range compression; the color of the pixel unit in the figure represents the data amplitude, from It can be seen from the simulation results that the target is completely submerged by clutter, and it is impossible to detect the target without clutter suppression. The range gate in the simulation diagram of the present invention is a range unit.

表1Table 1

载频carrier frequency 5.4GHz5.4GHz 雷达速度radar speed 7500m/s7500m/s 距离带宽distance bandwidth 50MHz50MHz 场景中心距离scene center distance 924km924km 距离采样频率Distance sampling frequency 75MHz75MHz 方位带宽Azimuth bandwidth 2000Hz2000Hz 脉冲重复频率pulse repetition frequency 3000Hz3000Hz 脉宽pulse width 20μs20μs 信噪比SNR 15dB15dB 杂噪比noise-to-noise ratio 15dB15dB 通道数number of channels 33 基线长度baseline length 2.5m2.5m

仿真2，使用本发明技术进行杂波抑制后的数据仿真。Simulation 2, using the technology of the present invention to perform data simulation after clutter suppression.

本仿真中的参数设置与仿真1相同，仿真结果见图4，图中给出的是杂波抑制后距离压缩后的距离多普勒域数据，也就是完成所有距离单元杂波抑制后的数据；图的像素单元的颜色表示数据的幅度，从仿真结果可以看出，杂波抑制后目标清晰可见，目标很容易就能被检测到，这表明本发明能很好的抑制杂波。The parameter settings in this simulation are the same as those in Simulation 1. The simulation results are shown in Figure 4. The figure shows the range Doppler domain data after clutter suppression and range compression, that is, the data after all range unit clutter suppression is completed. ; The color of the pixel unit in the figure represents the magnitude of the data. It can be seen from the simulation results that the target is clearly visible after clutter suppression, and the target can be easily detected, which shows that the present invention can suppress clutter very well.

仿真3，距离多普勒域杂波抑制效果比较。Simulation 3, comparison of clutter suppression effects in the range Doppler domain.

本仿真中的参数设置与仿真1相同，仿真结果见图5，其中实线表示的是采用DPCA技术时的杂波抑制比，‘*’线表示的是采用传统自适应杂波抑制技术时的杂波抑制比，‘+’线表示的是采用本发明时的杂波抑制比。从仿真结果可以看出，在整个多普勒带宽内，传统自适应杂波抑制技术的杂波抑制性能都要好于DPCA技术，而本发明的杂波抑制性能比DPCA技术与传统自适应杂波抑制技术都要好。The parameter settings in this simulation are the same as those in Simulation 1. The simulation results are shown in Figure 5, where the solid line represents the clutter suppression ratio when using DPCA technology, and the '*' line represents the clutter suppression ratio when using traditional adaptive clutter suppression technology The clutter suppression ratio, the '+' line represents the clutter suppression ratio when the present invention is adopted. As can be seen from the simulation results, within the entire Doppler bandwidth, the clutter suppression performance of the traditional adaptive clutter suppression technology is better than that of the DPCA technology, and the clutter suppression performance of the present invention is better than that of the DPCA technology and the traditional adaptive clutter Suppression techniques are better.

Claims (3)

1.一种星载三通道SAR-GMTI自适应杂波抑制方法，其特征在于，包括以下步骤：1. a spaceborne three-channel SAR-GMTI adaptive clutter suppression method, is characterized in that, comprises the following steps: 步骤1，建立目标原始回波信号模型，根据目标原始回波信号得到距离频率域目标回波信号；根据距离频率域目标回波信号构造距离频率域距离压缩滤波器；根据距离频率域目标回波信号和距离频率域距离压缩滤波器得到距离压缩后的距离多普勒域目标回波信号；Step 1, establish the target original echo signal model, and obtain the target echo signal in the range frequency domain according to the original target echo signal; construct the range frequency domain range compression filter according to the target echo signal in the range frequency domain; The range compression filter in the signal and range frequency domain obtains the target echo signal in the range Doppler domain after range compression; 步骤2，星载三通道SAR-GMTI系统接收三通道原始回波信号，对接收到的三通道原始回波信号分别进行距离向傅里叶变换就得到距离频率域回波信号，再根据距离频率域距离压缩滤波器对距离频率域回波信号分别进行距离压缩，得到距离压缩之后的回波信号，并将距离压缩之后的回波信号变换到距离多普勒域，得到距离压缩后的距离多普勒域回波信号；Step 2. The spaceborne three-channel SAR-GMTI system receives the three-channel original echo signal, and performs range-to-Fourier transform on the received three-channel original echo signal to obtain the range-frequency domain echo signal, and then according to the range-frequency The domain range compression filter performs range compression on the echo signals in the range frequency domain to obtain the echo signals after range compression, and transforms the echo signals after range compression into the range Doppler domain to obtain the range compression. The echo signal in the Puler domain; 步骤3，从每一通道距离压缩后的距离多普勒域回波信号中取出第l号待检测距离单元的数据xl，i，i表示通道序号，i＝1，2，3，l＝1，...，L，L为需要进行目标检测的距离单元的个数，则三个通道的第l号待检测距离单元的数据Xl表示为：Step 3, extract the data x l, i of the No. 1 range unit to be detected from the range-Doppler domain echo signal after the range compression of each channel, i represents the channel number, i=1, 2, 3, l= 1, ..., L, L is the number of distance units that need to be detected, then the data X1 of the No. l distance unit to be detected of the three channels is expressed as: Xl＝[xl，1，xl，2，xl，3]Xl = [xl , 1 , xl , 2 , xl , 3 ] 其中，xl，1为第1通道第l号距离单元的数据，xl，2为第2通道第l号距离单元的数据，xl，3为第3通道第l号距离单元的数据，xl，1、xl，2和xl，3维数均为K×1，K为需要进行目标检测的多普勒单元的个数；Wherein, x 1, 1 is the data of the No. 1 distance unit of the 1st channel, x 1, 2 is the data of the No. 1 distance unit of the 2nd channel, x 1, 3 is the data of the No. 1 distance unit of the 3rd channel, x l, 1 , x l, 2 and x l, 3 dimensions are all K×1, K is the number of Doppler units that need to detect the target; 步骤4，在三个通道的第l号待检测距离单元的数据Xl中，构建三个相邻多普勒单元的数据的空时数据矢量zl，k；再根据步骤1得到的距离压缩后的距离多普勒域目标回波信号构造三个相邻多普勒单元的目标的空时导向矢量Dl，k；根据三个相邻多普勒单元的目标的空时导向矢量Dl，k求解权向量wl，k；利用权向量wl，k对空时数据矢量zl，k进行自适应杂波抑制，得到第l号待检测距离单元第k个多普勒单元的自适应杂波抑制后的数据yl，k；再完成第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据yl＝[yl，1，yl，2，…，yl，K]T；Step 4, in the data X l of the No. l distance unit to be detected of the three channels, construct the space-time data vector z l, k of the data of three adjacent Doppler units; then compress according to the distance obtained in step 1 Construct the space-time steering vector D l, k of the target of the three adjacent Doppler units based on the echo signal of the target in the range Doppler domain; according to the space-time steering vector D l of the target of the three adjacent Doppler units , k to solve the weight vector w l, k ; use the weight vector w l, k to perform adaptive clutter suppression on the space-time data vector z l, k , and obtain the automatic Adapt to the data y l after clutter suppression, k ; then complete the data y l after adaptive clutter suppression of each Doppler unit of the No. 1 distance unit to be detected = [y l, 1 , y l, 2 , ..., y l, K ] T ; 步骤5，令待检测距离单元的数目l增加1，重复步骤2～4，直至l等于L，即完成L个距离单元杂波抑制，输出L个距离单元杂波抑制后的数据Y，Y＝[y1，y2，…yl…，yL]。Step 5: Increase the number l of range units to be detected by 1, repeat steps 2-4 until l is equal to L, that is, complete the suppression of L range unit clutter, and output the data Y after L range unit clutter suppression, Y= [y 1 , y 2 , . . . y l . . . , y L ]. 2.根据权利要求1所述的一种星载三通道SAR-GMTI自适应杂波抑制方法，其特征在于，步骤1包括以下子步骤：2. a kind of spaceborne three-channel SAR-GMTI adaptive clutter suppression method according to claim 1, is characterized in that, step 1 comprises the following substeps: 1a)目标到第i个通道的瞬时距离表示为：1a) The instantaneous distance from the target to the i-th channel is expressed as: RR ii (( tt aa )) == (( ythe y 00 ++ vv ythe y tt aa )) 22 ++ [[ vv xx tt aa -- vv aa tt aa ++ (( ii -- 11 )) dd ]] 22 -- -- -- (( 11 )) 其中，vx为目标方位向速度，vy为目标距离向速度，y0为慢时间ta＝0时目标的纵坐标，i表示通道序号，i＝1，2，3；Among them, v x is the target azimuth velocity, v y is the target range velocity, y 0 is the ordinate of the target when the slow time t a =0, i represents the channel number, i=1, 2, 3; 第i个通道接收到的目标原始回波信号表示为：The target original echo signal received by the i-th channel is expressed as: sthe s ii (( tt rr ,, tt aa )) == AA 00 ww aa (( tt aa )) ww rr (( tt rr -- 22 RR ii (( tt aa )) cc )) expexp {{ -- jj 44 πfπf cc RR ii (( tt aa )) cc ++ jπKjπK rr (( tt rr -- 22 RR ii (( tt aa )) cc )) 22 }} -- -- -- (( 22 )) 其中，A0为反映动目标散射率的复常数，tr为快时间，c为光速，wa(ta)为方位包络，wr(tr)为距离包络，fc为载频，Kr为系统发射信号的调频率，ta为慢时间，i＝1，2，3；Among them, A 0 is the complex constant reflecting the scattering rate of the moving target, t r is the fast time, c is the speed of light, w a (t a ) is the azimuth envelope, w r (t r ) is the distance envelope, f c is the load frequency, K r is the modulation frequency of the system transmitting signal, t a is the slow time, i=1, 2, 3; 1b)根据公式(2)，得到距离频率域目标回波信号，表达式为：1b) According to the formula (2), the target echo signal in the range frequency domain is obtained, the expression is: sthe s ii (( ff rr ,, tt aa )) == AA 00 ww aa (( tt aa )) WW rr (( ff rr )) expexp {{ -- jj 44 ππ (( ff rr ++ ff cc )) cc RR ii (( tt aa )) }} expexp {{ -- jj πfπf rr 22 KK rr }} -- -- -- (( 33 )) 其中，fr为距离频率，ta为慢时间，Wr(fr)为距离频率包络，fc为载频，Kr为系统发射信号的调频率，A0为反映动目标散射率的复常数，c为光速，wa(ta)为方位包络；Among them, fr is the range frequency, t a is the slow time, W r ( fr ) is the range frequency envelope, f c is the carrier frequency, K r is the modulation frequency of the system's transmitted signal, and A 0 is the scattering rate reflecting the moving target The complex constant of , c is the speed of light, w a (t a ) is the azimuth envelope; 1c)根据距离频率域目标回波信号的表达式，构造距离频率域距离压缩滤波器为：1c) According to the expression of the target echo signal in the range frequency domain, construct the range compression filter in the range frequency domain as: Hh rr (( ff rr )) == αα pp {{ jj πfπf rr 22 KK rr }} -- -- -- (( 44 )) 其中，fr为距离频率，Kr为系统发射信号的调频率；Among them, f r is the distance frequency, and K r is the modulation frequency of the signal transmitted by the system; 1d)利用距离频率域距离压缩滤波器对距离频率域目标回波信号进行距离压缩，得到距离压缩之后的目标回波信号，根据式(3)和式(2)，距离压缩之后的目标回波信号表达式为：1d) Use the distance compression filter in the range frequency domain to perform range compression on the target echo signal in the range frequency domain to obtain the target echo signal after range compression. According to formula (3) and formula (2), the target echo signal after range compression The signal expression is: sthe s ii ,, rr cc (( ff rr ,, tt aa )) == sthe s ii (( ff rr ,, tt aa )) Hh rr (( ff rr )) == AA 00 ww aa (( tt aa )) WW rr (( ff rr )) expexp {{ -- jj 44 ππ (( ff rr ++ ff cc )) cc RR ii (( tt aa )) }} -- -- -- (( 55 )) 其中，fr为距离频率，ta为慢时间，Wr(fr)为距离频率包络，fc为载频，Kr为系统发射信号的调频率，A0为反映动目标散射率的复常数，c为光速，wa(ta)为方位包络；Among them, fr is the range frequency, t a is the slow time, W r ( fr ) is the range frequency envelope, f c is the carrier frequency, K r is the modulation frequency of the system's transmitted signal, and A 0 is the scattering rate reflecting the moving target The complex constant of , c is the speed of light, w a (t a ) is the azimuth envelope; 1e)对距离压缩后的目标回波信号进行距离向逆傅里叶变换和方位向傅里叶变换，得到距离压缩后的距离多普勒域目标回波信号，距离压缩后的距离多普勒域目标回波信号的表达式为：1e) Perform range inverse Fourier transform and azimuth Fourier transform on the range-compressed target echo signal to obtain the range-compressed range-Doppler domain target echo signal, and the range-compressed range-Doppler domain The expression of domain target echo signal is: sthe s ii ,, rr cc (( tt rr ,, ff aa )) == AA 00 sinsin cc {{ BB [[ tt rr -- ythe y 00 cc (( 22 ++ λλ 22 ff aa 22 -- 44 vv ythe y 22 44 (( vv aa -- vv xx )) 22 )) ]] }} WW aa (( ff aa ++ 22 vv ythe y λλ )) expexp {{ jj πλyπλy 00 22 (( vv aa -- vv xx )) 22 (( ff aa ++ 22 vv ythe y λλ )) 22 }} ×× expexp {{ -- jj 22 ππ dd (( ii -- 11 )) vv aa -- vv xx (( ff aa ++ 22 vv ythe y λλ )) }} expexp {{ -- jj 44 ππ λλ ythe y 00 }} -- -- -- (( 66 )) 其中，tr为快时间，B为发射信号的带宽，A0为反映动目标散射率的复常数，c为光速，fa为多普勒频率，Wa(fa)为多普勒频率包络，λ为信号波长，va为雷达平台速度，vx为目标方位向速度，vy为目标距离向速度，y0为慢时间ta＝0时目标的纵坐标，d为相邻通道的等效相位中心的间距。Among them, t r is the fast time, B is the bandwidth of the transmitted signal, A 0 is the complex constant reflecting the scattering rate of the moving target, c is the speed of light, f a is the Doppler frequency, W a (f a ) is the Doppler frequency envelope, λ is the signal wavelength, v a is the velocity of the radar platform, v x is the target azimuth velocity, v y is the target range velocity, y 0 is the ordinate of the target when the slow time t a =0, d is the adjacent The distance between the equivalent phase centers of the channels. 3.根据权利要求2所述的一种星载三通道SAR-GMTI自适应杂波抑制方法，其特征在于，步骤4包括以下子步骤：3. a kind of spaceborne three-channel SAR-GMTI adaptive clutter suppression method according to claim 2, is characterized in that, step 4 comprises the following sub-steps: 4a)在三个通道的第l号待检测距离单元的数据Xl中，选择第k-1、k和k+1个多普勒单元的数据构成空时数据矢量zl，k：4a) Among the data X 1 of the No. 1 distance unit to be detected in the three channels, select the data of the k-1, k and k+1 Doppler units to form the space-time data vector z 1, k : zz ll ,, kk == [[ xx ll ,, 11 (( ff aa kk -- 11 )) ,, xx ll ,, 22 (( ff aa kk -- 11 )) ,, xx ll ,, 33 (( ff aa kk -- 11 )) ,, xx ll ,, 11 (( ff aa kk )) ,, xx ll ,, 22 (( ff aa kk )) ,, xx ll ,, 33 (( ff aa kk )) ,, xx ll ,, 11 (( ff aa kk ++ 11 )) ,, xx ll ,, 22 (( ff aa kk ++ 11 )) ,, xx ll ,, 33 (( ff aa kk ++ 11 )) ]] TT -- -- -- (( 77 )) 其中，表示第1通道第l号距离单元第k个多普勒单元的数据，表示第2通道第l号距离单元第k个多普勒单元的数据，表示第3通道第l号距离单元第k个多普勒单元的数据，表示第k个多普勒单元的多普勒频率，上标T表示非共轭转置，k-1、k和k+1个多普勒单元为三个相邻多普勒单元；in, Indicates the data of the kth Doppler unit of the first channel and the No. l range unit, Indicates the data of the kth Doppler unit of the No. 1 range unit of the second channel, Represents the data of the kth Doppler unit of the No. 1 range unit of the third channel, Indicates the Doppler frequency of the k-th Doppler unit, the superscript T indicates the non-conjugate transpose, and the k-1, k and k+1 Doppler units are three adjacent Doppler units; 4b)根据距离多普勒域目标回波信号的表达式(6)，构造位于第l号距离单元第k-1、k和k+1个多普勒单元的目标的空时导向矢量Dl，k：4b) According to the expression (6) of the target echo signal in the range Doppler domain, construct the space-time steering vector D l of the target located in the k-1, k and k+1 Doppler units of the l-th range unit , k : DD. ll ,, kk == [[ sthe s ll (( ff aa kk -- 11 )) ,, sthe s ll (( ff aa kk )) ,, sthe s ll (( ff aa kk ++ 11 )) ]] TT -- -- -- (( 88 )) 其中，为第l号距离单元第k个多普勒单元的目标的导向矢量；为第l号距离单元第k-1个多普勒单元的目标的导向矢量；为第l号距离单元第k+1个多普勒单元的目标的导向矢量；in, Be the steering vector of the target of the k-th Doppler cell in the l-th range cell; Be the steering vector of the target of the k-1 Doppler unit of the No. l range unit; is the steering vector of the target of the k+1 Doppler unit of the No. l range unit; 4c)通过求解以下公式(10)求解权向量wl，k，得到 4c) Solve the weight vector w l,k by solving the following formula (10), get 其中，为第k个多普勒单元的协方差矩阵，Dl，k为第l号距离单元第k-1、k和k+1个多普勒单元的目标的空时导向矢量，表示第1通道第l号距离单元第k个多普勒单元的数据，表示第2通道第l号距离单元第k个多普勒单元的数据，表示第3通道第l号距离单元第k个多普勒单元的数据；in, is the covariance matrix of the kth Doppler unit, D l, k is the space-time steering vector of the target of the k-1, k and k+1 Doppler units of the l-th range unit, Indicates the data of the kth Doppler unit of the first channel and the No. l range unit, Indicates the data of the kth Doppler unit of the No. 1 range unit of the second channel, Represent the data of the kth Doppler unit of the No. 1 range unit of the 3rd channel; 4d)利用权向量wl，k对空时数据矢量zl，k进行自适应杂波抑制：4d) Using the weight vector w l, k to perform adaptive clutter suppression on the space-time data vector z l, k : ythe y ll ,, kk == ww ll ,, kk Hh zz ll ,, kk -- -- -- (( 1111 )) 其中，yl，k为第l号待检测距离单元第k个多普勒单元的自适应杂波抑制后的数据，wl，k为权向量，上标H表示共轭转置；Wherein, y l, k are the data after the adaptive clutter suppression of the kth Doppler unit of the No. l distance unit to be detected, w l, k are weight vectors, and superscript H represents conjugate transposition; 4e)令k增加1，重复步骤4a)～4d)，直至k等于K，K为需要进行目标检测的多普勒单元的个数，得到第l号待检测距离单元每个多普勒单元的自适应杂波抑制后的数据：yl＝[yl，1，yl，2，…，yl，K]T。4e) increase k by 1, repeat steps 4a) to 4d), until k is equal to K, K is the number of Doppler units that need to be detected, and the number of each Doppler unit of the No. 1 distance unit to be detected is obtained Data after adaptive clutter suppression: y l =[y l, 1 , y l, 2 , . . . , y l, K ] T .
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