分布式衛(wèi)星多相位中心SAR-GMTI技術研究
發(fā)布時間：2018-11-14 19:23
【摘要】：合成孔徑雷達（SAR）技術與地面運動目標檢測（GMTI）技術相結合，可以在獲得高分辨地面場景圖像的同時完成地面動目標的檢測及測速定位，具有重要的民用和軍用價值。相比單通道SAR系統(tǒng)，多通道SAR的優(yōu)勢在于可以利用多個方位自由度有效的抑制主瓣雜波，改善動目標的檢測性能，因而受到各國學者的廣泛關注。本文針對分布式衛(wèi)星多相位中心SAR實現(xiàn)GMTI功能，開展了關于沿航跡基線形式確定、時變混合基線預處理、與高分辨率寬測繪帶成像兼容設計、模糊雜波抑制以及對誤差穩(wěn)健的動目標參數(shù)估計等關鍵技術研究。主要內容包括： 1、分析了多通道SAR系統(tǒng)中多個相位中心之間可能存在的時空關系，以交替收發(fā)模式為例，建立了多通道動目標信號模型。通過理論推導明確了形成GMTI基線的必備條件，得到如下結論：不同時間處于不同方位的兩個相位中心之間的沿航跡基線，等于以同一時間基準對這兩個相位中心位置進行插值后得到的等效位置之間的沿航跡差。該結論為不同通道構成方式下沿航跡基線的確定提供了依據(jù)。通過對比同一系統(tǒng)采用不同天線孔徑劃分和交替收發(fā)方式下的GMTI性能，說明了合理選擇天線孔徑劃分和交替方式對提升GMTI性能的重要性。 2、提出了分布式衛(wèi)星SAR-GMTI系統(tǒng)時變、混合基線的預處理方法。針對分布式衛(wèi)星系統(tǒng)中星間基線時變導致SAR圖像對相干性下降的問題，從分布式衛(wèi)星SAR系統(tǒng)的觀測幾何構型出發(fā)，采用總體最小二乘法擬合航跡方程，并依據(jù)方程參數(shù)重構虛擬的新平行航跡。通過補償原航跡和新航跡上的觀測波程差，獲得等效的固定基線回波數(shù)據(jù)。在此基礎上，針對分布式衛(wèi)星SAR系統(tǒng)中混合基線和雷達斜視導致沿航跡基線難以精確計算的問題，推導了存在混合基線和斜視情況下沿航跡基線的計算公式，提出了基于星歷和回波數(shù)據(jù)的沿航跡基線計算方法。仿真實驗結果表明，時變基線補償后，能有效提高動目標檢測性能；用所提方法計算得到的沿航跡基線長度作為測速定位的基線參數(shù)，可以獲得高精度的測速定位結果。 3、采用方位多通道抑制多普勒模糊是實現(xiàn)高分辨率寬測繪帶（HRWS）成像的有效方式，如果這些自由度用于主瓣雜波抑制則可以實現(xiàn)GMTI功能。因此，在多通道SAR系統(tǒng)中，有望實現(xiàn)兩種模式的兼容工作。但此時GMTI性能會受到方位降采樣引起的多普勒模糊的影響。為分析這一影響，推導了存在多普勒模糊下的雜波和動目標的信號形式，給出了系統(tǒng)參數(shù)的設計考慮。結合盲速、空域模糊和動目標積累損失等因素，重點討論了在多普勒模糊情況下，脈沖重復頻率（PRF）對GMTI性能的影響，并給出了一個PRF的優(yōu)化選擇仿真示例。根據(jù)理論分析和仿真實驗結果可以得到一個選擇PRF的重要原則，，即應避免抑制模糊雜波的凹口因為空域模糊而折回至感興趣速度區(qū)間。實測數(shù)據(jù)的處理結果驗證了理論分析的正確性。 4、提出了多特征聯(lián)合挑選樣本的多通道SAR模糊雜波抑制方法。針對強弱對比明顯的非均勻場景中模糊強雜波的抑制問題，分析推導了模糊雜波的多通道導向矢量，以鄰近強陸地雜波的近岸水面區(qū)域為例，建立了SAR圖像域多通道信號模型。以模糊雜波導向的推導結果和建立的模型為依據(jù)，聯(lián)合模糊雜波的幅度/相位直方圖統(tǒng)計特性和邊緣檢測挑選訓練樣本，并采用自適應匹配濾波方法抑制雜波。仿真實驗驗證了所提方法的有效性。 5、實際處理環(huán)境中，圖像配準誤差和通道相位誤差不可避免，這將導致多通道SAR-GMTI處理時動目標徑向速度估計和定位精度下降。針對這一問題，提出了基于自適應數(shù)據(jù)重構和子空間投影的動目標徑向速度估計方法。在聯(lián)合像素信號模型下，利用抑制雜波的維納權矢量自適應重構包含動目標單元的多通道數(shù)據(jù)，再采用子空間投影算法從重構的包含動目標的單次快拍數(shù)據(jù)中估計動目標的徑向速度。仿真實驗和某機載多通道SAR-GMTI實測數(shù)據(jù)的處理結果驗證了所提方法的有效性和穩(wěn)健性。
[Abstract]:The combination of synthetic aperture radar (SAR) and ground motion target detection (GMTI) technology can be used to detect and position the ground moving target while obtaining the high-resolution ground scene image, which has important civilian and military value. Compared with the single-channel SAR system, the advantage of the multi-channel SAR is that a plurality of azimuth degrees of freedom can be used to effectively suppress the main lobe clutter and improve the detection performance of the moving target, so that the multi-channel SAR is widely concerned by the scholars of various countries. In this paper, the GMTI function is realized for the distributed satellite multi-phase center SAR, and the pre-processing of the time-varying mixed base line and the imaging compatibility with the high-resolution and wide-scale mapping tape are carried out. Research on the key technologies such as the fuzzy clutter suppression and the parameter estimation of moving target with robust error. The main contents include: 1. The time-space relationship between multiple phase centers in the multi-channel SAR system is analyzed, and the multi-channel dynamic target signal is set up in the alternate mode of transmission and reception. The necessary conditions for forming the GMTI base line are defined by the theory, and the following conclusions are obtained: along the track between two phase centers with different time in different directions baseline, equal to the edge between the equivalent positions resulting from the interpolation of the two phase center positions at the same time reference The conclusion is that the determination of the baseline of the track along the track is provided in the form of different channels. Based on the comparison of the GMTI performance of the same system with different antenna aperture and alternate receiving and receiving mode, this paper illustrates the rational choice of the antenna aperture division and the alternative way to the improvement of the GMTI performance. in that case of a distributed satellite SAR-GMTI system, a time-varying, hybrid baseline of a distributed satellite SAR-GMTI system is propose. Based on the observation geometry of the distributed satellite SAR system, the overall least square method is used to fit the track equation and the virtual is reconstructed according to the equation parameters. the new parallel track is obtained, and the equivalent fixed base is obtained by compensating the difference of the observed wave path on the original track and the new track. On the basis of this, the problem that the baseline and strabismus in the distributed satellite SAR system is difficult to calculate accurately along the track baseline is derived, and the baseline and strabismus are derived from the baseline and the strabismus. Based on the calculation formula of the ephemeris and the echo data along the track basis, The simulation results show that the dynamic target detection performance can be effectively improved after the time-varying baseline compensation, and the measured baseline length along the track is used as the baseline parameter of the speed-measuring and positioning, and the high-precision measurement can be obtained. Fast positioning results. 3. The use of directional multi-channel suppression of Doppler ambiguity is an effective way to achieve high resolution wide-scale mapping (HRWS) imaging. If these degrees of freedom are used for main lobe clutter suppression, The GMTI function is realized. Therefore, in the multi-channel SAR system, it is expected to implement two functions The compatibility of the mode is compatible. However, the GMTI performance is caused by the orientation drop sampling The influence of the Doppler ambiguity is analyzed. In order to analyze the influence, the signal form of the clutter and the moving target in the presence of the Doppler ambiguity is derived. In this paper, the influence of pulse repetition frequency (PRF) on the performance of GMTI in the case of Doppler ambiguity and the effect of pulse repetition frequency (PRF) on the performance of GMTI are discussed, and a PRF is given. According to the theoretical analysis and the simulation experiment results, an important principle to choose the PRF is obtained, that is, the notch of the fuzzy clutter should be avoided because the airspace is fuzzy and folded back to the region of interest. The processed results of the measured data are verified. Correctness of the theoretical analysis. In view of the problem of the suppression of the fuzzy strong clutter in the non-uniform scene with the strong or weak contrast, the multi-channel guide vector of the fuzzy clutter is derived, and the SA is established in the near-shore surface area of the strong land clutter. The R-image domain multi-channel signal model is based on the derived result of the fuzzy clutter guidance and the established model, and the training samples for the amplitude/ phase histogram statistics of the combined fuzzy clutter and the edge detection are selected, and the self-adapting is adopted. The filter method should be matched to suppress the clutter. The simulation experiment The validity of the proposed method is verified. 5. In the actual processing environment, the image alignment error and the channel phase error are inevitable, which will result in the multi-channel SAR-GMTI processing. In this paper, the self-adaptive data reconstruction and subspace are proposed for this problem. The invention relates to a method for estimating a moving target radial velocity of a projection, Estimation of the radial velocity of the moving target in the beat data. The simulation experiment and the processing results of the measured data of a certain airborne multi-channel SAR-GMTI
【學位授予單位】：西安電子科技大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN958
[Abstract]:The combination of synthetic aperture radar (SAR) and ground motion target detection (GMTI) technology can be used to detect and position the ground moving target while obtaining the high-resolution ground scene image, which has important civilian and military value. Compared with the single-channel SAR system, the advantage of the multi-channel SAR is that a plurality of azimuth degrees of freedom can be used to effectively suppress the main lobe clutter and improve the detection performance of the moving target, so that the multi-channel SAR is widely concerned by the scholars of various countries. In this paper, the GMTI function is realized for the distributed satellite multi-phase center SAR, and the pre-processing of the time-varying mixed base line and the imaging compatibility with the high-resolution and wide-scale mapping tape are carried out. Research on the key technologies such as the fuzzy clutter suppression and the parameter estimation of moving target with robust error. The main contents include: 1. The time-space relationship between multiple phase centers in the multi-channel SAR system is analyzed, and the multi-channel dynamic target signal is set up in the alternate mode of transmission and reception. The necessary conditions for forming the GMTI base line are defined by the theory, and the following conclusions are obtained: along the track between two phase centers with different time in different directions baseline, equal to the edge between the equivalent positions resulting from the interpolation of the two phase center positions at the same time reference The conclusion is that the determination of the baseline of the track along the track is provided in the form of different channels. Based on the comparison of the GMTI performance of the same system with different antenna aperture and alternate receiving and receiving mode, this paper illustrates the rational choice of the antenna aperture division and the alternative way to the improvement of the GMTI performance. in that case of a distributed satellite SAR-GMTI system, a time-varying, hybrid baseline of a distributed satellite SAR-GMTI system is propose. Based on the observation geometry of the distributed satellite SAR system, the overall least square method is used to fit the track equation and the virtual is reconstructed according to the equation parameters. the new parallel track is obtained, and the equivalent fixed base is obtained by compensating the difference of the observed wave path on the original track and the new track. On the basis of this, the problem that the baseline and strabismus in the distributed satellite SAR system is difficult to calculate accurately along the track baseline is derived, and the baseline and strabismus are derived from the baseline and the strabismus. Based on the calculation formula of the ephemeris and the echo data along the track basis, The simulation results show that the dynamic target detection performance can be effectively improved after the time-varying baseline compensation, and the measured baseline length along the track is used as the baseline parameter of the speed-measuring and positioning, and the high-precision measurement can be obtained. Fast positioning results. 3. The use of directional multi-channel suppression of Doppler ambiguity is an effective way to achieve high resolution wide-scale mapping (HRWS) imaging. If these degrees of freedom are used for main lobe clutter suppression, The GMTI function is realized. Therefore, in the multi-channel SAR system, it is expected to implement two functions The compatibility of the mode is compatible. However, the GMTI performance is caused by the orientation drop sampling The influence of the Doppler ambiguity is analyzed. In order to analyze the influence, the signal form of the clutter and the moving target in the presence of the Doppler ambiguity is derived. In this paper, the influence of pulse repetition frequency (PRF) on the performance of GMTI in the case of Doppler ambiguity and the effect of pulse repetition frequency (PRF) on the performance of GMTI are discussed, and a PRF is given. According to the theoretical analysis and the simulation experiment results, an important principle to choose the PRF is obtained, that is, the notch of the fuzzy clutter should be avoided because the airspace is fuzzy and folded back to the region of interest. The processed results of the measured data are verified. Correctness of the theoretical analysis. In view of the problem of the suppression of the fuzzy strong clutter in the non-uniform scene with the strong or weak contrast, the multi-channel guide vector of the fuzzy clutter is derived, and the SA is established in the near-shore surface area of the strong land clutter. The R-image domain multi-channel signal model is based on the derived result of the fuzzy clutter guidance and the established model, and the training samples for the amplitude/ phase histogram statistics of the combined fuzzy clutter and the edge detection are selected, and the self-adapting is adopted. The filter method should be matched to suppress the clutter. The simulation experiment The validity of the proposed method is verified. 5. In the actual processing environment, the image alignment error and the channel phase error are inevitable, which will result in the multi-channel SAR-GMTI processing. In this paper, the self-adaptive data reconstruction and subspace are proposed for this problem. The invention relates to a method for estimating a moving target radial velocity of a projection, Estimation of the radial velocity of the moving target in the beat data. The simulation experiment and the processing results of the measured data of a certain airborne multi-channel SAR-GMTI
【學位授予單位】：西安電子科技大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN958
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