首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 125 毫秒
1.
该文提出一种基于Keystone-Wigner变换进行运动目标成像的快速目标参数估计方法。快速目标的径向速度会引起距离走动和方位多普勒偏移,仅根据干涉相位值无法获取准确的动目标多普勒中心,而辅以走动率信息则可以解多普勒中心模糊以得到正确的径向速度估计。动目标沿航向速度会引起方位调频率的改变,导致在常规SAR图像中动目标方位散焦,校正动目标距离走动后提取目标信号进行KWT分析,得到动目标调频率值,此时再取干涉相位求得径向速度,最后得到沿航向速度。该文在Dechirp域进行动目标检测,在提取快速目标径向速度过程中同时考虑了脉冲重复频率(PRF)模糊和干涉相位模糊,并最终实现了快速目标的准确定位和测速。实测数据处理结果验证了所提出方法的有效性。  相似文献   

2.
一种脉冲多普勒雷达解距离模糊的新算法   总被引:2,自引:0,他引:2  
脉冲多普勒雷达在信号检测时存在距离模糊和速度模糊的问题,为了解决模糊问题,在体制上雷达一般采用多重脉冲重复频率(PRF)的工作方式。对于这种体制的雷达,人们已经给出了多种解模糊算法。本文主要阐述了一种解距离模糊的新方法及其实现步骤,并给出了利用该算法解距离模糊的仿真结果。  相似文献   

3.
韩红波 《舰船电子对抗》2011,34(6):68-70,78
模糊问题是脉冲多普勒雷达在信号检测时存在的固有问题,为了解决模糊问题,雷达一般采用多重脉冲重复频率(PRF)的工作方式。对于这种体制的雷达,目前常用的解模糊算法有孙子定理方法、一维集算法和查表法。主要阐述了一种基于一维集算法的改进算法及其实现步骤,并给出了利用该算法解距离模糊的仿真结果。  相似文献   

4.
研究了一种基于频带分割的低PRF模式下的抗多普勒模糊处理方法。通过对多个通道相参积累后的结果进行合成,在保证距离不模糊的前提下,解决了速度模糊问题。仿真结果验证了算法的正确性与合理性。  相似文献   

5.
多目标的多普勒解模糊处理是低脉冲重复频率(PRF)雷达的关键技术之一,论文提出一种新的基于压缩感知(CS)理论的多普勒解模糊处理方法,利用多重PRF方式下相参处理间隔内的时域欠采样特性及多普勒频谱的稀疏特性,构造了多普勒解模糊的CS模型,采用正交匹配追踪(OMP)算法直接估计出无模糊多普勒谱的幅度响应,可实现PRF分组参差方式下对多个目标的解多普勒模糊处理,仿真结果验证了算法的有效性。  相似文献   

6.
具有纠错能力的解距离模糊的模糊数法   总被引:1,自引:0,他引:1  
戴文琪  赵问道 《电子学报》1991,19(3):127-128,F003
本文提出能进行纠错的多重PRF解模糊距离的模糊数法。用三重PRF解模糊数法具有自动纠错能力,且可检测最大距离达到三重PRF最大不模糊距离。该方法简单而易于实时处理,其测距精度与单重PRF相同。  相似文献   

7.
李斌  黄银和  吴刚  雷志勇 《电讯技术》2014,54(11):1499-1504
随机脉冲重复频率(PRI)脉冲波形能够增加电子支援措施(ESM)利用重频分选侦收雷达辐射源信号的难度,提高雷达复杂对抗环境下的抗侦收能力。利用非均匀离散傅里叶变换(NUDFT)对这种低截获概率(LPI)波形进行脉冲多普勒(PD)处理时,距离模糊引起目标所处距离门走动,导致目标能量分散至多个模糊距离单元。为此,提出一种基于时间窗口的离散傅里叶变换(TWDFT)算法,实现了距离模糊条件下目标能量的相参积累。对TWDFT算法和加权副瓣抑制的性能进行了分析。仿真结果表明,基于TWDFT的PD处理在距离模糊时不存在目标能量分散问题,通过优化波形设计能够改善加权后目标主副瓣比。  相似文献   

8.
为了解决距离模糊的问题,脉冲多普勒(PD)雷达采用多重脉冲重复频率(PRF)的工作方式,解模糊最常用的算法是中国余数定理法,但在有测量误差时,解模糊的结果误差会很大.本文阐述了基于冗余思想的一种解模糊算法,由于只计算各重视在距离与基准视在距离间的方差,使参照值相应增多,可能错解的表值组合大大减少,从而提高了目标识别的精度.  相似文献   

9.
研究了合成孔径雷达地面动目标检测(SAR-GMTI)的快速目标检测问题。为提高检测概率,在回波数据的距离压缩-方位时域,对基带多普勒中心偏移对应的速度分量引起的走动采用Keystone变换进行校正,对整数倍脉冲重复频率(PRF)的多普勒中心偏移对应速度引起的走动量则可在时域加以校正,校正后再进行方位匹配滤波得到运动目标SAR图像,同时利用距离走动信息完成速度解模糊。实测数据处理结果验证了该方法的有效性。  相似文献   

10.
优化MapDrift算法估计SAR多普勒频率   总被引:1,自引:0,他引:1  
徐如海 《现代雷达》2008,30(2):49-51
在采用MapDrift算法估计多普勒调频率时,如何选择距离单元内的方位向信号作估计将直接影响其估计的精度,传统的能量最大准则方法不能保证所选距离单元内存在单一强散射点,估计精度受限,文中采用先Dechirp脉压再做选择的方法,并且判断前半部分和后半部分信号是否包含相同的强散射点,对满足条件的方位向信号进行多普勒调频率估计,实际数据补偿效果表明了该方法的有效性。  相似文献   

11.
PRF-ambiguity resolving by wavelength diversity   总被引:8,自引:0,他引:8  
For high-precision synthetic aperture radar (SAR) processing, the determination of the Doppler centroid is indispensable. The Doppler frequency estimated from azimuth spectra, however, suffers from the fact that the data are sampled with the pulse repetition frequency (PRF) and an ambiguity about the correct PRF band remains. A novel algorithm to resolve this ambiguity is proposed. It uses the fact that the Doppler centroid depends linearly on the transmitted radar frequency for a given antenna squint angle. This dependence is not subject to PRF ambiguities. It can be measured by Fourier-transforming the SAR data in the range direction and estimating the Doppler centroid at each range frequency. The achievable accuracy is derived theoretically and verified with Seasat data of different scene content. The algorithm works best with low contrast scenes, where the conventional look correlation technique fails. It needs no iterative processing of the SAR data and causes only low computational load  相似文献   

12.
随机相位编码在多普勒天气雷达中的应用   总被引:1,自引:0,他引:1  
利用多普勒天气雷达观测中小尺度强对流天气系统时,为了避免产生速度模糊,往往需要采用比较高的重复频率,这时远距离回波就会产生折叠,且与正常回波混叠在一起,使数据质量大为下降。文中介绍了距离折叠产生的机制,阐述了使用随机相位编码退距离折叠的原理,并结合某型X波段多普勒天气雷达对该技术进行了成功的应用。实际探测结果表明,使用随机相位编码技术可以有效解决多普勒天气雷达的距离折叠问题,但也会在一定程度上使真实回波有所减弱,并消去边缘的弱回波。  相似文献   

13.
In this paper, we describe an approach for Doppler ambiguity resolution. This approach adopts the fact that unwrapped Doppler centroid is a linear function of range frequency for a given antenna squint angle. On this basis, an alternative azimuth compression method is addressed and performed in range frequency domain to accumulate target energy in the azimuth direction. The resulting trajectories behave as some straight lines with the average slope proportional to absolute Doppler centroid. This slope can be well estimated by image-contrast methods. Theoretical analysis and real measured SAR data show that the proposed approach works well in high- and relatively low-contrast scenes.  相似文献   

14.
脉冲多普勒雷达中的解模糊算法及实现   总被引:8,自引:1,他引:7  
解距离模糊和解速度模糊是中重复频率脉冲多普勒雷达中需要解决的重要问题.其算法的依据都是中国余数定理。但是.单靠中国余数定理仍无法解决距离测量和多普勒频率测量中的误差和遮挡问题。本文讨论了在测量误差和遮挡问题存在的情况下解距离模糊所采用的建表搜索法和解速度模糊所采用的各模糊度内最小方差过门限法.并将这两种算法与其他算法进行了对比。文中所提算法具有重要的工程应用价值。  相似文献   

15.
This paper concentrates on the data processing of Frequency Modulation Continuous Wave (FMCW), Synthetic Aperture Radar (SAR) in the case of wide swath and squint mode. In the mode, the Doppler centroid dramatically varies along slant range compared to conventional pulsed-SAR. This poses a challenge for system design and signal processing since a very large azimuth bandwidth would be introduced. In the paper, we accommodate the Doppler centroid variations with range by an im- proved spectral-length extension method, where a bulk range shift and updated Doppler centroid variations are introduced to greatly reduce the azimuth aliasing with respective to the existing methods Moreover, an image formation approach that integrates wave number domain algorithm is presented to focus the raw data of FMCW SAR in the case of wide swath and squint mode. Point target simulation experiment demonstrates the advantages of the presented method.  相似文献   

16.
距离—速度噪扰模糊数据同时分辨的孙子定理算法   总被引:5,自引:0,他引:5  
黄振兴  万征 《电子学报》1992,20(9):27-33
本文描述了一种推广的孙子定理,针对噪扰模糊数据发展了一种基于该定理的模糊分辨算法。该法可以同时完成中重复频率脉冲多普勒雷达的距离及速度的模糊分辨.文中还分析了该算法的正确解模糊条件及概率.  相似文献   

17.
This paper describes a complete end-to-end Doppler centroid estimation scheme, which determines the fractional PRF part of the Doppler centroid. It also resolves the Doppler ambiguity. Experiments show that the scheme works successfully over various terrain types, including land, water, and ice, and that it requires only a modest amount of SAR data to perform reliably. The proposed scheme has an added advantage that it is directly applicable to RADARSAT and ENVISAT ScanSAR data. The scheme uses two complementary Doppler estimation algorithms, both utilizing the phase information embedded in the radar signal. In each algorithm, upper and lower parts of the available bandwidth of the received signal are extracted to form two range looks. The first algorithm, called multilook cross correlation (MLCC), computes the average cross correlation coefficient between adjacent azimuth samples for each of the two looks and then takes the difference between the angles of the two coefficients. The Doppler ambiguity is determined from the angle difference. The fractional pulse repetition frequency (PRF) part is also determined from the cross correlation coefficients. In the second algorithm, called multilook beat frequency (MLBF), the two looks are multiplied together to generate a beat signal. The beat frequency is then estimated and the Doppler ambiguity determined from the beat frequency. The MLCC algorithm performs better with low contrast scenes while the MLBF works better with high contrast ones. Although each algorithm works well on its own with sufficient averaging, it is also possible to use quality measures to select the best result from either algorithm. In this way, scenes of different content or contrast can be handled reliably. This paper presents the analysis of the two algorithms, explaining why their performance is affected by scene contrast, which is confirmed by experimental results with ERS-1 and JERS-1 data  相似文献   

18.
为了解决高重频脉冲多普勒末制导雷达制导过程中的距离遮挡和距离模糊问题,实现在距离遮挡环境下正常解模糊,提出了相应的解决方法:通过对发射信号重频进行参数设计,可实现在末制导过程中除弹目相遇段以外的任意距离段抗遮挡测距,再利用测得的弹目距离信息切换PRF实现抗遮挡.仿真证明了本方法的有效性和可靠性.发射信号重频的参数设计方法可有效使各脉冲重复频率信号的遮挡区交错分布,从而消除距离遮挡对于脉冲多普勒雷达解距离模糊的影响,准确的解模糊结果又为抗距离遮挡提供了有效保证.  相似文献   

19.
In synthetic aperture radar (SAR) signal processing, the Doppler centroid estimation technique, called the "clutter-lock", is important because it is related to the signal-to-noise ratio, geometric distortion, and radiometric error of the final SAR image. Conventional algorithms have either ambiguity problems or somewhat high computational load. Using the fact that the Doppler centroid and the squint angle are directly related, we propose an ambiguity-free Doppler centroid estimation technique using Radon transform, named geometry-based Doppler estimator. The proposed algorithm is computationally efficient and shows good performance of estimating the absolute Doppler centroid.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号