Application of equalization notch to improve synthetic aperture radar coherent data products
Application of equalization notch to improve synthetic aperture radar coherent data products
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DOI：
10.1117/12.2175587
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发表时间：
2015-04
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影响因子：
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通讯作者：
Cameron H. Musgrove;J. West
中科院分区：
文献类型：
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作者：
Cameron H. Musgrove;J. West
干扰和干扰抑制技术降低了合成孔径雷达（SAR）相干数据产品。利用拉伸处理的雷达对许多缓解技术提出了独特的挑战，因为干扰信号本身通过拉伸处理从其原始信号特性被修改。许多干扰源（包括恒定音调）仅存在于有限数量样本的快速样本数据中，具体取决于雷达和干扰带宽。依赖于假设平稳干扰信号特性来估计和去除干扰信号的自适应滤波算法可能是无效的。一种有效的缓解方法，称为陷波，迫使包含干扰的数据样本的值为零。然而，随着被设置为零的数据样本的数量增加，图像失真和分辨率损失使图像产品和任何二阶图像产品都降级。修复图像失真的技术，1是有效的点状目标。然而，这些技术并没有被设计用于建模和修复SAR图像地形中的失真。由于地形占据了许多场景的大部分，因此良好的地形一致性对于SAR二阶图像产品非常重要。对于相干变化检测的情况，是地形相干性本身确定变化检测图像的质量。本文提出了一种独特的均衡技术，提高了现有的陷波技术的一致性。首先，与自适应滤波算法不同，所提出的算法将缓解限制为仅包含干扰的样本，因此不修改剩余样本。此外，缓解措施还适应不断变化的干扰功率，以便最终的校正使数据样本之间的功率均衡。其结果是减少了地形的失真并提高了一致性。SAR数据表明，改进的相干性，从建议的均衡校正现有的陷波方法啁啾干扰源。
Interference and interference mitigation techniques degrade synthetic aperture radar (SAR) coherent data products. Radars utilizing stretch processing present a unique challenge for many mitigation techniques because the interference signal itself is modified through stretch processing from its original signal characteristics. Many sources of interference, including constant tones, are only present within the fast-time sample data for a limited number of samples, depending on the radar and interference bandwidth. Adaptive filtering algorithms to estimate and remove the interference signal that rely upon assuming stationary interference signal characteristics can be ineffective. An effective mitigation method, called notching, forces the value of the data samples containing interference to zero. However, as the number of data samples set to zero increases, image distortion and loss of resolution degrade both the image product and any second order image products. Techniques to repair image distortions,1 are effective for point-like targets. However, these techniques are not designed to model and repair distortions in SAR image terrain. Good terrain coherence is important for SAR second order image products because terrain occupies the majority of many scenes. For the case of coherent change detection it is the terrain coherence itself that determines the quality of the change detection image. This paper proposes an unique equalization technique that improves coherence over existing notching techniques. First, the proposed algorithm limits mitigation to only the samples containing interference, unlike adaptive filtering algorithms, so the remaining samples are not modified. Additionally, the mitigation adapts to changing interference power such that the resulting correction equalizes the power across the data samples. The result is reduced distortion and improved coherence for the terrain. SAR data demonstrates improved coherence from the proposed equalization correction over existing notching methods for chirped interference sources.