WIDE SWATH FMCW SAR DATA PROCESSING IN SQUINT MODE简

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.     

Downward looking sparse linear array 3D SAR imaging algorithm based on back-projection and convex optimization

Downward Looking Sparse Linear Array Three Dimensional SAR （DLSLA 3D SAR） is an important form of 3D SAR imaging,which has a widespread application field.Since its practical equivalent phase centers are usually distributed sparsely and nonuniformly,traditional 3D SAR algorithms suffer from low resolution and high sidelobes in cross-track dimension.To deal with this problem,this paper introduces a method based on back-projection and convex optimization to achieve 3D high accuracy imaging reconstruction.Compared with traditional SAR algorithms,the proposed method sufficiently utilizes the sparsity of the 3D SAR imaging scene and can achieve lower sidelobes and higher resolution in cross-track dimension.In the simulated experiments,the reconstructed results of both simple and complex imaging scene verify that the proposed method outperforms 3D back-projection algorithm and shows satisfying cross-track dimensional resolution and good robustness to noise.     

遥感图像建筑物识别及变化检测方法

针对单独使用像素级变化检测或特征级变化检测对于高层建筑物检测精度低的问题,提出了一种图像特征和经验知识结合的建筑物识别及变化检测方法,用于检测多时相遥感图像中高层建筑物的变化情况.首先采用本文提出的Ratio梯度与交叉累积剩余熵相结合的配准算法配准两个不同时相的SAR和全色图像,分别利用知识规则识别SAR和全色图像建筑物区域,在识别的建筑物区域上,采用像素比值法进行建筑物变化检测.实验结果表明,该方法可以有效提高建筑物的检测正确率,降低虚检率和漏检率.     

A Novel Wavenumber Domain SAR Imaging Algorithm Based on the Fractional Fourier Transform

The conventional Wavenumber domain algorithm （WDA） employs Fast Fourier transform （FFT） to implement matched filter. It is characterized by its high precision SAR imaging. Compared with FFT, Fractional Fourier transform （FrFT） can provide lower and narrower sidelobes when it is applied to compress chirp signals at the optimal transform. This paper proposed a novel SAR imaging algorithm, termed FrWDA which replaces FFT in WDA with FrFT. The FrWDA was derived and its implementation was presented. How to choose the optimal transformation order was given subsequently. The FrWDA preserves high precision focusing, and has better performance on sidelobe suppression. The FrWDA is more suitable for the high precision SAR imaging, especially in target detection and recognition. Simulation results demonstrate that FrWDA provides better performance on focusing and sidelobe suppression compared with the classical FFT-based WDA.     

Analysis and Design of Multi-aspect SAR System for Compressive Sensing-Based 3D Imaging

This paper focuses on the analysis and design of Multl-aspect SAR （MuSAR） system for Compressive sensing-based （CS-based） 3D imaging. For this purpose,the Point ambiguous function （PAF） is proposed to analyze the factors that dominate the Mutual coherence （MC） of MuSAR sensing matrix. The PAF contacts with the parameters and configuration of MuSAR system directly and is easy to manipulate. With PAF, the present study analyzes the factors that dominate the performance of CS-based MuSAR 3D imaging. First of all, the stochastic waveform is an excellent selection. Second, the angular-frequency-diversity can improve the robustness of 3D imaging. Finally, the finer sampling of received data could improve the robustness of MuSAR 3D imaging. Simulation experiments show the validity of conclusion.     

一个单通道10位160兆每秒的逐次逼近式模数转换器

This paper demonstrates a single-channel 10-bit 160 MS/s successive-approximation-register （SAR） analog-to-digital converter （ADC） in 65 nm CMOS process with a 1.2 V supply voltage. To achieve high speed, a new window-opening logic based on the asynchronous SAR algorithm is proposed to minimize the logic delay, and a partial set-and-down DAC with binary redundancy bits is presented to reduce the dynamic comparator offset and accelerate the DAC settling. Besides, a new bootstrapped switch with a pre-charge phase is adopted in the track and hold circuits to increase speed and reduce area. The presented ADC achieves 52.9 dB signal-to-noise distortion ratio and 65 dB spurious-free dynamic range measured with a 30 MHz input signal at 160 MHz clock. The power consumption is 9.5 mW and a core die area of 250 ×200 μm^2 is occupied.     

SAR压制式干扰仿真及效果评估

成孔径雷达(Synthetic Aperture Radar)是一种高性能成像雷达．文中介绍了几种针对SAR的噪声压制干扰方法，并对其进行了计算机仿真，最后采用两种评估方法对仿真结果进行对比分析，结果表明，对SAR采用射频噪声压制干扰是一种较好的干扰模式。     

使用去调频宽带LFM信号的SAR实时成像处理

本文阐述了对采用去调频宽带LFM信号方法的SAR条带模式数据进行高分辨率实时成像的处理算法.与以前的实时处理不同之处在于:(1)距离向目标的回波信号经过了去调频处理;(2)要对距离单元迁移实时校正;(3)方位向单孔径实时连续成像.本文详细讨论了对SAR距离向去调频数据处理的原理和方法,提出适合实时处理的距离迁移校正的方法,并分析了整个实时处理流程的时限和计算量.实践证明本文的实时处理算法和流程是有效的.     

噪声消除算法在干涉SAR相位解缠中的应用研究

本文把噪声消除算法应用在干涉SAR相位解缠中,分析了该算法的特点.为了更好地解缠干涉SAR数据,提出了一种改进的方法.在原有两点规则的基础上,提出了三点规则,并提出把两点规则和三点规则结合使用来提高相位解缠稳健性的混合算法.该方法有效地解决了噪声消除算法在解缠质量差干涉相位图时不收敛的问题,在保持了算法的计算精度的同时提高了算法的稳健性.对仿真和真实干涉SAR数据的实验结果验证了本文方法的有效性.