IMAGING ANALYSIS OF FREQUENCY MODULATION CONTINUOUS WAVE SYNTHETIC APERTURE RADAR IN NEAR RANGE MODE简

Frequency-Modulation Continuous-Wave Synthetic Aperture Radar （FMCW SAR） has shown great potential in the applications of civil and military fields because of its easy deployment and low cost. However, most of these work and analysis are concentrated on airborne FMCW SAR, where the characteristics of the ilnaging geometry and signal are much similar to that of traditional pulsed-SAR. As a result, a series of test campaigns of automobile-based FMCW SAR were sponsored by Institute of Electronics, Chinese Academy of Sciences （IECAS） in the autumn of 2012. In this paper, we analyze the imaging issues of FMCW SAR in automobile mode （named as near range mode）, where a vehicle is used as moving platform and a large looking angle is configured. The imaging geometry and signal properties are analyzed in detail. We emphasize the difference of the near range mode from the traditional airborne SAR mode. Based on the analysis, a focusing approach is proposed in the paper to handle the data focusing in the case. Simulation experiment and real data of automobile FMCW SAR are used to validate the analysis.     

EFFICIENT STRIP-MODE SAR RAW SIGNAL SIMULATION OF MIXED TARGETS BASED ON ACCURATE 2-D SPECTRUM简

An accurate and efficient Synthetic Aperture Radar （SAR） raw data generator is of con- siderable value for testing system parameters and verifying imaging algorithms. Nevertheless, the ex- isting simulator cannot exactly handle the case of the fast moving targets in high squint geometry. As for the issue, the analytical expression for the two Dimensional （2-D） signal spectrum of moving targets is derived and a fast raw echo simulation method is proposed in this study. The proposed simulator can accommodate the moving targets in tile high squint geometry, whose processing steps of the simulation are given in detail and its computational complexity is analyzed. The simulation data for static and moving targets are processed and analyzed, and the results are given to validate the effectiveness of the proposed approach.     

UWB TEM HORN ANTENNA FOR THE ASPHALT PAVEMENT INVESTIGATION简

A simple Ultra-WideBand （UWB） exponentially-tapered Transverse ElectroMagnetic （TEM） horn antenna is presented for the asphalt detection based on Ground Penetrating Radar （GPR） In order to reduce the reflections from the antenna aperture, some absorbing material is loaded on the outer surface of the conductor. Comparing with the traditional TEM horn antenna, the proposed antenna has a small size and a large impedance bandwidth. Simulated and measured results show that the proposed TEM horn antenna has a low Voltage Standing Wave Ratio （VSWR） below 2 over the whole band from 0.35 GHz to 12 GHz, good radiation characteristics, and small late-time ringing, which can perfectly meet the requirements of the GPR application.     

OMP-BASED MULTI-BAND SIGNAL RECONSTRUCTION FOR ECOLOGICAL SOUNDS RECOGNITION简

The paper proposes a new method of multi-band signal reconstruction based on Orthogonal Matching Pursuit （OMP）, which aims to develop a robust Ecological Sounds Recognition （ESR） system Firstly, the OMP is employed to sparsely decompose the original signal, thus the high correlation components are retained to reconstruct in the first stage. Then, according to the frequency distribution of both foreground sound and background noise, the signal can be compensated by the residual components in the second stage. Via the two-stage reconstruction, high non-stationary noises are ef- fectively reduced, and the reconstruction precision of foreground sound is improved. At recognition stage, we employ deep belief networks to model the composite feature sets extracted from reconstructed signal. The experimental results show that the proposed approach achieved superior recognition per- formance on 60 classes of ecological sounds in different environments under different Signal-to-Noise Ratio （SNR）, compared with the existing method.     

4G业务发展关键要素与策略研究简

随着通信市场开放力度加大，通信运营商之间的竞争将目趋激烈。为此，在4G牌照即将发放之际，探索4G发展的关键要素，拟定有效的发展策略对通信运营商具有显著的意义。论文结合文献分析、技术分析与市场分析，提取了4G发展的关键要素，梳理了其逻辑关系，并通过价值权衡，形成了对应的发展策略建议。     

NEW APPROACH TO EMULATE SEU FAULTS ON SRAM BASED FPGAS简

Field Programmable Gate Arrays （FPGAs） offer high capability in implementing of com- plex systems, and currently are an attractive solution for space system electronics. However, FPGAs are susceptible to radiation induced Single-Event Upsets （SEUs）. To insure reliable operation of FPGA based systems in a harsh radiation environment, various SEU mitigation techniques have been provided In this paper we propose a system based on dynamic partial reconfiguration capability of the modern devices to evaluate the SEU fault effect in FPGA. The proposed approach combines the fault injection controller with the host FPGA, and therefore the hardware complexity is minimized. All of the SEU injection and evaluation requirements are performed by a soft-core which realized inside the host FPGA Experimental results on some standard benchmark circuits reveal that the proposed system is able to speed up the fault injection campaign 50 times in compared to conventional method.     

35kV变电站供电系统的消谐措施简

本文介绍了35kV变电站供电系统中谐波所造成的危害,从原理上对谐波产生的原因进行了分析,并通过对变电站中实际谐波的测试和现场分析,提出了相应的消谐措施。     

DEVELOPMENT OF NEW PILL-BOX WINDOW FOR S-BAND HIGH POWER KLYSTRON简

In this paper, a new pill-box window with arc groove disk is studied for S-band high power klystron. Its main characteristics are long pill-box and periodic grooved window disk. The long pill-box window can decrease the normal field and relieve the radio frequency loss in high power transmission, and periodic grooved window disk can suppress tangential field multipactor. The Monte Carlo （MC） method is used to build up the simulation model and analyze the increasing tendency of electrons. The simulation results indicate that long-box window with periodic are grooved window disk can restrain multipactor effectively. Homocentric circular half-camber arc slot is put forward to overcome the disadvantages of periodic straight triangle and strait rectangular. The long pill-box with groove disk window prototype is tested in high power Travelling Wave Resonant Ring （TWRR） and the experi- mental results show an excellent character of this window.     

High-resolution automobile FMCW SAR and signal processing

The paper presents a high-resolution automobile Frequency Modulation Continuous Wave Synthetic Aperture Radar （FMCW SAR） named MiniSAR and the procedure of its signal processing. The imaging geometry of automobile SAR is very different from that of airborne SAR, leading to a different data processing method for automobile SAR. Therefore, in the paper, we propose an image formation approach that can well handle the focusing issues of automobile SAR. The effects of the strong reflected signal and the spatial-variant synthetic aperture length are analyzed. The processed results with automobile FMCW SAR read data validate the presented method.     

调频连续波SAR非线性处理方法研究

合成孔径雷达系统畸变引入的幅相误差严重影响了雷达的成像效果,必须予以校正才能获得高质量的图像。该文针对调频连续波SAR系统频率响应非理想特性引入的幅相误差以及信号扫频非线性误差对系统性能的影响,分析建立了存在系统误差的调频连续波SAR系统回波信号模型,研究了系统误差估计与校正的问题,并考虑小型化调频连续波SAR实时成像处理的需求,提出了一种改进的适合实时成像处理的调频连续波SAR的高精度非线性距离-多普勒成像处理算法。最后,通过理论推导和仿真分析,验证了算法的可行性和有效性。     

调频连续波SAR信号分析与成像研究

镇对调频连续波SAR与脉冲式SAR工作体制的不同,从而带来不同的回波表现形式,该文对调频连续波SAR回波信号进行了建模,分析了信号的特征,揭示了平台的连续运动在距离向产生一个多普勒频移的特性,将去斜接收体制固有的残余视频相位分离成卷积的形式,并在频域完成补偿,给出了适宜于连续波SAR成像处理的改进频率变标算法,相对于原有的频率变标算法,几乎没有增加额外的运算量。最后通过点目标仿真验证了该文分析的正确性和所提算法的有效性。     

基于精确二维频谱的调频连续波SAR动目标特性分析

传统的调频连续波(FMCW)SAR运动目标特性的分析方法大都在时域展开,导致其对目标的特性研究存在近似或者不全面。基于此,该文提出一种基于精确2维频谱模型的FMCW SAR动目标特性分析方法。该方法充分考虑了天线平台及运动目标在脉冲收发期间运动的影响,推导了解析的FMCW SAR运动目标斜距模型,进而求解了非停-走模型下的运动目标的2维频谱模型。基于该模型该文系统地分析了动目标的成像特性,精确定量地研究了动目标2维速度的影响。相对于传统时域分析方法,该方法更加精确全面而且有着更好的适应性。仿真实验验证该文分析中结论的合理性和有效性。     

调频连续波SAR概述及其发展趋势

调频连续波(FMCW)SAR是一种新近提出的成像雷达体制,它结合调频连续波与合成孔径成像技术,具有体积小、重量轻、成本低、功耗低、分辨率高、截获概率低等一系列优点。文章归纳了目前FMCWSAR的几种应用背景及其主要参数,并根据FMCW SAR的发展概况,讨论了其进一步的发展趋势。     

弹载调频连续波合成孔径雷达大斜视成像方法研究

弹载调频连续波合成孔径雷达(Frequency Modulated Continuous Wave Synthetic Aperture Radar,FMCW SAR)在大斜视工作模式下,导弹的连续运动会在距离向产生多普勒频移,导致距离向频谱偏移及方位像散焦,高速运动及大斜视角还会引入一个二次相位误差,影响距离像的聚焦.通过推导分析弹载FMCW SAR大斜视回波信号的波数域表达式,提出一种弹载FMCW SAR大斜视成像方法,在二维波数域完成了多普勒频移校正、二次相位误差补偿和距离徙动校正,很好地改善了成像质量.仿真实验验证了理论分析结果及所提成像方法的有效性.     

基于积累孔径插值技术的星载间断调频连续波SAR成像方法

间断调频连续波(IFMCW)合成孔径雷达(SAR)模式通过在不同时间间隔内交替发射和接收信号,解决了星载调频连续波(FMCW)SAR必须收发分置的问题。然而,在该模式下,雷达天线会间歇性地工作于发射和接收状态,从而导致回波数据中出现周期性的空缺。为了解决上述问题,该文提出了一种基于积累孔径插值技术的缺失数据迭代自适应成像处理方法(MIAA-AAIT),用于恢复缺失的数据。实验结果表明,所提方法可以有效地恢复缺失数据,从而显著提高成像质量,大幅降低由周期性数据缺失引起的虚假目标能量。     

检测SAR图像中径向慢速动目标

该文提出了一种从SAR图像中检测径向匀速动目标的方法,将SAR图像信号在频域分为正频部分和负频部分,静止背景的正负频分布对称,而径向动目标的多普勒质心与静止背景相比有一频移,信号在正负频域能量分布不对称。将分开的正负频域信号分别回到时域成像,计算这两幅复图像对应位置的模差绝对值,可对消静止背景,突显出径向动目标。仿真数据表明本算法有效。     

一种高效精确的FMCW SAR动静目标混合场景回波模拟方法

近几年来,由于小型无人机的兴起,基于FMCW体制的合成孔径雷达(SAR)由于体积小,重量轻,成本低得到了快速发展。然而,由于传统的脉冲SAR中的停-走假设不再成立,FMCW SAR成像处理与传统的脉冲SAR有着很大的不同,这样使得在FMCW SAR实测数据进行处理和分析时往往缺乏理论支撑。因此,开展FMCW SAR的信号处理研究具有重要的现实意义和军事价值。目前,国内外关于FMCW SAR的研究主要集中在其成像处理方法上,在回波模拟方向研究甚少,特别是对于既包含分布式运动目标又有静止目标下的真实场景下的FMCW SAR回波快速模拟方法更是鲜有涉及。基于此,该文在FMCW SAR平台脉内连续运动的基础上推导了一种适用于动静目标的精确的FMCW SAR 2维频域模型,并基于该模型提出一种高效精确的FMCW SAR动静目标混合场景回波模拟的方法。点目标和场景目标的仿真试验验证了该模拟方法的有效性,效率分析发现该种模拟方法的效率远高于传统的仿真方法。