Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal ...Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.展开更多
因高度向分辨能力缺失,地基干涉雷达应用于建筑成像时会发生严重的高度向叠掩现象。层析合成孔径雷达(Tomographic Synthetic Aperture Radar,TomoSAR)技术具备高度向分辨能力,能够实现建筑三维成像。地基层析圆弧扫描合成孔径雷达(Grou...因高度向分辨能力缺失,地基干涉雷达应用于建筑成像时会发生严重的高度向叠掩现象。层析合成孔径雷达(Tomographic Synthetic Aperture Radar,TomoSAR)技术具备高度向分辨能力,能够实现建筑三维成像。地基层析圆弧扫描合成孔径雷达(Ground-based Tomographic Arc-scanning Synthetic Aperture Radar,GB-TomoArcSAR)通过双轴转台控制天线在不同俯仰角度的水平面内进行圆周扫描来获取高度向合成孔径,实现三维层析成像。本文提出了GB-TomoArcSAR的三维点云生成方法,首先构建了适用于高度向弧形采样条件的层析成像几何模型。其次利用基于巴特沃斯滤波器的奇异值分解(Singular Value Decomposition,SVD)方法进行谱估计,找出层析谱中的峰值及其对应的峰值位置,构成层析向目标候选集。随后利用自对消顺序广义似然比(Sequential Generalized Likelihood Ratio Test with Cancellation,SGLRTC)检测器估计散射体的数目与位置,通过设置检测门限将真实目标的峰值及对应的峰值位置从候选集中筛选出来。最后采用基于空间几何分布的点云优化方法剔除误差点,生成点云图像。文章通过点目标和面目标的仿真实验,验证了所提方法适用于GB-TomoArcSAR,能够有效解决高度向多散射体目标的叠掩问题;进一步开展了实测数据验证,基于所提方法获取了北京市一处建筑基坑的层析点云,其与实际场景几何特征一致。展开更多
After a brief recall of the Sidelobe Canceler (SLC) working principle, including the derivation of a general formula for the Cancellation Ratio (CR), the effects of channel mismatching are investigated. In particular,...After a brief recall of the Sidelobe Canceler (SLC) working principle, including the derivation of a general formula for the Cancellation Ratio (CR), the effects of channel mismatching are investigated. In particular, curves providing CRvalues as a function of amplitude and phase channel mismatching, radar bandwidth, and jammer direction of arrival (JDOA) are provided for the cases of one and two auxiliary antennas. Subsequently, a time -space processor for performance restoration is analyzed in detail. In addition to the above mentioned quantities, the attainable CR value is expressed as a function of the space-time processor parameters. The contribution of the paper is related to the derivation of a number of mathematical equations of CR for several cases of practical interest for the radar engineer. In addition, several curves are presented to assist design of SLC systems.展开更多
逐次逼近寄存器模数转换器(SAR ADC)在逐次逼近的过程中,电容的切换会使参考电压上出现参考纹波噪声,该噪声会影响比较器的判定,进而输出错误的比较结果。针对该问题,基于CMOS 0.5μm工艺,设计了一种具有纹波消除技术的10 bit SAR ADC...逐次逼近寄存器模数转换器(SAR ADC)在逐次逼近的过程中,电容的切换会使参考电压上出现参考纹波噪声,该噪声会影响比较器的判定,进而输出错误的比较结果。针对该问题,基于CMOS 0.5μm工艺,设计了一种具有纹波消除技术的10 bit SAR ADC。通过增加纹波至比较器输入端的额外路径,将参考纹波满摆幅输入至比较器中;同时设计了消除数模转换器(DAC)模块,对参考纹波进行采样和输入,通过反转纹波噪声的极性,消除参考纹波对ADC输出的影响。该设计将信噪比(SNR)提高到56.75 dB,将有效位数(ENOB)提升到9.14 bit,将积分非线性(INL)从-1~5 LSB降低到-0.2~0.3 LSB,将微分非线性(DNL)从-3~4 LSB降低到-0.5~0.5 LSB。展开更多
该文针对单路延迟对消系统不能有效解决多径信道的超短波无线电台共址干扰消除问题,给出了等间隔多路延迟正交合成的射频干扰对消方案,进而提出了新的衰减系数求解方法。在设定时间延迟范围和参考信号路数基础上,该方法通过迭代加权实...该文针对单路延迟对消系统不能有效解决多径信道的超短波无线电台共址干扰消除问题,给出了等间隔多路延迟正交合成的射频干扰对消方案,进而提出了新的衰减系数求解方法。在设定时间延迟范围和参考信号路数基础上,该方法通过迭代加权实时有效估计多路参考信号的相关矩阵,接收信号与参考信号的相关向量,进而求解维纳霍夫方程得到各路衰减系数,有效抑制多径信道的自干扰,克服了已有方法需同时调节幅度和相位,以及相关向量和相关矩阵估计精度低的不足。另外,理论分析了衰减系数的求解过程,并推导了自干扰对消比的闭合表达式。分析和仿真结果表明,该方法在一定延迟误差情况下,可获得90 d B以上的对消比,比已有方法提高了约9 d B,有效解决了多径信道的射频干扰对消问题。展开更多
首先,提出了一种基于自动增益控制(automatic gain control,AGC)技术的自适应干扰对消系统,并对该对消系统进行了建模与理论分析;然后,研究了AGC对消系统的收敛时间、干扰对消比和有用信号损耗特性,并分析了零漂对系统性能的影响。分析...首先,提出了一种基于自动增益控制(automatic gain control,AGC)技术的自适应干扰对消系统,并对该对消系统进行了建模与理论分析;然后,研究了AGC对消系统的收敛时间、干扰对消比和有用信号损耗特性,并分析了零漂对系统性能的影响。分析结果表明:使用该对消系统可有效降低零漂对系统性能的影响;在干扰信号功率较小时,也可得到较高的干扰对消比和较快的收敛速度。实验结果也验证了理论分析的正确性和AGC技术的有效性。展开更多
文摘Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.
文摘因高度向分辨能力缺失,地基干涉雷达应用于建筑成像时会发生严重的高度向叠掩现象。层析合成孔径雷达(Tomographic Synthetic Aperture Radar,TomoSAR)技术具备高度向分辨能力,能够实现建筑三维成像。地基层析圆弧扫描合成孔径雷达(Ground-based Tomographic Arc-scanning Synthetic Aperture Radar,GB-TomoArcSAR)通过双轴转台控制天线在不同俯仰角度的水平面内进行圆周扫描来获取高度向合成孔径,实现三维层析成像。本文提出了GB-TomoArcSAR的三维点云生成方法,首先构建了适用于高度向弧形采样条件的层析成像几何模型。其次利用基于巴特沃斯滤波器的奇异值分解(Singular Value Decomposition,SVD)方法进行谱估计,找出层析谱中的峰值及其对应的峰值位置,构成层析向目标候选集。随后利用自对消顺序广义似然比(Sequential Generalized Likelihood Ratio Test with Cancellation,SGLRTC)检测器估计散射体的数目与位置,通过设置检测门限将真实目标的峰值及对应的峰值位置从候选集中筛选出来。最后采用基于空间几何分布的点云优化方法剔除误差点,生成点云图像。文章通过点目标和面目标的仿真实验,验证了所提方法适用于GB-TomoArcSAR,能够有效解决高度向多散射体目标的叠掩问题;进一步开展了实测数据验证,基于所提方法获取了北京市一处建筑基坑的层析点云,其与实际场景几何特征一致。
文摘After a brief recall of the Sidelobe Canceler (SLC) working principle, including the derivation of a general formula for the Cancellation Ratio (CR), the effects of channel mismatching are investigated. In particular, curves providing CRvalues as a function of amplitude and phase channel mismatching, radar bandwidth, and jammer direction of arrival (JDOA) are provided for the cases of one and two auxiliary antennas. Subsequently, a time -space processor for performance restoration is analyzed in detail. In addition to the above mentioned quantities, the attainable CR value is expressed as a function of the space-time processor parameters. The contribution of the paper is related to the derivation of a number of mathematical equations of CR for several cases of practical interest for the radar engineer. In addition, several curves are presented to assist design of SLC systems.
文摘该文针对单路延迟对消系统不能有效解决多径信道的超短波无线电台共址干扰消除问题,给出了等间隔多路延迟正交合成的射频干扰对消方案,进而提出了新的衰减系数求解方法。在设定时间延迟范围和参考信号路数基础上,该方法通过迭代加权实时有效估计多路参考信号的相关矩阵,接收信号与参考信号的相关向量,进而求解维纳霍夫方程得到各路衰减系数,有效抑制多径信道的自干扰,克服了已有方法需同时调节幅度和相位,以及相关向量和相关矩阵估计精度低的不足。另外,理论分析了衰减系数的求解过程,并推导了自干扰对消比的闭合表达式。分析和仿真结果表明,该方法在一定延迟误差情况下,可获得90 d B以上的对消比,比已有方法提高了约9 d B,有效解决了多径信道的射频干扰对消问题。
文摘首先,提出了一种基于自动增益控制(automatic gain control,AGC)技术的自适应干扰对消系统,并对该对消系统进行了建模与理论分析;然后,研究了AGC对消系统的收敛时间、干扰对消比和有用信号损耗特性,并分析了零漂对系统性能的影响。分析结果表明:使用该对消系统可有效降低零漂对系统性能的影响;在干扰信号功率较小时,也可得到较高的干扰对消比和较快的收敛速度。实验结果也验证了理论分析的正确性和AGC技术的有效性。
