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宽带运动目标回波的多普勒特性模拟方法 被引量:2
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作者 何纬婧 潘明海 《雷达科学与技术》 北大核心 2021年第4期403-408,416,共7页
宽带雷达系统测试和性能评估中目标信息模拟精度和分辨率要求很高。针对宽带线性调频雷达运动目标的回波脉冲内多普勒频率呈现线性调频(LFM)变化特征、回波脉冲之间具有时移分布和相位相干特性的问题,采用基于数字射频存储(DRFM)系统的... 宽带雷达系统测试和性能评估中目标信息模拟精度和分辨率要求很高。针对宽带线性调频雷达运动目标的回波脉冲内多普勒频率呈现线性调频(LFM)变化特征、回波脉冲之间具有时移分布和相位相干特性的问题,采用基于数字射频存储(DRFM)系统的回波脉冲内LFM多普勒频率调制、多回波相参脉冲信号之间时移模拟的方法。探讨了基于宽带DRFM系统的高精度和高分辨率的运动目标多普勒频率信息实时模拟方法。采用仿真分析和实验验证方法,证实算法性能,运动目标的多普勒频率模拟精度/分辨率在特定条件下可达到Hz级。 展开更多
关键词 宽带雷达回波重构 实时计算 脉内多普勒频率特性 间时移分布 高精度
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联合脉压与Radon傅里叶变换的长时间相参积累方法 被引量:5
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作者 裴家正 黄勇 +3 位作者 陈宝欣 关键 蔡咪 陈小龙 《雷达学报(中英文)》 CSCD 北大核心 2021年第6期956-969,共14页
传统相干雷达信号处理流程中先脉冲压缩再相参处理的级联处理在理论上无法实现对高速目标回波能量的最大化积累,级联处理的输出结果中目标峰值位置存在偏差,甚至还伴随主瓣展宽、增益下降、旁瓣增高的问题。为此该文提出一种联合脉压与R... 传统相干雷达信号处理流程中先脉冲压缩再相参处理的级联处理在理论上无法实现对高速目标回波能量的最大化积累,级联处理的输出结果中目标峰值位置存在偏差,甚至还伴随主瓣展宽、增益下降、旁瓣增高的问题。为此该文提出一种联合脉压与Radon傅里叶变换(PC-RFT)的长时间相参积累方法,利用信号之间的相关关系将匹配滤波与Radon傅里叶变换相结合,在快时间(脉内时间)与慢时间(脉间时间)维度上同时补偿脉内和脉间的多普勒频移,从而实现目标增益的最大化。实验表明二维联合处理的性能明显优于级联处理。 展开更多
关键词 冲压缩 Radon傅里叶变换 长时间相参积累 脉内多普勒频率 二维联合处理
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一种逆合成孔径激光雷达成像算法 被引量:2
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作者 杨小优 池龙 +2 位作者 何劲 雷强 张群 《激光与红外》 CAS CSCD 北大核心 2010年第8期904-909,共6页
逆合成孔径激光雷达是一种能实现对运动目标超高分辨实时成像的主动式有源成像雷达。该雷达系统发射的激光信号具有超高频率和超大带宽的特点,因此,微波波段逆合成孔径雷达针对常规目标所采用的回波信号模型不再适用。针对这一问题,给... 逆合成孔径激光雷达是一种能实现对运动目标超高分辨实时成像的主动式有源成像雷达。该雷达系统发射的激光信号具有超高频率和超大带宽的特点,因此,微波波段逆合成孔径雷达针对常规目标所采用的回波信号模型不再适用。针对这一问题,给出了适用于逆合成孔径激光雷达的运动目标回波信号模型,分析了激光信号的超高频率带来的脉内多普勒效应,利用基于参考点的运动补偿方法,在匹配滤波处理后通过包络对齐实现对运动参考点轨迹的精确估计,最终获得了精确的参考信号,实现了对运动目标的超高分辨二维成像。仿真结果验证了该算法的有效性。 展开更多
关键词 逆合成孔径激光雷达 回波信号模型 运动补偿 脉内多普勒
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宽带双基地雷达高速多目标检测方法 被引量:2
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作者 张娟 丁彤 +1 位作者 张林让 张政和 《雷达科学与技术》 北大核心 2021年第5期526-533,共8页
本文提出一种宽带双基地雷达高速多目标检测算法。针对目标高速运动产生的尺度因子和脉内多普勒,本文设计出一种新的匹配滤波器,避免了脉压失配现象的产生,然后根据匹配滤波结果提出改进的广义Radon傅里叶变换算法,对运动参数的多维搜... 本文提出一种宽带双基地雷达高速多目标检测算法。针对目标高速运动产生的尺度因子和脉内多普勒,本文设计出一种新的匹配滤波器,避免了脉压失配现象的产生,然后根据匹配滤波结果提出改进的广义Radon傅里叶变换算法,对运动参数的多维搜索同时补偿脉内多普勒,从而获得相参积累峰值,不同峰值所对应的各阶参数即为不同目标的等效运动参数估计值,最后对补偿后的相参积累结果进行恒虚警检测处理,实现对高速目标的检测与参数估计。仿真结果表明,本文方法可有效消除脉内多普勒带来的匹配滤波损失,实现宽带雷达体制下高速目标的相参积累,从而验证了所提算法的有效性。 展开更多
关键词 宽带雷达 高速目标检测 脉内多普勒 广义Radon傅里叶变换
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逆合成孔径激光雷达回波信号特征分析 被引量:5
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作者 阮航 吴彦鸿 叶伟 《激光与红外》 CAS CSCD 北大核心 2013年第4期385-390,共6页
逆合成孔径激光雷达(inverse synthetic aperture ladar,ISAL)发射信号具有超短波长、超大带宽的特点,其回波对目标运动具有极强的敏感性,因而ISAL回波信号特征与常规ISAR回波有很大不同。建立了ISAL回波的精确模型,研究了由于目标运动... 逆合成孔径激光雷达(inverse synthetic aperture ladar,ISAL)发射信号具有超短波长、超大带宽的特点,其回波对目标运动具有极强的敏感性,因而ISAL回波信号特征与常规ISAR回波有很大不同。建立了ISAL回波的精确模型,研究了由于目标运动引起的回波包络展缩、脉内多普勒和脉冲间多普勒效应,并给出了它们的近似方法及约束条件,仿真分析了目标在不同运动参数下回波信号的包络展缩、脉内多普勒效应对ISAL成像的影响,结果表明上述效应会造成图像的散焦,需要在成像中进行相应补偿。 展开更多
关键词 逆合成孔径激光雷达 回波特征 包络展缩 脉内多普勒 仿真
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星载SAR地基侦察信号建模与仿真 被引量:1
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作者 叶伟 刘鑫 高阳 《舰船电子对抗》 2012年第5期61-65,共5页
对星载合成孔径雷达(SAR)的侦察可以为合成孔径雷达电子战提供有力的支援。在地基侦收站跟踪侦察星载SAR的背景下,建立了星载SAR地基侦察信号的数学模型。该模型利用真实卫星的天线参数及轨道参数,充分考虑了脉内多普勒频率因素。在侦... 对星载合成孔径雷达(SAR)的侦察可以为合成孔径雷达电子战提供有力的支援。在地基侦收站跟踪侦察星载SAR的背景下,建立了星载SAR地基侦察信号的数学模型。该模型利用真实卫星的天线参数及轨道参数,充分考虑了脉内多普勒频率因素。在侦察场景模型基础上,计算了条带模式下方位向的天线增益,通过仿真分析了星载SAR地基侦察信号,为星载SAR参数估计等研究奠定了基础。 展开更多
关键词 星载合成孔径雷达 天线增益 数学模型 脉内多普勒频率
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INTRACRANIAL ARTERIAL OCCLUSIVE LESION IN PATIENTS WITH GRAVES DISEASE 被引量:14
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作者 Jun Ni Shan Gao Li-ying Cui Shun-wei Li 《Chinese Medical Sciences Journal》 CAS CSCD 2006年第3期140-144,共5页
Objective To investigate the distribution and clinical manifestations of intracranial arterial occlusive lesions (IA- OLs), and their correlation with thyroid function. Methods We enrolled 7 patients who had Graves... Objective To investigate the distribution and clinical manifestations of intracranial arterial occlusive lesions (IA- OLs), and their correlation with thyroid function. Methods We enrolled 7 patients who had Graves' disease (GD) with IAOLs screened and evidenced by transcranial Doppler, then further confirmed with digital substract angiography in 2 patients and magnetic resonance angiography in 5 patients. Brain magnetic resonance imaging (MRI) was performed in all 7 patients. Three patients were followed up. Results Among 7 patients, 1 was male and 6 were females. The mean age was 32.0 ± 5.5 ( range from 11 to 49) years old. Six of them had symptoms of GD but one was asymptomatic with abnormality of I3, T4, and thyroid stimulating hormone. The lesions of intracranial arteries were symmetrical bilaterally in the intemal carotid artery system in 6 patients, as well as asymmetrical in 1 patient. Terminal internal carotid artery (TICA) were involved in all 7 patients. Middle cerebral artery (MCA) were involved in 3, anterior cerebral artery in 2, and basilar artery in 1 patient. Net-like collateral vessels and mimic moyamoya disease were observed in the vicinity of the occlusive arteries in 2 patients. All patients presented symptoms of ischemic stroke including transient ischemic attack and/or infarction while IA- OLs were found. Three patients had obvious involuntary movements. Brain MRI revealed infarctions located in the cortex, basal ganglion, or hemiovular center in 5 patients. The remaining 2 patients had normal brain MRI. The neurological symptoms were improved concomitant with relief of the thyroid function in 2 patients, while IAOLs were aggravated with deterioration of the thyroid function in 1 patient. Conclusion IAOLs in patients with GD mainly involve intracranial arteries, especially the TICA and MCA, which is similar to moyamoya disease. The neurological symptoms and severity of involved arteries may relieve while the hyperthyroidism is gradually under control. 展开更多
关键词 Graves'disease transcranial Doppler intracranial arterial stenosis occlusive disease
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Coronary bypass revascularization with radial artery and internal mammary artery grafts
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作者 甄文俊 佟宏峰 +5 位作者 王永忠 孙耀光 黄文 马玉健 田家政 吴良洪 《Chinese Medical Journal》 SCIE CAS CSCD 2002年第1期55-57,146,共3页
Objective To evaluate radial artery (RA) and internal mammary artery (IMA) grafts in coronary artery bypass and the use of color Doppler ultrasound in the peri-operative evaluation of IMA and radial-ulnar collateral ... Objective To evaluate radial artery (RA) and internal mammary artery (IMA) grafts in coronary artery bypass and the use of color Doppler ultrasound in the peri-operative evaluation of IMA and radial-ulnar collateral circulation.Methods From June 1998 to June 2000, sixty cases of coronary bypass revascularization with RA and IMA were performed. Preoperatively, the radial-ulnar collateral circulation was evaluated with the modified Allen’s test, color Doppler ultrasound and noninvasive oxygen saturation measurement. The IMA lumen and blood flow were measured at the first intercostal space with color Doppler ultrasound preoperatively and postoperatively.Results One patient (1.7%) died of serious cardiac arrhythmia on the fourth postoperative day. There were no arterial graft harvest related complications. Before harvesting, the ulnar artery blood flow was 30.78±9.71?ml/min, and it increased to 43.36±13.98?ml/min (40.87% increase, P【0.01) after the operation. Compared with the baseline, there was no obvious change of IMA blood flow postoperatively (P】0.05), but the systolic/diastolic flow ratio markedly decreased from 8.57±3.98?ml/min to 3.41±4.87?ml/min (P【0.01).Conclusions Arterial grafts can be safely used for coronary bypass revascularization with good results. The ulnar artery blood flow can increase compensatively after RA harvesting. The diastolic blood flow of grafted IMA markedly increased postoperatively. Color Doppler ultrasound was very helpful both in evaluating the radial-ulnar collateral circulation before RA harvesting and in assessing the patency of the grafted IMA after coronary artery bypass grafting (CABG). 展开更多
关键词 coronary artery bypass · radial artery · internal mammary artery · Doppler ultrasound
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