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相位对比磁共振成像中的扰相射频脉冲分析
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作者 邹云鹏 付长信 康雁 《东北大学学报(自然科学版)》 EI CAS CSCD 北大核心 2015年第5期631-635,共5页
应用仿真实验研究了在基于梯度回波的2维相位对比磁共振序列中扰相射频脉冲的作用,应用模体和志愿者实验来确定在准确测量血流的前提下扰相射频脉冲对相位对比磁共振图像和血流测量结果的影响.相位对比磁共振对血流的测量结果显示:当扰... 应用仿真实验研究了在基于梯度回波的2维相位对比磁共振序列中扰相射频脉冲的作用,应用模体和志愿者实验来确定在准确测量血流的前提下扰相射频脉冲对相位对比磁共振图像和血流测量结果的影响.相位对比磁共振对血流的测量结果显示:当扰相梯度充足时,是否使用扰相射频脉冲对测量结果无明显影响;但是当扰相梯度不充分时,使用扰相射频脉冲成像测量的血流更准确;并且使用扰相射频脉冲可以改善图像的对比度,更容易区分血流区域和静态组织. 展开更多
关键词 磁共振成像 相位对比 扰相射频脉冲 对比度噪声比 梯度回波
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Anti-interference method for HF radars by transmitting phase-modulated chirps
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作者 周浩 Wen Biyang +1 位作者 Ma Zhigang Wu Shicai 《High Technology Letters》 EI CAS 2006年第4期392-396,共5页
Radio frequency interference (RFI) is a major problem in high-frequency (HF) radars. Conventional filtering-involved RFI suppression methods may introduce distortions to the target signals of interest and often de... Radio frequency interference (RFI) is a major problem in high-frequency (HF) radars. Conventional filtering-involved RFI suppression methods may introduce distortions to the target signals of interest and often demand extra hardware costs. In this paper, a novel method for RFI suppression by using linearly or randomly phase-modulated (PM) chirps is proposed, which enables independent analyses of the target signal and the RFI. Furthermore, the directions of arrival (DOA) of the interference are used as constraints to ensure a better DOA estimation of the target. The effectiveness of the method is demonstrated by numerical simulation results. The method can greatly improve the anti-interference capabilities of HF radars and is extremely applicable in the portable and low-cost radar systems. 展开更多
关键词 HF radar radio frequency interference phase modulation direction of amval MUSIC
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