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采用相位调制方法的光纤干涉仪 被引量:6
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作者 倪畅 张鸣 朱煜 《光学精密工程》 EI CAS CSCD 北大核心 2017年第4期820-826,共7页
为了实现小巧紧凑且使用灵活的大量程位移测量,提出了一种采用相位调制方法的光纤干涉仪。首先,介绍相位调制方法,分析内调制与外调制的特点,指出由于内调制的局限性,外调制更适于较大量程的位移测量。然后,用数学推导和MATLAB仿真对已... 为了实现小巧紧凑且使用灵活的大量程位移测量,提出了一种采用相位调制方法的光纤干涉仪。首先,介绍相位调制方法,分析内调制与外调制的特点,指出由于内调制的局限性,外调制更适于较大量程的位移测量。然后,用数学推导和MATLAB仿真对已有的位移解算算法中的反正切法与微分交叉相乘法进行分析,证明在毫米级量程的位移测量中反正切法优于微分交叉相乘法。最后,搭建了采用相位调制方法的光纤干涉仪,并进行了实验验证。实验结果表明:相比于微分交叉相乘法,反正切法更适用于毫米级以上量程的位移测量,基于相位调制的光纤干涉仪在毫米级步进运动中的相对误差最大为255.21nm,标准差为78.56nm,基本满足高精度大量程的位移测量需求。 展开更多
关键词 光纤干涉仪 相位调制方法 相位调制 位移解算 反正切法
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NPC三电平逆变器共模电压及中点电位波动协同抑制方法 被引量:6
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作者 王萍 戚银 张云 《电力系统及其自动化学报》 CSCD 北大核心 2018年第10期28-33,共6页
为协同抑制NPC三电平逆变器的共模电压以及中点电位波动,本文提出了一种新型反相位排列POD调制方法,在分析小矢量与大矢量对共模电压以及中点电位波动影响的基础上,将空间矢量图中每个大扇区划分为6个小扇区,并在不同小扇区中选择注入... 为协同抑制NPC三电平逆变器的共模电压以及中点电位波动,本文提出了一种新型反相位排列POD调制方法,在分析小矢量与大矢量对共模电压以及中点电位波动影响的基础上,将空间矢量图中每个大扇区划分为6个小扇区,并在不同小扇区中选择注入不同零序分量。与传统POD调制方法相比,本文所提方法能够协同抑制共模电压以及中点电位波动。仿真和实验验证了本文所提方法的有效性与可行性。 展开更多
关键词 三电平逆变器 相位排列调制方法 共模电压 中点电位波动 协同抑制
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SERIALLY CONCATENATED CONTINUOUS PHASE MODULATION WITH REDUCED ITERATIVE DEMODULATION AND DETECTION 被引量:3
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作者 Sun Jinhua Li Jiandong Jin Lijun 《Journal of Electronics(China)》 2007年第1期16-22,共7页
A reduced state Soft Input Soft Output (SISO) a posteriori probability algorithm for Seri-ally Concatenated Continuous Phase Modulation (SCCPM) is proposed in this paper. Based on the Reduced State Sequence Detection ... A reduced state Soft Input Soft Output (SISO) a posteriori probability algorithm for Seri-ally Concatenated Continuous Phase Modulation (SCCPM) is proposed in this paper. Based on the Reduced State Sequence Detection (RSSD),it has more general form compared with other reduced state SISO algorithms. The proposed algorithm can greatly reduce the state number,thus leads to the computation complexity reduction. It also minimizes the degradation in Euclidean distance with decision feedback in the reduced state trellis. Analysis and simulation results show that the perform-ance degradation is little with proper reduction scheme. 展开更多
关键词 Concatenated codes Continuous Phase Modulation (CPM) Soft Input Soft Output (SISO) Euclidean distance
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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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