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一种基于随机共振增强的协方差矩阵频谱感知算法 被引量:2
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作者 张少文 王军 +1 位作者 陈伟 李少谦 《信号处理》 CSCD 北大核心 2011年第11期1633-1639,共7页
为了在避免对主用户系统产生有害干扰的同时提高频谱利用效率,要求认知无线电系统的频谱感知算法能在极低的信噪比下快速检测出主用户信号。由于可以避免能量检测面临的噪声不确定性问题,基于协方差矩阵的检测算法是一种有效的盲频谱感... 为了在避免对主用户系统产生有害干扰的同时提高频谱利用效率,要求认知无线电系统的频谱感知算法能在极低的信噪比下快速检测出主用户信号。由于可以避免能量检测面临的噪声不确定性问题,基于协方差矩阵的检测算法是一种有效的盲频谱感知算法。为了进一步提高极低信噪比下的性能,本文提出了一种基于随机共振的协方差矩阵频谱感知算法。该算法通过在接收信号中加入优化的特定信号,利用随机共振原理,增大有无主用户信号下的检测统计量概率分布函数的分离度,提高频谱感知的性能。仿真结果表明,相对于现有的协方差矩阵频谱感知算法,在相同的虚警概率下,所提算法可以显著提高极低信噪比下的检测概率,同时大幅度缩减检测时间。 展开更多
关键词 随机共振 协方差矩阵检测 频谱感知 认知无线电
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Experimental measurement of covariance matrix of two-mode entangled state 被引量:2
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作者 YU XuDong LI Wei +1 位作者 JIN YuanBin ZHANG Jing 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第5期875-879,共5页
A two-mode entangled state was generated experimentally through mixing two squeezed lights from two optical parametric amplifiers on a 50/50 beam splitter.The entangled beams were measured by means of two pairs of bal... A two-mode entangled state was generated experimentally through mixing two squeezed lights from two optical parametric amplifiers on a 50/50 beam splitter.The entangled beams were measured by means of two pairs of balanced homodyne detection systems respectively.The relative phases between the local beams and the detected beams can be locked by using the optical phase modulation technique.The covariance matrix of the two-mode entangled state was obtained when the relative phase of the local beam and the detected beam in one homodyne detection system is locked and the other is scanned.This method provides a way by which one can extract the covariance matrix of any selected quadrature components of two-mode Gaussian state. 展开更多
关键词 optical parametric amplifier Gaussian entangled state covariance matrix
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