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针对混响环境中,多径效应、散射、衍射等原因导致声源定位失败或分辨能力不足的现象,提出一种基于主导声源检测MUSIC群时延的邻近多声源定位方法。该方法采用球形传声器阵列,相比平面阵列可以捕获3D声场信息,利用球谐域下信号的频率分量与角度分量解耦的优势,从而可直接利用频率平滑技术处理宽带语声信号而不需要构造聚焦矩阵,并在球谐域下通过设置阈值对一组时频段进行主导声源检测,从而选择出包含直达声的一组时频块来构造MUSIC群时延空间谱。上述举措在提升波达方向估计在高混响环境下定位鲁棒性的同时,也提高了多个邻近声源的分辨能力。仿真实验结果表明,所提出的主导声源检测MUSIC群时延算法,在高混响和低信噪比条件下,仍具有更好的定位精度与更优的邻近多声源分辨效果。 相似文献
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An optical time-domain differentiation scheme is proposed and demonstrated based on the intensive differential group delay in a high birefringence fibre waveguide. Results show that the differentiation waveforms agree well with the mathematically calculated derivatives. Both error and efficiency will increase when the birefringence fibre becomes longer, and the error rises up more quickly while the efficiency approaches to a maximum of ~0.25. By using a 1-m birefringence fibre a lower error of ~0.26% is obtained with an efficiency of 1% for the first-order differentiation of 10-ps Gaussian optical pulses, and the high-order optical differentiation up to 4th order is achieved with an error less than 3%. Due to its compact structure being easy to integrate and cascade into photonic circuits, our scheme has great potential for ultrafast signal processing. 相似文献
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利用遗传算法优化线性啁啾光栅性能 总被引:3,自引:2,他引:1
针对制作町用于40 Gb/s全光色散补偿的宽带线性啁啾光栅时出现带内群时延纹波波动较大等问题.提出了一种通过设计和改变切趾函数的参量来优化线性啁啾光栅的新方法.该方法实现简单.只需根据需要设计具有不同滚降特性的切趾函数,同时利用遗传箅法来优化切趾参量.结合传输矩阵法经过200代获得了低带内时延纹波的线性啁啾光栅.数值结果验证了采取非对称分段切趾法在保持反射谱宽和平坦性的同时可以抑制带内群时延纹波的优越性.利用该方法制作了反射谱工作带宽为1.06 nm、时延纹波不超过45.60 ps、可用于大容量密集波分复用系统(DWDM)色散补偿的线性啁啾光纤光栅. 相似文献
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提出一种3模12芯光纤的纤芯排布优化方法.在分析芯间串扰、弯曲半径阈值和相对纤芯多重性因子等特性后,给出了单圆形结构和方点阵结构的纤芯排布方法及优化方案.对于单圆形结构,在波长为1 625nm的情况下很难找到合适纤芯排布以使芯间串扰小于-30dB/100km并且使光缆截至波长小于1 530nm.对于方点阵结构,在波长为1 625nm,且弯曲半径大于弯曲半径阈值时,可使芯间串扰小于-30dB/100km,最大光缆截至波长不大于1 530nm,纤芯多重性因子可达到~15,这表明方点阵结构是一种比单圆形结构更适合3模12芯光纤的纤芯排布结构. 相似文献
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Experimental Generation of Narrow-Band Paired Photons: from Damped Rabi Oscillation to Group Delay 下载免费PDF全文
We report the experimental generation of narrow-band paired photons through electromagnetically induced transparency and spontaneous four-wave mixing in a two-dimensional magneto-optical trap (2D MOT). By controlling the optical depth of the 2D MOT from 0 to 40, the temporal length of the generated narrow-band paired photons can be varied from 50 to 900 ns. The 'transition' between damped Rabi oscillation and group delay is observed undisputedly. In the damped Rabi oscillation regime, a violation factor of the Cauchy–Schwartz inequality as large as 6642 is observed. In the group delay regime, sub-MHz linewidth (~0.65 MHz) paired photons are obtained with a generation rate of about 0.8×105 s?1. 相似文献