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空间自适应EPLL低频地震随机噪声降噪方法 被引量:1
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作者 林红波 马阳 《西安电子科技大学学报》 EI CAS CSCD 北大核心 2021年第6期204-211,共8页
期望块对数似然降噪方法从外部数据学习高斯混合模型作为地震信号先验,利用与图像块最匹配的高斯分量对数据块去噪,并与含噪图像加权实现图像重构,能够有效抑制地震图像中的随机噪声,保持图像细节。期望块对数似然算法采用与噪声方差有... 期望块对数似然降噪方法从外部数据学习高斯混合模型作为地震信号先验,利用与图像块最匹配的高斯分量对数据块去噪,并与含噪图像加权实现图像重构,能够有效抑制地震图像中的随机噪声,保持图像细节。期望块对数似然算法采用与噪声方差有关的正则化参数,在处理沙漠地震图像的非平稳信号和低频色噪声时很难兼顾弱信号保真与噪声压制。针对期望块对数似然正则化参数不适应非平稳地震信号问题,提出空间自适应期望块对数似然低频随机噪声降噪方法。该方法采用方差归一化对图像平稳化,根据图像块信噪比控制正则化参数,使其随非平稳地震勘探信号强度的时空变化而自适应调整,从而平衡局部细节的保持和非平稳信号全局特征的恢复。此外,在信号重构过程中,通过块信噪比对图像块加权平均,减少信号丢失。笔者采用空间自适应期望块对数似然算法对合成以及实际地震勘探图像去噪。结果表明,该方法可以有效地恢复沙漠地震勘探图像中非平稳信号,抑制低频弱相似随机噪声。 展开更多
关键词 沙漠地震图像 随机噪声压制 非平稳信号 块信噪比 期望块对数似然降噪方法
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Multi-Channel Iterative FDE for Single Carrier Block Transmission over Underwater Acoustic Channels 被引量:3
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作者 HE Chengbing HUO Siyu +2 位作者 ZHANG Qunfei WANG Han HUANG Jianguo 《China Communications》 SCIE CSCD 2015年第8期55-61,共7页
Recently, single carrier block transmission(SCBT) has received much attention in high-rate phase-coherent underwater acoustic communication.However,minimum-mean-square-error(MMSE) linear FDE may suffer performance los... Recently, single carrier block transmission(SCBT) has received much attention in high-rate phase-coherent underwater acoustic communication.However,minimum-mean-square-error(MMSE) linear FDE may suffer performance loss in the severely time dispersive underwater acoustic channel. To combat the channel distortion, a novel multi-channel receiver with maximum ratio combining and a low complex T/4 fractional iterative frequency domain equalization(FDE) is investigated to improve diversity gain and the bit error rate(BER) performance. The proposed method has been verified by the real data from a lake underwater acoustic communication test in November 2011. At 1.8 km, the useful data rates are around 1500 and 3000 bits/s for BPSK and QPSK respectively. The results show the improvements of system performance. Compared with MMSE FDE system, the output SNR improvement is 6.9 d B, and the BER is from 10-3 to no error bits for BPSK. The output SNR improvement is 5.3 d B, and the BER is from 1.91×10-2 to 2.2×10-4for QPSK. 展开更多
关键词 underwater acoustic communi-cation single carrier multi-channel frequency domain equalization iterative processing
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