Physics‐based spectral sharpening through filter‐chart calibration

The spectral overlap of color‐sampling filters increases errors when using a diagonal matrix transform, for color correction and reduces color distinction. Spectral sharpening is a transformation of colors that was introduced to reduce color‐constancy errors when the colors are collected through spectrally overlapping filters. The earlier color‐constancy methods improved color precision when the illuminant color is changed, but they overlooked the color distinction. In this article, we introduce a new spectral sharpening technique that has a good compromise of color precision and distinction, based on real physical constraints. The spectral overlap is measured through observing a gray reference chart with a set of real and spectrally disjoint filters selected by the user. The new sharpening method enables to sharpen colors obtained by a sensor without knowing the camera response functions. Experiments with real images showed that the colors sharpened by the new method have good levels of color precision and distinction as well. The color‐constancy performance is compared with the data‐based sharpening method in terms of both precision and distinction. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 564–576, 2015     

A Combined Antenna Array and Multi-User Detection DS-CDMA Receiver in Single-Path and Multi-Path Fading Channels

An adaptive antenna array is incorporated into a decorrelatingmulti-user detector to effectively increase the DS-CDMA system capacity.Capacity improvement is due to beamforming gain, spatial diversity gain(assuming large angle spread), and the decorrelating effect. Thereceiver has been analyzed for the cases of sufficiently andinsufficiently spaced receiving antennas. The receiver consists of afront-end beamformer for every user in the cell and has knowledge of allusers' signature sequences. The beamformer estimates the desired userchannel vector, enhancing its signal and reducing the co-channelinterference from other directions. The multi-user detection, exploitingknowledge of other users, rejects those interferers whose arrival anglesare close to that of the desired user. The average uncoded Bit ErrorRate (BER) as a function of the number of in-beam active users, theaverage antenna Signal-to-Noise Ratio (SNR), and the number of receivingantennas is examined in both single-path and multi-path Rayleigh fadingchannels. Analysis shows an increase in system capacity proportional tothe number of receiving antennas.     

多用户检测中解相关检测和最小均方误差检测的研究

多用户检测技术是第三代移动通信系统关键技术之一。其主要思想是充分利用所有用户的信息对接收信号做联合检测,抑制多址干扰,缓解＂远-近＂效应,从而有效地提高系统容量。本文对多用户检测技术进行初步的研究,尤其是两种主要的线性多用户检测技术：解相关检测和最小均方误差检测,做仔细地研究和比较,并用MATLAB在AWGN信道下和DS-CDMA系统中做仿真。     

A binary pattern classification using potts model

The paper offers a new kind of neural network for classifying binary patterns. Given the dimensionality of patterns, the memory capacity of the network grows exponentially with free parameter s. The paper considers the limitations for parameter s caused by the fact that greater values of demand large computer memory and decrease the basin of attraction we have. In contrast to similar models, the network enjoys larger memory capacity and better recognition capabilities—it can distinguish heavily distorted patterns and even cope with pattern correlation. The negative effect of the latter can be easily suppressed by taking a large enough value of s. A perceptron recognition system is considered to demonstrate the efficiency of the algorithm, yet the method is quite applicable in fully connected associative-memory networks. The article is published in the original.     

探地雷达回波信号的特征提取和分类

探地雷达的回波信号具有非平稳特征.为实现非平稳信号的检测和分类,采用了二进小波变换、主分量分析与Fisher线性判别分析和前馈多层感知器分类器分别对探地雷达回波信号进行小波分解、去相关与特征选择和分类.实验结果表明,该算法具有很好的分类效果.     

基于多个时间点联合解相关的卷积盲源分离

实际信号的混合均为卷积混合,且信号是非平稳的。盲源分离的目标就是找到一组分离滤波器,使得源信号的估计信号互相统计独立。结合信号的非平稳性,利用二阶解相关原理,文章阐明了一种在频域实现卷积混合的盲源分离算法,并且考虑了噪声对分离性能的影响。为了避免频点排列次序的不确定性,利用了多阶段盲源分离思想。利用该算法,对两路混合的实录水声信号进行盲分离,得到了两路源信号的估计信号,通过对估计信号的分析,利用信噪比提高率这一标准,验证了该算法的有效性。该算法收敛速度快,精度高,可用于浅海环境下实录水声混合信号的盲分离。     

基于非线性空时编码系统的自适应信道估计

用非线性分组编码，在时间选择性衰落信道环境下，将基本LMS自适应算法推广到对二维空时编码信号的权矩阵自适应迭代估计，分析了对输入信号序列编码所生成的非线性编码矩阵之间的相关性，运用解相关LMS自适应算法对衰落信道进行估计．在不同噪声情况下，根据估计信道和噪声统计量，推导了对非线性编码进行解码的最大似然决策方法．仿真试验表明，采用扩展LMS算法和解相关LMS算法跟踪时变衰落信道响应具有较强的鲁棒性和快速收敛性，非线性空时分组编码系统相对干线性编码系统提高了编码系统性能，运用最大似然决策方法进行解码降低了系统误码率．     

多用户检测技术的发展与应用

CDMA系统是一个自干扰系统，多址干扰是限制其容量和性能的主要原因之一，传统的相干接收机不能从根本上解决消除多址干扰的问题，因此如何抑制多址干扰引起了通信界学者们的关注．多用户检测技术能从根本上消除多址干扰，提高系统的性能。文中主要介绍了多用户检测的思想和检测器的分类，以及衡量多用户检测器性能的三个重要指标，还阐述了多用户检测技术的新发展和该技术在几个具体系统中的应用。     

近似解相关多用户检测算法的FPGA实现

简要介绍了近似解相关 (AD)多用户检测算法 ,通过对算法的分析 ,建立了该算法的实现框架 ,给出了用 FPGA技术实现该算法模块的详细方案 ,并从实际硬件量的角度分析了其复杂度。最后以DSP2 6 2 1EA评估板为基本硬件平台对该方案进行测试 ,测试结果和理论分析基本吻合 ,说明了该方案是可行的。     

Monitoring mine collapse by D-InSAR

For harmful ground collapse and its special deformation characteristics,which causes SAR images to lose coherence,InSAR technology cannot be applied in monitoring surface collapse in mining areas.We took the Shenmu mining area in northern Shaanxi province as an example to study subsidence in mining areas and proposed an interpolated multi-view processing method.The results show that this method can improve the detectable deformation gradient to a certain extent and can become a good reference value for monitoring large scale gradient deformation.We also analyzed the rules for temporal decorrelation in mining.