数字调制信号识别系统的DSP硬件实现

针对人工的信号识别设备不足,设计了基于DSP的数字调制信号识别系统．使用希尔伯特变换提取信号的瞬时信息,计算得到3个特征参数值,使用决策树分类器对信号进行分类．设计了用于通信信号识别的硬件系统,并制作了实际电路．在CCS软件环境下,使用c语言编程实现了调制信号自动识别算法．DSP硬件仿真结果表明,在信噪比不小于10dB时,系统平均识别正确率超过了98％．最后使用系统对信号发生器产生的调制信号进行了实时离线识别,实验结果表明,系统具有较好的识别正确率和实时性．     

规范化自相关函数的复杂PRI调制样式识别

针对当前复杂PRI调制样式难以有效识别的问题,提出了一种基于规范化自相关函数的复杂PRI调制样式识别算法。该算法首先求出4种PRI脉冲序列的自相关函数,在对自相关函数做规范化的基础上,定义了峰值密度,陡峭度,序列能量3个特征量并建立特征空间,通过比较特征量与门限值进行判决,识别出PRI调制样式。仿真结果表明:本文算法在单组脉冲数目为100个、信噪比为4dB时,识别正确率可以达到95%;在单组脉冲数目为80个时,识别正确率可以达到95.5%;在单组脉冲数目为100个、脉冲丢失率达到25%时,识别正确率仍保持在93%以上。     

基于信噪比估计和盒维数的调制信号识别

针对数字调相和调频识别问题,提出采用调制信号绝对值的瞬时幅度的盒维数作为多进制数字相位调制(MPSK)和多进制数字频率调制(MFSK)信号类间识别的特征参数,并采用拟合曲线作为判决门限,该方法在保持具有较少的特征参数的同时还增强了对噪声的鲁棒性.在调制信号的类内识别中,分别采用MPSK信号的瞬时相位的盒维数和MFSK信号的瞬时频率的盒维数作为特征参数.仿真结果表明,在信噪比为5 dB时,对信号进行完全识别的正确率可以达到90％以上,从而证明了该方法的有效可行性.     

基于支持向量机的多类数字调制方式自动识别算法

为了解决软件无线电系统中多种调制方式之间切换的问题，提出了一种基于支持向量机的多类数字调制方式识别算法．该算法通过提取有效的特征向量以区分不同的调制方式，并基于支持向量机和判决树分类思想，将特征向量映射到高维空间中加以分类。解决了样本在低维空间中的非线性不可分问题，避免了判决门限的确定，与传统的神经网络方法相比，具有更好的泛化推广能力．仿真结果表明，在具有加性带限高斯噪声的环境下，信噪比大于等于10dB时，识别正确率大于90％．     

某型装备数字通信信号识别能力的改进

针对某机载电子对抗任务系统数字通信信号识别正确率较低,影响该系统工作效能的问题,对Azzouz决策论的信号调制识别算法进行改进,改变了识别步骤,并采用可变的门限值,从而大大提高了该系统对数字通信信号的识别概率。经Matlab仿真得出,改进算法在信噪比大于8dB时,对信号的识别概率提高至95％,远高于原算法在信噪比大于10dB时,90％的识别概率。该算法仅用了5个门限参数,识别了包括噪声在内的7种信号,识别步骤最多3步,具有计算量小,实现简便的特点。     

基于谱分析的通信信号调制识别算法的研究

调制样式识别和调制参数估计是电子对抗中的一个重要环节,也是信号分析的一个快速发展的领域。本文在低信噪比的情况下完成了对信号调制样式的识别和调制参数的估计。由于谱相关函数具有对平稳噪声和干扰的不敏感性,所以在低信噪比下用谱相关理论具有一定的优势。本文提出识别算法可以识别2FSK,4FSK等信号。实验结果表明：本文提取的参数在对信号进行分类时,分类效果好。     

基于灰度共生矩阵的微动干扰分类识别

针对雷达成像中面临的调制转发微动干扰、微动散射波干扰、脉冲卷积微动干扰3种新型微动干扰样式的识别问题,提出一种基于灰度共生矩阵的干扰识别方法。该方法从图像域角度出发,首先对雷达接收信号矩阵进行灰度化处理,然后利用灰度共生矩阵提取其纹理参数并构造特征参数,最后采用KNN分类器实现了对雷达接收信号中目标回波和3种微动干扰样式的检测与识别。仿真实验结果表明,当信噪比为-5 dB时,不同干信比下4种信号样式的识别率均能够达到90%以上,每种信号样式整体识别率在98%以上;当信噪比为5 dB时,不同干信比下4种信号样式的识别率均能够达到95%以上,每种信号样式整体识别率在99%以上。     

数字通信信号调制方式识别算法的改进研究

为克服数字通信信号调制方式识别算法识别类型少,步骤复杂,识别率低等问题,在已有识别算法的基础上,通过对信号特征参数的分析和提取,提出一种基于决策理论的数字通信信号调制样式识别的改进算法。该算法通过比较不同信噪比下特征参数的取值概率直方图,选择判决门限值。同时,应用最大似然法则,并采用了可变的判决门限值,以得到最佳判决门限。研究结果表明,在信噪比（SNR：Signal to Noise Ratio）为10 dB时,算法的正确识别率达到96%以上,可识别包括噪声在内的7种信号,且信噪比为6～15 dB时,该算法的正确识别率不低于92%。     

基于密集连接机制的无线信号调制识别

为提高复杂信道环境下无线通信系统对调制信号的检测识别能力,以及针对当前调制识别方法存在的模型复杂、计算量大、输入数据特征不完备等问题。提出一种改进的深度学习算法模型,对真实无线环境下的9种常见调制信号进行识别研究。该算法通过对原始的同相正交(in-phase quadrature, IQ)数据进行幅度相位计算,以此增加模型输入数据的特征信息,采用改进的密集神经网络(dense neural network, DenseNet)对常见调制信号进行识别分类。实验结果表明：在相同的训练数据样本中,相比其他深度学习调制识别算法,改进算法性能最优。在信噪比为0时,DenseNet平均识别率达到84.6%。改进的IQ输入数据明显提高了无线信号的检测识别率,在信噪比为-10 dB和-5 dB时,调制信号的识别率提高了10%。     

遥测信号仿真系统中的数字调制识别应用

针对遥测信号特性仿真系统中的数字调制方式设计了一种基于判决树的数字调制自动识别方案。在加性高斯白噪声（AWGN）信道中,对遥测信号中常见的调制方式进行识别。通过MATLAB计算机仿真,验证了该方案的可行性。实验表明,在信噪比SNR为10dB条件下自动识别正确率不低于93％。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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