One Method of Standard Recognition of Underwater Acoustic Signal

研究了制式识别的特征参数提取方法,以小波变换为主,结合瞬时频率统计算法、高阶谱等多种识别算法,对现有水下通信信号调制方式进行类间、类内识别,包括多载波（OFDM）和单载波（MFSK、MPSK和QAM）。仿真结果表明,文章所采用的方法在低信噪比下的识别概率均能保持在82%以上,具有较好的识别性能。This article did a research on themethod of characteristic parameter obtainment. Based on Wavelet Transform, instantaneous parameter extraction and higher-order cumulants are used to recognize the Underwater Sound Signal, including Single carrier（MFSK,MPSK, QAM） and multicarrier（OFDM）. Simulation results show that the rate of modulation identification is able to keep 82% above in the situation of low SNR, meaning that the proposed method has a good ability of identification.国家自然科学基金（61471309,61671394）; 中央高校基本科研业务费专项资金（20720170044

Research and simulation on underwater acoustic communication channel

文中提出的时变多径水声信道模型基本上实现了对海洋水声信道的模拟,在一定程度上反映了海洋介质的物理特性;对Rayleigh衰落模型的仿真,反映了海洋介质的不均匀性以及信号在水声信道中传输的时变特性。每种信道模型都是对真实信道的近似模拟,必然有其适用的范围,要建立更加完善的信道模型还需要对更复杂的环境参数和信号的多径时变特性做进一步研究。A computer simulation method of the multipath and time-variance underwater acoustic channel based on ray theory and statistical properties of the signal is proposed.Computer simulations of the channel with Rayleigh fading are performed,and the results are helpful to understand the characteristics of the underwater acoustic communication channel and to design underwater acoustic communication systems.水声通信中的OFDM技术关键问题研究及DSP实现(60572106

航空弹药动态调运决策优化建模与仿真研究

针对航空弹药调运决策问题,综合考虑战场实时交通状况和敌方攻击等不确定性因素以及各航空弹药保障部门之间的协同作用,将道路交通状况和敌方攻击情况转化为路段通行时间参数,基于多源时间最短路径问题以及Floyd-Warshall算法对模型进行求解,得到了航空弹药最优运输路径以及参与调配的储存点组合。通过作战环境中航空弹药调运问题的仿真研究,将航空弹药动态调运决策模型与传统的模型进行了对比分析,发现动态调运决策模型可以根据作战情况及时调整调运决策,能够为作战提供更加可靠的保障。国家自然科学基金(71371051,61471309,61671394)资

Estimating parameters of hyperbolic modulation frequency signal based on cascade dictionary

为降低水下通信中出现的多径和多普勒效应,提高水下目标探测精度,采用双曲调频信号作为探测信号,利用双曲调频信号(hyperbolic modulation frequency,HFM)时频变化具有双曲线的特征,通过建立HFM信号时间-尺度级联原子库模型,在原子库中寻找最优解,进而对HFM信号的两个频率变化因子进行估计。计算机仿真和水池实验的结果均证明,相较于现在常用的小波-拉东变换(wavelet-Radon)估计方法,本方法的均方根误差小于1%,因此在水下目标探测中有较大的应用价值。To reduce the multi-path and Doppler effects occurring in underwater communications and to increase the precision of underwater target detection,we employ a modulation frequency signal as the detection signal. A hyperbolic modulation frequency( HFM) signal is hyperbolic in the time-frequency domain. In view of this feature,we establish a time-scale cascade dictionary model to find the optimal solution; furthermore,two frequency variation factors of the HFM signal are estimated. The simulation results and the pool trials show that the proposed algorithm performs well,and its accuracy is superior to that of the commonly used wavelet-Radon transform. The root mean square error of the frequency variation factors is 1% lower than that achieved using the wavelet Radon transform.This demonstrates the potential of the suggested algorithm for underwater target detection.国家自然科学基金项目(61471309,61107023);; 国家教育部博士点基金项目(20110121120020);; 福建省自然科学基金项目(2013J01258);福建省自然科学基金项目(2010J01344);; 福建省重点基金项目(2012H1012

Implementation of carrier interferometry OFDM by using pulse shaping technique in frequency domain

This paper presents a novel design of carrier interferometry (Cl) spreading codes by Using inverse fast Fourier transform (IFFT) instead of linear transform matrix. Pulse shaping method in frequency domain is used to generate different carrier interferometry orthogonal frequency division multiplexing (CI/OFDM) signals. Peak-to-average power ratio (PAPR) performance has been compared among OFDM, original CI/OFDM and our proposal. Simulation results show that our proposal could simplify the system implementation and improve the signal processing efficiency without PAPR performance degradation

基于Multi-Agent的应急物资储存点布局优化研究

针对应急物资储存点布局优化问题,综合考虑到应急物资保障Agent和应急物资需求Agent的独立性以及指挥Agent的协同作用,基于Multi-Agent方法建立考虑多种因素共同影响的应急物资储存点布局优化模型,并结合优序数法和改进的遗传算法对不同量纲的多目标优化问题进行求解,从而确定应急物资储存点布局最优组合以及每个储存点的物资储备量。仿真结果表明,基于Multi-Agent的应急物资储存点布局优化模型可以协同各部门的意见,从成本、安全和时间多个角度为应急物资保障提供更加合理的布局决策。国家自然科学基金项目“基于复杂网络与Multi-Agent融合的金融市场间风险溢出效应研究”(项目编号:71371051

Application of weighted fractional Fourier transform in hybrid system

为提高通信系统在复杂水声环境下的鲁棒性,提出基于加权分数傅里叶变换WFRFT(weighted fractional Fourier transform)的混合载波系统.对混合系统进行优化设计,以最低误比特率为优化目标,求解得到系统的最优变换阶次,得到优化的系统性能.仿真和水池实验表明,基于WFRFT的混合载波系统在多径信道下的误比特率介于传统的单/多载波系统之间;而在双选信道下,其最优阶的系统性能优于单/多载波系统.该混合系统具有单/多载波的优良性能,在提高通信系统鲁棒性方面,具有很大的应用前景.To improve the robustness of the communication system in complex underwater acoustic environment,the hybrid carrier system based on WFRFT was put forward. To obtain the optimal transformation order,the hybrid carrier system is designed with the lowest bit error rate as optimization goal. Simulation results show that BER performance of hybrid carrier system is between the traditional single / multi carrier systems in multipath channels.However,system performances with the optimal order are superior to single / multi carrier systems under the doubly selective fading channels. It has the excellent characteristics of the single / multi carrier systems and it is thus prospective in improving the robustness of the communication system.国家自然科学基金(61471309);; 福建省自然科学基金(2013J01258

理想声源辐射声场的数值分析

通过声场的特性和规律分析可以识别和定位噪声源,对噪声控制以及声源的设计提供参考。数值方法是求解有源声场的重要工具,复杂的声辐射一般可分解为简单的声辐射叠加。研究了单极子、偶极子、活塞等几种理想声源辐射声场的解析解,并用有限元法计算数值解,得到相应的辐射声场,包括声压、速度、指向性等量,有限元法得到的数值结果与解析解吻合;利用有限元法计算了点声源的线性阵列与平面阵列等典型的叠加声场。对各种声源的特性和辐射声场的规律以及在工程领域中的应用进行了归纳。国家自然科学基金项目(51505261);;山东省自然科学基金项目(ZR2015AM013

Influence of Chaotic IIR Filter on Nonlinear Dynamic Characteristic of Underwater Acoustic Signal

本文探讨了混沌滤波器在水声信号处理中的一种新的应用.混沌蔡氏电路产生的信号进行频带调制和高通IIr滤波后,由水声换能器发射并经过水池传播和接收.实验结果表明混沌滤波器实现了频带搬移,且接收到的水声信号具有与原始的混沌发射信号相似的宽频带特性.进一步,运用非线性动力学方法对原始混沌电路信号和接收水声信号进行时间序列分析比较.发现接收的水声信号具有比发射的原始混沌信号更为不规则的重建相空间和更高的分形维数.混沌滤波器运用于水声信道提高了接收信号的非线性复杂特性.A new application of chaotic filter in underwater acoustic signal processing is described.After frequency modulation and high-pass IIR filtering,the chaotic signal generated by the Chua's circuit was transmitted through a underwater sound channel.The received acoustic signal shows similar frequency band characteristic with chaotic circuit.Furthermore,nonlinear dynamic analysis is applied to compare the underwater acoustic signal and the original circuit signals.The results show that the acoustic signal has more irregular phase space and higher fractal dimension than chaotic circuit signals.Chaotic filter increases the complexity of the underwater signal

OFDM Transform-domain Channel Estimation Based on MMSE for Underwater Acoustic Channels

In this paper, we present a method of transform-domain channel estimation for orthogonal frequency division multiplexing (OFDM). The estimator based on minimum mean squared error (MMSE), and a process of FFT and IFFT is added. The system has been tested in a real underwater acoustic channel - the experimental pool in Xiamen University. The experimental result shows that the transform-domain channel estimation has improved the performance of the OFDM system in underwater acoustic channels