共查询到20条相似文献,搜索用时 62 毫秒
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本文介绍近30年来水声信号处理领域理论研究的新进展和在声纳设计中的应用。包括水声信号建模、声场匹配、海洋波导和内波现象的探索和研究、声矢量场信息获取和处理,低频水声信道的时/空相关特性,水下目标辐射噪声的不变特征量提取和检测技术,水下语音、图像传输和抗干扰技术。同时概述,声纳设计的前沿领域:大孔径拖曳线列阵声纳、高分辨力合成孔径声纳、深海传呼机等的发展情况。 相似文献
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“超同步周期”水声定位技术研究与实现 总被引:2,自引:0,他引:2
水声同步定位系统在对水声目标进行定位的过程中,定位系统对于目标轨迹的采样率将随目标距离的增加而降低。从而使原始数据减少,并使定位系统的处理能力不能得到有效的利用。长期以来,这个矛盾一直没有得到解决。我们在对这一问题进行深入研究的基础上,发展了一种被称之为“超同步周期”水声定位的新技术,可以大大提高对于远距离水声目标轨迹的采样率。在电路实现过程中,又相应地开发出一种检测定位信号时延值的“余数算法”,并已成功地应用于实际系统。该系统在工作周期为0.4s、目标最大距离为6km的情况下,可以有效克服目标“距离模糊”现象,同时对五个目标进行正确定位。在几次湖上和海上试验中,利用“超同步周期”水声定位技术对远距离水声目标进行定位,都取得了令人满意的结果。 相似文献
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水声应答器(Acoustic Transponder/Responder)是一类常用的水声设备,主要功能是完成水下设备的定位和导航,广泛应用在水声系统测试、目标模拟以及水声科学试验中。本文以NI公司的PCI-6052采集卡和工控机构成信号处理模块,设计出了一种可灵活配置的水声应答系统(ESRAE,Extensible Sound Responder for Acoustic Experiments),通过环境噪声电平的跟踪估计和脉冲判决技术实现了复杂海洋条件下脉冲检测、回发功能,并在海洋水声信道测量试验中得到了成功的应用。 相似文献
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Ling J He H Li J Roberts W Stoica P 《The Journal of the Acoustical Society of America》2010,128(5):2898-2909
Low probability of detection (LPD) communications are conducted at a low received signal-to-noise ratio (SNR) to deter eavesdroppers to sense the presence of the transmitted signal. Successful detection at intended receiver heavily relies on the processing gain achieved by employing the direct-sequence spread-spectrum (DSSS) technique. For scenarios that lack a sufficiently low SNR to maintain LPD, another metric, referred to as low probability of interception (LPI), is of interest to protect the privacy of the transmitted information. If covert communications take place in underwater acoustic (UWA) environments, then additional challenges are present. The time-varying nature of the UWA channel prevents the employment of a long spreading waveform. Furthermore, UWA environments are frequency-selective channels with long memory, which imposes challenges to the design of the spreading waveform. In this paper, a covert UWA communication system that adopts the DSSS technique and a coherent RAKE receiver is investigated. Emphasis is placed on the design of a spreading waveform that not only accounts for the transceiver structure and frequency-selective nature of the UWA channel, but also possesses a superior LPI. The proposed techniques are evaluated using both simulated and SPACE'08 in-water experimental data. 相似文献
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文章综述了几种典型结构水声换能器近些年的新发展,包括:弯张换能器、圆柱面辐射型换能器、纵向换能器等等,主要介绍这些结构类型水声换能器的设计新思想和多方面优化改进的新成果。 相似文献
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V. I. Bardyshev 《Acoustical Physics》2003,49(3):285-289
Characteristics of a compensated receiving antenna array consisting of four drifting radioacoustic relaying buoys are studied experimentally. The signal frequency is 21 Hz. The array gain is 11.4 dB, and its noise immunity is 3.8 dB. 相似文献
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Yu. A. Chepurin 《Acoustical Physics》2007,53(3):393-416
Three full-scale experiments on acoustic tomography of the ocean that were carried out under the supervision and with the participation of L.M. Brekhovskikh by researchers from the Shirshov Institute of Oceanology, Russian Academy of Sciences, are described. An attempt is made to combine and generalize the results of three sets of publications devoted to the Norway Sea (1990), THETIS-II (1994), and ACOUS (1998–1999) experiments. 相似文献
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The possibility of obtaining the efficiency of simple disc transducers, broad-banded by use of face-plates, from input electrical conductance measurements under air-loading is explored. For an air-backed ceramic disc with a Perspex face-plate it was found that the main limitation to the accuracy of efficiency estimates is due to departures from uniformity of the face-plate thickness. 相似文献
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Song HC 《The Journal of the Acoustical Society of America》2012,131(4):EL342-EL347
The bidirectional decision feedback equalizer (BiDFE) that combines the outputs of a conventional decision feedback equalizer (DFE) and backward DFE can improve the performance of the conventional DFE by up to 1-2 dB based on simulations. In this letter, the BiDFE concept is extended to multichannel time reversal communications involving a DFE as a post-processor. Experimental data collected in shallow water (10-20 kHz) show that the performance can be enhanced by 0.4-1.8 dB in terms of output signal-to-noise ratio. In particular, a larger improvement (e.g., 1.8 dB) is achieved for time-varying channels where the channel diversity in opposite directions is more profound. 相似文献
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The outer cavity Janus-Helmholtz with sound insulation layer is presented for obtaining the capacity of high-power non-directional transmitting. The radiation efficiency and directivity in the 0 degrees direction can be improved when the radiation mode is changed by laying sound insulation layer. The operating bandwidth can be expanded effectively by the dual mode coupling between the cavity vibration and longitudinal vibration of Janus transducer. A prototype is designed by finite element method. Test results show that the results are in good agreement with the design results. Compared with inner cavity Janus-Helmholtz transducer,acoustic radiation performance of outer cavity Janus-Helmholtz underwater acoustic transducer in the 0 degrees direction has been significantly improved. 相似文献
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为获得具有大功率无指向性发射特性的水声换能器,提出了一种外液腔式Janus-Helmholtz结构。通过设置隔声层改变换能器的声辐射模式,从而改善声辐射效率和无指向性方向的声辐射能力,并利用外液腔振动和Janus换能器纵向振动耦合实现宽带发射。基于有限元法设计了一只工作频段为1.1~3.5 kHz的外液腔式Janus-Helmholtz换能器试验样机。样机测试结果显示与设计结果符合得较好,与内液腔式相比,外液腔式Janus-Helmholtz水声换能器在0°方向的声辐射能力得到了显著改善。 相似文献