相控阵多普勒计程仪的相控波束接收方案

相控阵多普勒计程仪具有基阵体积小，且无需进行声速补偿等优点，本在讨论相控阵多普勒计程仪原理的基础上，提出了相控接收和宽带系统移相的方案，并通过试验验证了实际设计制作的相控接收系统的可行性。     

SJTU-1型新型医用超声设备声输出测量系统通过鉴定

2003年2月27日由国家药品监督管理局医疗器械司委托全国医用电器标准化技术委员会组织,在上海市举行了SJTU-1型医用超声设备声输出测量系统的技术成果鉴定会。由王威琪院士、冯若教授、张德俊教授为主任委员的鉴定委员会,对此项成果进行了测试和技术鉴定,认为SJTU-1型医用超声设备声输出测量系统的技术指标达到了同类系统的国际先进水平,某些功能优于国外同类系统。     

新型多普勒声雷达

从七十年代开始,声雷达已广泛应用于大气层的探测.它可向气象学家提供有关大气层界面变化过程的重要情报,具有操作方便、机动性和坚固等优点.     

直升机模型旋翼声学试验声信号分析中的抑噪方法研究

将直升机模型旋翼在消声室中进行声学性能测试是研究直升机旋翼噪声特性的一种最有效最直接的方式;在直升机模型旋翼消声室试验中,发现传声器采集到的围绕170 Hz特征频率分布的频带极窄的旋翼声信号上叠加有宽频无用噪声;试验中采集到的声信号信噪比与总距角大小成正比,小总距角时声信号信噪比较小,无用信号成分会掩盖声信号真实信息,必须采用高效的方法去除无用成分并同时最大可能不损坏需要成分;模型旋翼声信号中各成分频带分布不同,信号自相关长度与其分布频带有关,文章指出可以根据信号中各成分之间自相关长度的差异性采用自适应线性预测器把所需信号成分预测分离出来;通过分别对比在总距为0°、6°、10°时声信号与各自处理结果,表明叠加在信号上的无用成分被成功滤除,信号质量得到明显改善。     

我国自主研制的医用超声设备声输出测试系统通过专家鉴定

国家药品监督管理局委托全国医用电器标准化技术委员会,于2003年2月27日主持对上海市医疗器械检验所委托上海交通大学研制的SJTU-1型医用超声设备声输出测量系统,进行了技术鉴定。鉴定会委员审阅了全部有关资料、认真听取了研制组负责人寿文德教授所作的研制报告和测试组提供的测试报告,并现场参观了该测量系统的实际操作与测量。通过认真讨论,取得如下一致鉴定意见。 1 SJTU-1型声输出测量系统的研制成功,对于贯彻超声诊断设备声输出的国家标准(与国际标准同)具有重要意义。     

声表面波Chirp滤波器及卷积器组成的信号谱分析系统

本文报告了两种声表面波(SAW)器件组成的频谱分析系统及其实验结果.使用SAW Chirp滤波器与SAW卷积器组成两种类似的实验系统,进行了连续波信号、调制脉冲信号、以及上述两种信号同时输入的谱分析,还进行了信号加窄带干扰的谱分析.两种系统获得一致的结果.实验表明,这些系统具有8MHz带宽,可分析10μs时宽的信号,其等效滤波器数目等于80.文内给出一些实验照片. 由SAW器件组成的谱分析系统是一种模拟信号处理系统.它具有结构简单、实时、时带积大、体积小、重量轻及功耗低等优点,是七十年代发展起来的,颇受人们的重视.我们在国内首次实现了由SAW Chirp滤波器或/和卷积器组成的两类系统.     

多普勒计程仪作用距离估计

多普勒计程仪已成功应用于多种载体的导航,而其最大作用距离对于设计和使用都具有重要的意义。根据声纳方程各项的定义并根据多普勒计程仪工作时的特点,推导出不同条件下声纳方程中各项的计算公式,从而对多普勒计程仪的最大作用距离进行估计,最后将某型多普勒计程仪的相关参数代入推导的公式中,并进行计算得到理论计算值。同时还计算了多普勒计程仪在不同条件下的作用距离。     

水声信号处理领域新进展

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。     

The characteristics of acoustic line array prototypes for scale model experiments

The sound fields created by three different settings of a 5 m long linear loudspeaker array were studied experimentally in the present investigation in an attempt to find out a method to produce a reasonable sound field for scaled down model experiments. The first setting was with all the loudspeakers facing vertically upward, while the second setting was with all the loudspeakers facing the horizontal. The last one resembled the first setting but the loudspeakers were put inside a small partial enclosure whose opening was facing vertically upward. Results show that the last setting can produce a sound field with characteristics close to those of a two-dimensional sound field. The second setting results in a sound directivity pattern relevant to that of the measured A-weighted traffic noise.     

Observer-based beamforming algorithm for acoustic array signal processing

In the field of noise identification with microphone arrays, conventional delay-and-sum (DAS) beamforming is the most popular signal processing technique. However, acoustic imaging results that are generated by DAS beamforming are easily influenced by background noise, particularly for in situ wind tunnel tests. Even when arithmetic averaging is used to statistically remove the interference from the background noise, the results are far from perfect because the interference from the coherent background noise is still present. In addition, DAS beamforming based on arithmetic averaging fails to deliver real-time computational capability. An observer-based approach is introduced in this paper. This so-called observer-based beamforming method has a recursive form similar to the state observer in classical control theory, thus holds a real-time computational capability. In addition, coherent background noise can be gradually rejected in iterations. Theoretical derivations of the observer-based beamforming algorithm are carefully developed in this paper. Two numerical simulations demonstrate the good coherent background noise rejection and real-time computational capability of the observer-based beamforming, which therefore can be regarded as an attractive algorithm for acoustic array signal processing.     

声矢量传感器阵宽带相干信号子空间最优波束形成

提出了基于矢量传感器阵的宽带相干信号子空间最优波束形成。建立了矢量传感器阵的宽带阵列信号模型,将宽带聚焦思想引入到了矢量传感器阵宽带处理,证明了矢量传感器阵与声压传感器阵宽带聚焦矩阵之间的关系,为矢量传感器阵宽带聚焦矩阵的构造提供了一种方法。推导了基于矢量传感器阵宽带最优波束形成的空间谱,通过空间重采样方法实现矢量传感器阵宽带聚焦,避免了对目标源方位的预估。通过仿真验证了矢量传感器阵具有更优越的性能:可以解宽带相干源;能够实现全空间无模糊定向;可以空间欠采样,因而在不增加计算量的基础上,能够提高阵列处理的性能;克服了传统声压传感器线阵端射方向上,目标方位估计性能下降的缺点。     

A Jump-U model of echo pattern for a sonar ranging module

Sonar is extensively used in robot as a range sensor and the time-of-flight (TOF) information of ultrasonic echo is frequently adopted in sonar applications. This paper proposes a Jump-U model of ultrasonic echo pattern based on TOF data for a sonar ranging module. The model is established through a data regression method, utilizing TOF data and the relation between the delay time and the bearing angle of the sensor as input parameters. Because the proposed model can explain the jump phenomenon of TOF data and the shape of TOF data is similar to character U, the model is named as Jump-U. Moreover, the model includes several parameters, and one of them is intensity factor which can be regard as a relative strength of ultrasonic echo. Experiments are conducted to verify the proposed model by measuring the echo’s TOF data of a plane with distances ranging from 100 to 200 cm. The results show a close agreement between simulation and measurements.     

Highlight model of echoes from sonar targets

I.IntroductionTheecho-rangingapproachistheonlycffectiveapproachfordetectionandidentifi-cationofunderwatertargetifitisasilcntobkct.Echoformationisaphysicalprocessinwhichthetargetisexcitcdbyincidentwavc.Byechothecharactcristicinformationsoftargethavebcencarricd.Suchinformationsarejustfundamentalsofdetectionandiden-hficationappliedbyactivesonars.Classificationandidentificationareimportantdevelopmentsofreccntsonarsin-c1udingthehomersoftorpedocs.Thisneedsadecpunderstandingrcferredtoechobe-haviors…     

适用于声呐阵形估计的姿态传感器网络设计

设计了一种基于姿态传感器网络的声呐阵形估计系统,给出了系统设计的整体方案并对系统的软硬件设计进行了论述。实验结果证明了该设计的可行性。     

A model for estimating the signal from an acoustic emission source

A model for calculating acoustic emission amplitudes is presented. The model is based upon a method of describing the stress waves from a local change of an inelastic strain. The model takes into account the limitations of normal measuring equipment. A numerical example is given.This work presents a method that gives a possibility to correlate the measured ae amplitude with the magnitude of the physical event with in the material.     

Insertion loss of sound waves through composite acoustic window materials

This study evaluated the insertion loss of sound waves through composite acoustic window materials for sonar dome applications, and examined the influence of dome shape on the sonar performance. The insertion loss of sound waves through acoustic window materials was experimentally measured as a function of frequency at normal incidence. The insertion loss was also theoretically estimated with three- and four-medium layer models. The theoretical estimation of insertion loss showed good agreement with the experimental measurements. The insertion loss was also measured as a function of angle of incidence. The characteristics of longitudinal and converted shear waves were observed at various angles of incidence. This study will be useful to select acoustic window materials with the appropriate acoustic characteristics for practical sonar dome applications.