Focusing transform based robust azimuth angles estimation for wideband signals

A focusing transform based minimum variance method (FTMV) is proposed for estimating the azimuth angles of wideband signals. The estimation error of Direction of Arrival (DOA) in the traditional Minimum Variance (MV) method during the array direction changing with the ship can be eliminated by focusing the sample covariance matrices in wideband onto a single narrowband, and accumulating the beamformer outputs on azimuth. Then, the azimuth angles of signals can be estimated accurately. Experimental results show that the FTMV method is more efficient and robust than the MV method in this case.     

主动声纳方程和传播损失及混响级的定义

A.Ainslie发表文章指出传统定义的被动声纳方程严格应用起来与实际情况存在一定的偏差,某些情况下会带来严重的错误。该偏差需通过接收水听器与声源处介质的特征阻抗比来校正。主动声纳方程中存在同样的问题,其与实际情况的偏差需要用接收水听器与声源处的介质特征阻抗比的平方来校正。本文给出主动声纳方程中传播损失和混响级的重新定义,并且给出相应的两种主动声纳方程,两种方程都消除了这种不期望的特征阻抗比偏差。     

The interference characteristics of platform and towed body noise in shallow water for active/passive towed array sonar

The interference characteristics of towed platform noise resulted from propeller and towed body for active/passive towed array is analyzed. It is shown that, in shallow water environment, the direct wave and bottom/sea surface reflected wave will seriously affect the performance of sonar system. The formula for calculating the direction of arrival (DOA) of interference in terms of various parameters, such as array depth, length of tow cable, is derived. The effect of interference noise for the detection performance of sonar system is described. The results of system simulation provide the method for reducing the effect of these kind of interferences.     

基于改进DPC方法的合成孔径声纳运动补偿研究

合成孔径声纳(Synthetic Aperture Sonar,SAS)成像的难点之一在于声纳基阵载体的不稳定运动影响了合成孔径上水听器接收信号的相干性,其结果将导致图像的畸变和图像分辨率降低。本文在分析基本偏移相位中心(Displaced Phase Centers,DPC)方法的基础上,提出了一种在没有冗余的相位中心而数据在空间的相关性较强时适用的DPC算法。改进的DPC算法能够有效地估计并补偿声纳基阵的侧摆(sway)和偏航角(yaw)导致的运动误差。通过仿真和实验数据验证了算法的有效性。     

一种主动声纳传播衰减补偿设计

主动声纳系统中声信号在海水环境中的衰减对于系统的性能影响很大,对于传播衰减的补偿是提高主动声纳系统性能的手段之一。文章介绍了一种通过声信号的时间增益控制来达到衰减补偿的方法,采用美国analog devices公司的高性能可变增益放大器（VGA）AD605,在前置预处理电路中实现硬件衰减补偿。     

The port/starboard discrimination based on line-spectrum character in towed line array with hydrophone triplets

The energy ratio of broadband signal is utilized for port/starboard discrimination in towed line array with hydrophone triplets in tradition.It works well in most conditions except for two cases:One is low signal to noise ratio(SNR),and the other is that there is a stronger interference lied on the other side of the line array with approximate bearing angles. A method called line-spectrum character extracting is proposed to discriminate port/starboard for these two cases in this paper,and the SNR needed for port/starboard discrimination is reduced significantly.Simulation and the sea-trial data are analyzed to show that the method is stable and valid,and is expected to be applied in real towed line array sonar.A line-spectrum enhancing technology with lower calculation complexity and stable validity is proposed to ensure the application of this method in lower SNR condition.     

基于远近场声传播特性的拖线阵声纳平台辐射噪声空域矩阵滤波技术

针对拖线阵声纳平台噪声构成近场强干扰影响声纳弱目标探测的问题,利用近场平台噪声的多途传播特性及远场目标信号的平面波传播特性,将匹配场定位技术和平面波目标方位估计技术结合,利用平台噪声到达接收阵的拷贝向量以及平面波方向向量共同设计具有强干扰抑制功能的空域矩阵滤波器,实现了近场平台噪声抑制.设计两种最优化问题,获得不同的噪声抑制效果,给出它们的最优解,验证了解的正确性,找出解之间的关联.解释了平台辐射噪声在阵列端首方位附近构成强干扰的原因,同时解释了空域矩阵滤波后存在探测盲区的原因.由仿真可知,空域矩阵滤波处理可获得更小的探测盲区,同时获得盲区外更高的探测能力.     

基于ATmega16控制的新型多功能拐杖

设计了一种由单片机、GSM定位模块、GPS短信模块、语音播放模块、液晶显示屏、温度传感器等组成的老年人用新型拐杖.通过单片机控制GSM短信模块和GPS定位模块,可将老人实时位置信息及时发送给监护人,同时能在设定的时间通过语音芯片给老人以语音提醒.可通过液晶显示屏显示温度和时间,室外温度过高或过低时,语音模块将给予相应的语音提醒.这款拐杖具有安全性高、功能稳定、操作简单、便于携带等特点,是未来拐杖研发的一个重要趋势.     

基于SYN6288的超声波语音测距拐杖的设计

在介绍超声波测距原理的基础上,设计并实现了一种基于SYN6288语音合成芯片的超声波语音测距拐杖。系统以STC89C52单片机为核心,采用高性能的KS103超声波模块,具备温度补偿功能,可以对超声波的速度进行校正。并采用语音合成芯片SYN6288对实时采集的距离信息进行转换,该芯片采用TTS技术,无需预先录音,可以直接实现文字到语音的转换,通过外置扬声器进行语音提示,实现了测量结果的语音化。实验证明,该超声波语音测距拐杖具有较高的精度和使用方便的特点,可为盲人行走提供安全的保障。