基于MATLAB软件的组网LPI雷达系统仿真

LPI雷达以其隐蔽性好而被广泛地应用在军事领域,随着网络中心战的飞速发展,多部LPI雷达可以联网组成一个庞大的雷达系统,其在网络对抗体系中为所有作战阶段提供秘密的监视能力和高度态势感知能力上发挥了及其重要的作用。为了更好的评估组网LPI系统的性能,本文首先对组网LPI雷达系统的总SNR进行推导计算,在此基础上用MATLAB软件对多部LPI雷达系统进行仿真,验证了组网雷达相比无组网配置雷达的优越性。     

Noise variance estimation based on dual-channel phase difference for speech enhancement

In this paper, we propose a method for estimating a signal-to-noise ratio (SNR) in order to improve the performance of a dual-microphone speech enhancement algorithm. The proposed method is able to reliably estimate both a priori and a posteriori SNRs by exploring a direction-of-arrival (DOA)-based local SNR that is defined by using spatial cues obtained from dual-microphone signals. The estimated a priori and a posteriori SNRs are then incorporated into a Wiener filter. Consequently, it is shown from an objective perceptual evaluation of speech quality (PESQ) comparison and a subjective listening test that a speech enhancement algorithm employing the proposed SNR estimate outperforms those using conventional single- or dual-microphone speech enhancement algorithms such as the Wiener filter, beamformer, or phase error-based filter under different noise conditions ranging from 0 to 20 dB.     

Adaptive filtering of EEG/ERP through Bounded Range Artificial Bee Colony (BR-ABC) algorithm

In this paper, the Artificial Bee Colony (ABC) algorithm is applied to construct Adaptive Noise Canceller (ANC) for electroencephalogram (EEG)/Event Related Potential (ERP) filtering with modified range selection, described as Bounded Range ABC (BR-ABC). ERP generated due to hand movement is filtered through Adaptive Noise Canceller (ANC) from the EEG signals. ANCs are also implemented with Least Mean Square (LMS) and Recursive Least Square (RLS) algorithm. Performance of the algorithms is evaluated in terms of Signal-to-Noise Ratio (SNR) in dB, correlation between resultant and template ERP, and mean value difference. Testing of their noise attenuation capability is done on contaminated ERP with white noise at different SNR levels. A comparative study of the performance of conventional gradient based methods like LMS, RLS, and ABC algorithm is also made which reveals that ABC algorithm gives better performance in highly noisy environment.     

提高工业数字射线图像对比度及信噪比的工艺措施

对比度及信噪比是构成工业射线数字图像质量的核心要素。从人眼的视觉特性入手,计算验证了人眼对灰度的分辨能力,在数字射线探测器接收特性基础上总结了图像对比度及信噪比与曝光参数的关系,据此提出了一种提高工业数字图像对比度及信噪比的工艺措施。可供优化数字式射线实时成像检测工艺（RTR）及配置检测设备时参考和应用。     

基于小波变换对GPS信号去噪的分析

小波分解能够精细地把信号划分到不同的频带范围内,因此可对含噪信号在不同频带范围内的特征进行信噪分离.本文从GPS精密测量、导航领域的信号去噪角度,探讨了基于小波分析的信噪分离方法,并结合具体实例,说明小波分析对GPS信号消噪处理的实用性及有效性.     

跨区域CORS系统基准站选址测试数据处理与分析研究

讨论了跨区域CORS系统建设过程中基准站站址测试数据处理的流程与方法,提出了从观测数据完好性、数据质量、单点定位结果以及基线解算等四个方面对CORS系统基准站选址进行分析与评价,并结合武汉城市圈CORS系统建设的实例进行分析.通过实测数据的处理,表明本文提出的CORS系统站址测试数据处理方法能够较客观地反映基准站的观测...     

高精度可变面元三维地震勘探与实践

可变面元三维地震观测系统采用了不同于常规三维观测系统的参数,可形成不同尺寸的面元资料。松辽盆地南部十屋断陷四五家子—八屋地区断裂系统发育,小断层较多。为了提高破碎小断层的成像精度,采用可变面元观测系统进行地震资料采集。在地震资料处理中,采用了层析静校正、多域去噪、地表一致性反褶积、CMP重排与基准面重新计算和叠前时间偏移等关键技术。对松辽盆地南部四五家子—八屋地区高精度可变面元三维地震资料进行了分析、处理和解释,解决了该区特殊的地质问题,取得了好的勘探成果。     

基于相控理论的炮点组合设计技术

在复杂地表区地震勘探中,广泛应用炮点组合激发消除干扰,提高单炮记录的品质。二维相控震源的排列长度和三维相控震源的组合面积决定了定向地震波束的宽度,即地震波能量的定向聚焦状态。本文借用军工领域的相控理论,通过组合激发的时间或深度控制实现相位组合控制,设计合理的组合激发模式,将发散传播的地震波集中于某个方向,即激发定向地震波束,使观测系统接收的反射信号增强,所采集资料的信噪比提高,从而有效地改善了地震勘探效果。     

基于APD的“猫眼”目标主动探测系统信噪比分析

信噪比是表征激光主动探测系统性能的重要指标,通过分析雪崩光电二极管(APD)的噪声来源和离焦“猫眼”目标回波功率,建立了APD探测器的信噪比模型,分析了离焦量、目标距离、激光发散角对APD探测器信噪比的影响,并进行了数值模拟分析,结果表明:离焦量的增大会引起“猫眼”目标回波功率变小,进而使APD探测器信噪比减小;“猫眼...     

基于时域和空域混合的低信噪比视频降噪算法及其分析

论述了几种基于时域和空域混合的对低信噪比视频图像进行降噪处理的算法.考虑单独使用时域或空域降噪算法对视频图像进行处理的缺点和不足.在时域上,由于视频图像帧与帧之间有较强的相关性,采用递归加权算法;在空域上,分别采用第二代Curvelet变换理论的Wrap算法( Wrapping-Based Transform)、全变差...