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针对水下探测系统探测船舶磁场信号时信噪比较低的问题,首先根据磁异常信号的频域特征,设计了约束最小二乘FIR滤波器,通过对含噪信号进行带通滤波,滤除高频噪声;再采用BP神经网络对低频分量进行学习,提取船舶目标特征信号。将该算法应用于船模实测实验,结果表明:该算法可以显著提高信噪比,增强对船舶磁场信号的检测能力。 相似文献
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基于CZT的频谱细化算法及应用 总被引:1,自引:0,他引:1
针对复杂信号频域特征提取问题,利用Delphi语言编写了Zoom-FFT和基于CZT的频谱细化方法应用软件,以某型坦克传动箱振动速度信号为例进行了对比分析,验证了算法的有效性和程序设计的正确性。结果表明:基于CZT的频谱细化方法具有运算效率高、细化效果好等优点,可以在复杂信号分析中推广应用。 相似文献
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导航信号模拟器需要模拟电离层引起的延时和色散效应,与传统导航信号相比,新体制高阶BOC信号具有更宽的带宽,而传统导航信号的模拟方法会引入不可忽略的电离层延迟建模误差。通常情况下BOC(14,2)信号上下边带信号的电离层延迟可达到米级的差异。提出运用双边带模型的BOC信号模拟方法并进行了仿真,结果表明改进方法可以准确模拟电离层色散效应的影响。 相似文献
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The Signal‐to‐Interference‐plus‐Noise Ratio (SINR) is an important metric of wireless communication link quality. SINR estimates have several important applications. These include optimizing the transmit power level for a target quality of service, assisting with handoff decisions and dynamically adapting the data rate for wireless Internet applications. Accurate SINR estimation provides for both a more efficient system and a higher user‐perceived quality of service. In this paper, we develop new SINR estimators and compare their mean squared error (MSE) performance. We show that our new estimators dominate estimators that have previously appeared in the literature with respect to MSE. The sequence of transmitted bits in wireless communication systems consists of both pilot bits (which are known both to the transmitter and receiver) and user bits (which are known only by the transmitter). The SINR estimators we consider alternatively depend exclusively on pilot bits, exclusively on user bits, or simultaneously use both pilot and user bits. In addition, we consider estimators that utilize smoothing and feedback mechanisms. Smoothed estimators are motivated by the fact that the interference component of the SINR changes relatively slowly with time, typically with the addition or departure of a user to the system. Feedback estimators are motivated by the fact that receivers typically decode bits correctly with a very high probability, and therefore user bits can be thought of as quasipilot bits. For each estimator discussed, we derive an exact or approximate formula for its MSE. Satterthwaite approximations, noncentral F distributions (singly and doubly) and distribution theory of quadratic forms are the key statistical tools used in developing the MSE formulas. In the case of approximate MSE formulas, we validate their accuracy using simulation techniques. The approximate MSE formulas, of interest in their own right for comparing the quality of the estimators, are also used for optimally combining estimators. In particular, we derive optimal weights for linearly combining an estimator based on pilot bits with an estimator based on user bits. The optimal weights depend on the MSE of the two estimators being combined, and thus the accurate approximate MSE formulas can conveniently be used. The optimal weights also depend on the unknown SINR, and therefore need to be estimated in order to construct a useable combined estimator. The impact on the MSE of the combined estimator due to estimating the weights is examined. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004 相似文献
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利用水下声信号在水表面引起的水表面横向微波振幅很小的条件,将普遍的流体力学方程线性化,推导出在水下点声源的激励下,水表面产生的二维横向微波色散关系以及波的传播形式。结果表明,二维水表面的横向微波具有和一维情况类似的结果,即具有波长短、传播速度小的特点,因而可以对入射到表面的激光束进行调制,为水下声信号检测奠定了理论基础。 相似文献
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The paper presents the possibilities of, and methods for, acquiring, analysing and processing optical signals in order to recognise, identify and counteract threats on the contemporary battleground. The main ways electronic warfare is waged in the optical band of the electromagnetic wave spectrum have been formulated, including the acquisition of optical emitter signatures, as well as ultraviolet (UV) and thermal (IR) signatures. The physical parameters and values describing the emission of laser radiation are discussed, including their importance in terms of creating optical signatures. Moreover, it has been shown that in the transformation of optical signals into signatures, only their spectral and temporal parameters can be applied. This was confirmed in experimental part of the paper, which includes our own measurements of spectral and temporal emission characteristics for three types of binocular laser rangefinders. It has been further shown that through simple registration and quick analysis involving comparison of emission time parameters in the case of UV signatures in “solar-blind” band, various events can be identified quickly and faultlessly. The same is true for IR signatures, where the amplitudes of the recorded signal for several wavelengths are compared. This was confirmed experimentally for UV signatures by registering and then analyzing signals from several events during military exercises at a training ground, namely Rocket Propelled Grenade (RPG) launches and explosions after hitting targets, trinitrotoluene (TNT) explosions, firing armour-piercing, fin-stabilised, discarding sabots (APFSDS) or high explosive (HE) projectiles. The final section describes a proposed model database of emitters, created as a result of analysing and transforming the recorded signals into optical signatures. 相似文献
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欧钢 《国防科技大学学报》2001,23(1):66-72
流水时序调度是专用数字信号处理器高层综合中的一个困难而急待解决的问题 ,文中提出了一种有着鲜明物理意义的归一化定时数据流图 ,基于节点移动研究了合法流水调度变换的内部机理 ,从而证明从任一合法的初始流水调度出发 ,通过合法的节点移动可以搜索到设计空间中任何一个合法的流水调度。一个合法、完备的变换集 ,为寻优搜索的算法应用于流水调度解决了理论和算法实现问题。文中还给出了一些实验结果。 相似文献