共查询到19条相似文献,搜索用时 343 毫秒
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在研究R.Klemm博士的级联抑制噪声干扰和杂波算法以及旁瓣对消算法的基础上,针对噪声干扰和地杂波同时存在的情况,提出了一种采用旁瓣对消结构级联抑制干扰和杂波的算法。该算法首先利用相控阵天线合成一个辅助天线和多个主天线,多个主天线共用一个辅助天线,针对每一对主辅天线,采用旁瓣对消算法在空域抑制噪声干扰;然后对多个主天线的输出结合时域进行STAP(空时二维信号处理)抑制地杂波。并且证明了该级联结构等效于一种同时抑制干扰和杂波的结构。计算机仿真结果及性能分析验证了该算法能有效地抑制干扰和杂波,且与其他级联结构相比,所提出的结构更利于工程实现。 相似文献
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基于一个高频双极化雷达系统,给出了一种利用辅助水平天线抑制Es层干扰的自适应系统.水平极化天线接收的数据与垂直极化天线接收的数据进行相关,自适应的估计出垂直天线接收中的干扰,然后对消掉它们.干扰对消在每个相参积累周期后进行.实际数据对消后的信噪比可以提高到25dB. 相似文献
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提出了两种新的抑制Es层杂波的自适应对消算法,分别是频域瞬时值LMS算法和归一化频域瞬时值LMS算法。频域瞬时值LMS算法是利用辅助天线输出的Es层杂波瞬时值来估计主天线当前输出中的Es层杂波成分,可以更大程度上抑制Es层杂波。而归一化频域瞬时值LMS算法则是在频域瞬时值LMS算法的基础上增加归一化的过程,可以大大缩短自适应过程的收敛时间。 相似文献
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旁瓣对消器形式的自适应性应用于旋转雷达天线时,要求所采用的自适应权值以足够高的速率更新,避免由于主波束移动而引起性能下降。本文描述了采用混合模/数解法实验旁瓣对消器的设计方法和性能。专用数字处理机采取开环算法来计算权值,并通过乘法数模变换器把结果应用到模拟信号通路。选择开环算法,是为了避免与闭环旁瓣对消方法有联系的收敛性问题。本文有一节谈的是实验系统的调定技术。介绍了实验结果,其中包括一些有效地利用动目标显示滤波器把采样的杂波污染减少到最小的试验。结果表明,利用旁瓣对消,经过雷达天线23分贝旁瓣进来的干扰,至少减少了大约12分贝。本文还发表了有关采样量和权值更新频率影响对消性能的数据。 相似文献
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旁瓣对消技术是应对旁瓣有源压制干扰的有效手段。实际应用发现,对于工作在具有强杂波环境的中近程雷达,指向杂波区域的回波数据中会存在大量乃至全距离的杂波数据,对干扰样本的选取带来了极大困难。错误选取强杂波数据作为干扰样本不仅难以有效对消干扰,还可能对检测目标的回波造成恶劣影响。本文提出一种基于相关性的杂波环境自适应旁瓣对消方法,首先统计辅助波束与主波束之间的干扰相关性,然后根据相关性统计结果采取不同的对消处理措施,仿真试验平台的试验数据表明本文方法不仅可以在强杂波环境下有效提取样本进行对消处理,而且保障了弱杂波环境下的对消性能,较大地提高了旁瓣对消方法在杂波环境下的适用性。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1968,14(5):734-743
This paper considers the joint optimization of a class of radar signals and filters in a number of clutter-pins-noise environments. The radar signal processor in this case will be optimum in the sense that its output at the time of target detection yields the maximum ratio of peak signal power to total interference power. If the interference at the input to this signal processor is a Gaussian random process, this processor also yields the maximum probability of detection for a given value of false-alarm probability. The signals used are pulse trains and the filters are tapped delay lines. The purpose of signal design is to determine the optimum complex weighting for each pulse of the pulse train. Filter design yields the optimum complex weighting for the output taps of the delay line. Filter design for a specified signal is considered first. This is followed by combined signal and filter design and matched filter design. Constrained signal and filter design is investigated last. It should be emphasized that the optimizations require a knowledge of the clutter time-frequency distribution. For practical situations, when the clutter distribution is unknown, an adaptive filter is proposed that automatically provides the optimum filter weights for a given transmitted signal. When the clutter has a range-time extent less than the equivalent range-time extent of the signal, filter design alone yields nearly optimum performance. As the clutter becomes extended in range-time, it is necessary to consider jointly the design of signal and filter to obtain an optimum radar signal processor. In this report it is suggested that the signal be designed under the assumption of the clutter being extended over a broad range of Dopplers and that the signal processor consist of a bank of adaptive filters. Then each filter output yields the maximum ratio of peak signal to total interference power for this signal design. 相似文献
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Xin Guo Hongbo Sun Tat Soon Yeo 《Geoscience and Remote Sensing, IEEE Transactions on》2008,46(7):1879-1891
The performance of high-frequency surface wave radar (HFSWR) is known to suffer from external environmental interference and noise, such as cochannel radio-frequency interference from other radiating source, ionospheric clutter, lightning impulsive noise, etc. This paper experimentally evaluates the interference cancellation performance of various adaptive beamforming schemes with respect to the aforementioned three types of interferences in an attempt to find the most promising adaptive cancellation scheme in practical HFSWR environment. 相似文献
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高频地波雷达(High Frequency Surface Wave Radar,HFSWR)能够探测视距外的海上目标和超低空飞行器,但其性能通常被电离层杂波严重影响。该文使用一种空域极化域协同滤波算法用于电离层杂波抑制。针对其中电离层杂波空域和极化域参数的估计问题,在距离-多普勒域上利用基于压缩感知(Compressive Sensing,CS)的DOA测角方法进行空域参数估计,并提出一种基于统计特性的极化参数估计方法完成极化参数估计。这两种估计方法可获得更高的参数估计精度,从而提高了电离层杂波空域极化域抑制方法的性能。某HFSWR系统实测数据处理结果表明了参数估计和电离层杂波抑制方法的有效性。 相似文献
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Clairvoyant and adaptive signal detection in non-Gaussian clutter:a data-dependent threshold interpretation 总被引:1,自引:0,他引:1
This paper addresses the problem of signal detection in correlated non-Gaussian clutter modeled as a spherically invariant random process. The optimum strategy to detect a constant signal, with either known or unknown complex amplitude, embedded in correlated Gaussian clutter is given by comparing the whitening-matched filter output with a fixed threshold. When the clutter is non-Gaussian, the performance of the matched filter sensibly degrades. The optimum strategy is the classical whitening-matched filter output compared with a data-dependent threshold. This interpretation provides a deeper insight into the structure of the optimum detector and allows us to single out a family of suboptimum detectors based on a polynomial approximation of the data-dependent threshold. They are easy to implement and have performance that is really close to the optimal. The adaptive implementation of the polynomial detectors is also investigated, and their performance is analyzed by means of Monte Carlo simulation for various clutter scenarios 相似文献
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为了从高频地波雷达(High Frequency Surface Wave Radar, HFSWR)信号生成的复杂距离多普勒(Range Doppler, RD)图像中准确提取运动点目标, 提出了一种基于冗余小波变换(Redundant Discrete Wavelet Transformation, RDWT)的RD图像点目标检测算法.该算法根据点目标与海杂波、电离层杂波等特征的差异, 首先在距离方向进行自适应RDWT以去除海杂波和地杂波, 并在多普勒方向进行自适应RDWT以去除电离层杂波; 然后利用图像形态学运算对背景噪声进行了抑制; 最后进行阈值自适应分割以得到点目标.实验结果表明:该算法能有效抑制RD图像中的海杂波、电离层杂波和背景噪声, 能从复杂的RD图像中实现点目标的有效检测, 其检测性能优于改进的恒虚警率(Constant False Alarm Rate, CFAR)算法. 相似文献
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动目标显示(MTI)技术是雷达在杂波环境中发现运动目标的有效手段。首先讨论了雷达信号处理中常用的自适应动目标显示技术,即在多杂波环境下的自适应杂波抑制技术。然后针对雷达杂波抑制中常用的级联MTI滤波器,提出了一种新的设计方法,即采用时变加权原理,通过对动杂波速度估值,实现对运动杂波抑制滤波器权值的优化。最后给出了这2种杂波抑制级联型MTI的工程实现。 相似文献
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相控阵机载雷达杂波抑制的时—空二维自适应滤波 总被引:37,自引:15,他引:22
本文提出了一种机载预警侧面相控阵雷达抑制地杂波的时-空二维自适应方法,该方法先对各列子阵的数据作多通道的多卜勒滤波,然后分别对相同多卜勒滤波器输出的数据作Capon自适应处理。理论分析和计算机模拟结果表明,本文方法的杂波抑制性能在天线阵元存在一定的随机幅度和相位误差情况下损失不大,对阵元失效也不敏感。 相似文献
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Airborne or spaceborne radar systems often require tests before deployment to verify how well the system detects targets and suppresses clutter and jammer signals. The radar antenna diameter can be large and thus the conventional far-field test distance is impractical to implement. The theory and simulations of phase-focused near-field testing for adaptive phased array antennas is discussed. With near-field source deployment, standard phased-array near-field phase focusing provides far-field adaptive nulling equivalent performance at a range distance of one aperture diameter from the adaptive antenna under test. Both main beam clutter sources and sidelobe jammer sources are addressed. The phased array antenna elements analyzed are one-half wavelength dipoles over the ground plane. Bandwidth, polarization, array mutual coupling, and finite array edge effects are taken into account. Numerical simulations of an adaptive antenna that has multiple displaced phase centers indicate that near-field and far-field testing can be equivalent 相似文献