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A novel window function series in the form of two-term polynomials suitable for narrow mainlobe width applications is described. The mainlobe width of the polynomial series can assume values between /spl plusmn/1/T to /spl plusmn/1.5/T, where T is the window duration and the asymptotic decay can be either 6dB/octave or 12dB/octave depending on the criterion imposed. The polynomial series has the narrowest mainlobe width of all the windows reported so far, with 12 dB/octave decay of sidelobes. It is shown that, theoretically, the series achieves the mainlobe width of a rectangular window while maintaining the higher decay of sidelobes. 相似文献
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基于椭圆球面波函数的最佳窗函数分析 总被引:2,自引:0,他引:2
针对椭圆球面波函数在窗函数中的应用问题,从能量聚集性角度理论证明了椭圆球面波函数(PSWF)是最佳窗函数,采用基于特征值分解的数值算法求解椭圆球面波函数,筒化了求解过程,算法简便,易于实现。通过仿真分析,与现有的窗函数相比,在相同持续时间和边瓣峰值条件下,椭圆球面波窗函数主瓣最窄、能量聚集性最好,频谱分辨率最高。 相似文献
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线性调频信号主瓣不展宽旁瓣抑制方法 总被引:1,自引:0,他引:1
以汉明窗为代表的加权方法在抑制线性调频信号的匹配滤波输出峰值旁瓣的同时展宽主瓣,致使距离分辨力下降。为兼顾旁瓣抑制和高距离分辨力的需求,该文提出一种新的主瓣不展宽旁瓣抑制方法。该方法首先将匹配滤波和加权处理的输出幅度进行归一化处理,然后逐点进行比较,再取各点对应的最小值作为最终的输出数据。该方法兼取了匹配滤波和加权处理的优点,其-3 dB主瓣展宽系数与匹配滤波相比仅为1,而旁瓣抑制性能和对应的加权处理相当。仿真结果和湖上试验验证了该方法的有效性。 相似文献
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在新型的天气雷达中,由于地面杂波反射强度能达到30~55dB,为了测量雨水强度,要求旁瓣电平小于60dB。相对于线性调频信号通过幅度加权得到低旁瓣输出,非线性调频信号(NLFM)无需加权就可以得到很低的主副瓣比,因此没有加权引起的信噪比损失和主瓣展宽等问题。但是对非线性调频信号直接匹配滤波只能获得-40dB左右的主副瓣比,无法满足天气雷达实际应用的需要,因此文中提出一种基于非线性调频信号的改进设计方法,仿真结果表明,该方法可以有效降低旁瓣电平,获得-73dB的主副瓣比,但也会引入一定的信噪比(SNR)损失。 相似文献
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The most common approach to establish a set of window coefficients, representing the discrete time window (data window), is to select a suitable one from the well-known collections of continuous time window functions by simply sampling techniques. The simplicity of this approach has its price in certain complications which become more and more obvious as the number N of window coefficients decreases to small values (N about 20 or less). It can be shown, that the DFT-even sampling technique as proposed by Harris [1] is not the most suitable one. Since both the aliasing effects as well as the relative position of the sampling raster gain influence on the resulting window magnitude spectrum in such a way that they must be checked individually, it turns out to be better to change the whole design strategy. The design of discrete windows is changed into an optimization problem within the set of all potential window coefficient vectors of given dimension. We apply the optimization criterion of Landau and Pollak [9]. One important advantage of this approach is that the optimization of the window coefficients is reduced to the proper selection of one single parameter which in a monotonic manner controls the trade-off between the two relevant window features mainlobe width and sidelobe level. 相似文献
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当发射天线的个数和结构固定且发射方向图所需要的3 dB主瓣宽度较宽时,绝大多数的发射方向图优化设计方法综合得到的发射方向图都会产生主瓣分裂的现象.针对于此,本文提出一种基于主瓣保形的低旁瓣MIMO雷达发射方向图设计方法.该方法通过约束主波束区域内任意两点之间的线段总是在主波束区域的内部来有效地避免主瓣分裂现象,以及利用... 相似文献
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Chi Chang-Yung 《Signal Processing, IEEE Transactions on》1991,39(9):2082-2086
A performance analysis is presented for false alarms, correct detections, and the resolution of the suboptimal maximum-likelihood deconvolution (MLD) algorithm, called the single most likely replacement (SMLR) algorithm. It is assumed that the source wavelet and statistical parameters are given a priori. It is shown analytically that the performance improves as the signal-to-noise ratio (SNR) increases and as the mainlobe width of the normalized autocorrelation function of the source wavelet decreases. For the same performance, a higher SNR is required as the mainlobe width of the normalized autocorrelation function increases. Some simulation results which are consistent with the analytic results are presented 相似文献
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该文提出了任意信号的时域线性伸缩表达式,给出了一类新的雷达波形,并对这类波形的压缩形式(匹配滤波输出)在时域进行旁瓣抑制数字滤波。仿真结果表明,这类波形的距离模糊函数的峰值旁瓣电平可达-18~-20 dB,而4dB主瓣宽度仅为相同参数的线性调频(LFM)压缩信号主瓣宽度的54%~70%;对这类波形的匹配滤波输出用该文改进的数字旁瓣抑制滤波器滤波后,其峰值旁瓣电平可低达-50dB,且主瓣宽度仅为单位采样符号长度。 相似文献
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在机载单通道雷达的运动目标检测中,若雷达相干处理的Dopp ler分辨能力差于主瓣杂波Dopp ler谱宽,在Dopp ler域主瓣杂波无法与慢速目标有效区分,这给运动目标检测带来了很大的困难。文中提出的投影矩阵方法首先在时域将主瓣杂波滤除,然后进行多普勒滤波,由于主瓣杂波被有效抑制,系统对慢速目标的检测能力大大提高。理论推导和仿真实验证明,投影矩阵方法在主杂波之外信噪比损失性能比三脉冲相消方法有明显的改善。 相似文献
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机载雷达欺骗式主瓣干扰不仅会引起大量虚警,还会污染空时自适应处理(STAP)器的训练样本,引起自适应方向图畸变,导致期望信号相消和杂波抑制性能下降。针对此问题,利用目标信号与干扰信号极化特性的差异,该文提出一种极化-空域联合自适应波束形成的方法来抑制欺骗式主瓣干扰。该方法首先在多普勒清晰区挑选干扰样本,并采用特征融合技术估计干扰协方差矩阵,然后采用重叠滑窗的子阵合成方式进行极化-空域联合自适应波束形成,在抑制主瓣干扰的同时为后续杂波抑制保留了空域自由度,最后通过STAP抑制剩余的杂波。该算法可以有效滤除密集欺骗式干扰,减少由其引起的虚警,改善机载STAP雷达的杂波抑制性能。仿真结果验证了该方法的有效性。 相似文献