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通过推导得出了存在载波频差时,有数据辅助时对PSK信号进行载波相位估计时的最佳观测长度,并得到了最佳观测长度下的载波相位估计方差,最后通过仿真对理论分析结果进行了验证。研究成果可以为突发通信系统中的信号设计及同步算法的设计提供依据。 相似文献
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相比传统的两步定位方法,以Weiss和Amar等人提出的目标位置直接确定方法具有定位精度高、目标分辨率高、可避免"目标-量测"匹配等优势.本文基于该类定位方法的思想,提出了一种利用单个运动天线阵列对目标辐射源的直接定位算法.与已有直接定位算法不同的是,文中新算法考虑了阵列互耦的影响,并且能够实现阵列互耦参量和目标位置参量的解耦合估计.此外,文中还基于矩阵特征值扰动理论,定量推导了新算法参数估计的理论方差(包括目标位置估计方差和互耦向量估计方差),并且给出了全部参量估计方差的克拉美罗界.最后,该文通过仿真实验验证了新算法的优越性和理论分析的有效性. 相似文献
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两维自聚焦是高机动条件下机载合成孔径雷达(SAR)高分辨率成像的重要保障。现有的双基SAR两维自聚焦算法没有充分利用相位误差的先验结构信息,是对相位误差的一种盲估计,在计算效率和参数估计精度方面仍然存在很大限制。该文从双基SAR极坐标格式成像算法新解释入手,从残留距离徙动(RCM)校正的观点出发,将极坐标格式(PFA)算法的实现解释为距离频率和方位时间两个变量的解耦过程。利用这一观点分析了极坐标格式算法中的距离和方位重采样对两维相位误差的影响,揭示了残留两维相位误差固有的解析结构。基于这一固有的先验信息,该文提出了一种结合先验信息和图像数据的双基SAR两维自聚焦算法。算法通过引入先验知识,将两维相位误差估计降维成一维方位相位误差的估计;同时,在估计方位相位误差时,通过多子带数据平均,充分挖掘了所有数据的信息。相比于已有算法,无论是参数估计精度还是计算效率都有明显改善。实验结果验证了该文理论分析的正确性以及所提两维自聚焦方法的有效性。 相似文献
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具有良好宽容性的逆波束形成干扰抑制算法研究 总被引:2,自引:0,他引:2
在阵列信号处理中,逆波束形成干扰抑制算法利用干扰的方位信息估计干扰信号从而进行干扰抑制,但在复杂海洋环境中阵列接收的干扰信号往往存在相位随机扰动,此方法估计的干扰信号与实际干扰信号有较大偏差,造成干扰抑制效果不理想。为适应干扰相位的随机扰动,具有良好宽容性的逆波束形成干扰抑制算法充分考虑随机扰动的存在,利用干扰重建矩阵估计干扰信号,此时估计干扰信号更接近实际干扰信号,保证干扰抑制有较好的结果。该文算法充分考虑了复杂海洋环境中干扰信号的相位扰动,可以获得较好的干扰抑制效果,提高了算法的宽容性。理论分析、计算机仿真结果均表明该文算法的有效性。 相似文献
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A novel random phase updating algorithm for reducing the peak-to-average power ratio (PAPR) of OFDM signals is addressed. The phase of each subcarrier is updated by a random increment until the PAPR goes below a certain threshold level. We investigate the influence of different distributions for the phase increments and the variance of distributions on the mean and variance of PAPR as well as the number of iterations to reach the threshold. Further, the random phase updating algorithm has been extended by dynamically reducing the threshold level. After successful updating of the phase shifts, the threshold level is reduced and the variance of the phase increments is changed. Simulation results of the algorithm are provided. It is shown that the random phase updating algorithm with dynamic threshold gives the best results and can reduce the mean power variance of an 8-carrier OFDM signal with BPSK modulation by a factor of 7 dB. In order to reduce the complexity, the random phase updating algorithm is investigated with quantization and grouping of the phase shifts. Results show that for a 16-carrier OFDM system, 2-level quantization of phase shifts in 8 groups of 2 carriers give no significant increase in the power variance while reducing complexity. Further, the impact of phasing on the bit error rate performance of the OFDM system is studied. 相似文献
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Pooi Yuen Kam Keng Hong Chua 《Electronics letters》1997,33(19):1603-1604
The phase estimation error variance of an adaptive, digital, coherent PSK receiver is analysed in the steady-state at high SNR. It is shown that, because of the risk function chosen in the gain adaptation algorithm of the phase estimator, the phase error variance is minimised 相似文献
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To overcome the invalid phase and phase jump phenomenon generated during the phase unwrapping, a phase error correction method based on the Gaussian filtering algorithm and intensity variance is proposed in this paper. First, a threshold of fringe intensity variance is set to identify and clear the phase in the invalid region. Then, the Gaussian filtering algorithm is employed to correct the phase order at the fringe junction, and then the absolute phase is corrected. Finally, the phase correction experiments of different geometric objects are carried out to verify the feasibility and accuracy of the proposed method. The method proposed in this paper can be extended to the correction of absolute phase error obtained by any coding method. 相似文献
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为了降低多天线信号频谱偏移、相位随机性和噪声的不均匀性、不确定性对频谱感知性能的影响,该文利用接收信号协方差矩阵主对角线包含主用户的主要信息,以及协方差矩阵元素的平均方差反映元素波动程度的特点,构造对角线元素绝对值的平方和与其平均方差之比的频谱感知的检验统计量,推导了该统计量服从的概率分布函数,给定虚警概率,得到判决门限。加性高斯白噪声信道和瑞利衰落信道下的仿真结果表明:本文算法性能优于局部方差法,随着接收天线数和采样点数增加,本文算法性能提升大于局部方差法。 相似文献
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在斜视成像模式下,合成孔径雷达回波信号的距离向和方位向之间存在严重的相位耦合效应,影响高分辨聚焦.非线性调频变标(NCS)算法在二维频域进行三次相位滤波,并补偿二次距离压缩(SRC)随距离的线性变化,在一定程度上改善了斜视成像的聚焦性能.但随着斜视角的进一步增大,三次以上的高阶相位以及SRC随距离的非线性变化对高分辨聚焦的影响也逐渐加大,从而降低成像性能.文中提出基于回波四次相位多项式模型的改进NCS算法,该算法通过两维频域中的三次及四次相位滤波以补偿参考距离处的相位耦合项,并且考虑了SRC随距离的非线性变化对聚焦的影响.通过仿真及实测数据的成像效果验证了该方法的可行性及有效性. 相似文献
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In detecting weak signals based on the Duffing oscillator, it is usually assumed that the frequency is known, which is not always the case. This paper studies the problem of detecting the frequency of the to-be-detected weak signal based on the Duffing oscillator. For this purpose, the variance of the Duffing oscillator’s output is exploited, which has the property of multi-extremum single-maximum (MESM) distribution with the frequency of the periodic signal. The impact of signal’s phase on the MESM distribution is discussed. When the signal’s phase is known, the frequency of the signal can be directly identified as that with the maximal variance, which leads to a nonlinear optimization problem that can be solved by a particle swarm optimization (PSO) algorithm. When the phase is unknown, the π/2-phase-shift method is to be exploited integrated with a PSO algorithm. It is shown that the frequency can be precisely and efficiently identified by this method, whose effectiveness is verified by simulation results in Matlab. 相似文献
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基于小波变换的加权最小二乘相位解缠算法 总被引:2,自引:0,他引:2
提出了一种求解加权最小二乘相位解缠问题的新算法,采用相位导数方差相关图定义了相位数据的初始权重,给出了利用多分辨率小波变换进行相位解缠的具体实现方法.利用离散小波变换,将原线性系统转化成具有较好收敛条件的等价新系统,通过独立求解新系统中的低频部分,加快了系统的收敛速度.仿真实验表明:该算法具有收敛速度快、解缠效果好等特点. 相似文献
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针对通道幅相误差和图像配准误差等非理想因素导致地面动目标检测性能下降的问题,该文结合最小方差和空域导向矢量两种杂波抑制算法,提出一种基于通道误差校准的空域导向矢量杂波抑制方法。该方法首先计算最小方差杂波抑制的权向量,通过该权向量构造配准图像,然后利用配准图像计算杂波正交补空间,最后通过正交子空间的方法实现杂波抑制。理论分析及实验结果表明,所提方法在图像配准误差和通道幅相误差较大的情况下仍具有很好的检测性能,能获得较最小方差杂波抑制方法和基于空域导向矢量的杂波抑制方法更高的信杂噪比。 相似文献
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CHRISTIAN BERGOGNE PHILIPPE SEHIER MICHEL BOUSQUET 《International Journal of Satellite Communications and Networking》1996,14(6):455-465
In burst transmission, carrier recovery is a critical point for synchronization systems. With a feedforward carrier phase recovery algorithm, a small frequency offset can significantly increase the cycle slip rate and then the phase error variance. Therefore, in order to obtain an accurate carrier phase estimation, a precise frequency correction is required. For M-states phase shift keying (M-PSK) modulated signals an unbiased feedforward reduced complexity frequency estimator (RCFE), operating in the non-data aided mode (NDA) is derived from the maximum likelihood (ML) principle. A compromise is realized between noise filtering and estimation slip probability by minimizing the estimator variance. It is optimized to operate at a low signal-to-noise ratio and short bursts. Its performance is compared to that of the ML estimator. The estimator is applied to an all-feedforward synchronization structure with QPSK modulated signals. Global performance of the modem synchronization structure is supplied. © 1996 by John Wiley & Sons, Ltd. 相似文献