共查询到20条相似文献,搜索用时 843 毫秒
1.
基于部分校准极化敏感阵列的信号DOA和极化参数迭代估计 总被引:3,自引:0,他引:3
针对安装于飞机机翼上,具有不同结构极化敏感天线的部分校准阵列,该文提出了一种完全极化电磁波DOA和极化参数的迭代估计方法。该方法基于部分校准阵列,估计阵列误差;然后利用阵列误差,估计单个极化敏感天线的极化导向矢量;最后利用极化导向矢量,估计完全极化电磁波DOA和极化参数。迭代运行上述三步,可以逐步提高估计精度。计算机仿真验证了该方法是收敛的,并且具有良好的鲁棒性。 相似文献
2.
3.
针对基于天线阵列测角的射频识别(Radio Frequency Identification, RFID)定位系统成本高、无法估计目标姿态的问题,提出了一种基于标签阵列的姿态检索的定位算法。首先,分析了天线方向角、标签阵列姿态角和标签阵列信号到达角之间的关系,建立了标签阵列姿态检索的定位模型;其次,对标签阵列中相位误差来源进行了分析,利用标签间的相位差对标签阵列信号进行重构,降低了读写器收发电路、标签电路及多径效应引入的相位误差对定位精度的影响;同时,分析了标签阵列中的互耦效应对相位的影响,提出了互耦效应相位校正方法,提升了标签阵列的测角精度;最后,提出了一种标签阵列姿态估计算法,使用多个天线的方向角实现对标签阵列姿态角估计和定位。实验结果表明,系统在室内环境下平均定位误差为0.2 m,标签阵列的姿态角估计平均误差为4.35°。 相似文献
4.
针对导航应用中阵列天线导向矢量误差导致波束合成器性能恶化甚至失效的问题,提出了一种“北斗”信号重构的导向矢量实时校正算法。该算法利用重构的本地“北斗”参考信号与阵列天线接收信号进行相关解扩处理,然后利用信号子空间与信号正交补空间正交的特性,构造代价函数对各卫星方向的阵列导向矢量进行校正。仿真结果表明,经过校正的导向矢量相位误差从-100°~100°降低到-10°~10°范围内,幅度误差从-10~10 dB降低到-4~2 dB范围内;另外,导向矢量校正后,卫星信号波达方向估计误差在0.2°以内,估计精度大大提高。 相似文献
5.
日益复杂的电磁环境严重干扰了全球卫星导航系统(Global Navigation Satellite System,GNSS)的正常有效运行.多天线空域自适应处理能够有效抑制电磁干扰,但是空域自适应处理算法可能会引入卫星信号载波相位误差.此外,多天线组成的阵列本身存在各种不理想因素也会引入误差,这些对高精度测量系统来说是不可容忍的.为此,本文首先分析了GNSS中常用的空域自适应处理算法在抑制干扰的同时对载波相位测量的影响,在此基础上提出了一种不需要阵列流形信息的盲波束形成算法——二次解重扩算法.其核心思想是在解重扩(De-spread Re-spread,DR)算法的基础上增加频率精估计环节,并根据精估后的载波频率重新构造本地参考信号与接收数据进行相关,从而最小化波束形成权矢量与卫星信号的导向矢量之间的误差,减小了空域抗干扰对卫星信号载波相位的影响. 相似文献
6.
光纤已被广泛研究作为在分布式阵列天线系统中向远程天线传播参考信号的有效手段.分布式阵列天线的一个关键问题是由不同天线接收的参考信号遭受由光纤长度变化以及外部环境变化引起的相位偏差,造成天线间的参考相位不同步.提出一种基于光纤的分布式阵列参考相位稳定方法,基于光纤的反馈回路来监控相位差,使用对称布置在前向通道和反馈通道上的移相器来连续地补偿相位差,实现了天线之间参考相位误差的有效连续补偿.仿真和实测结果表明,所提方法解决了分布式天线阵列光纤长度变化以及外部环境变化引起的相位偏差,当光纤分发10 MHz参考信号时,测试可得分布式天线之间的剩余相位误差小于±0.02°. 相似文献
7.
8.
分组旋转矢量法校正大规模相控阵天线 总被引:5,自引:0,他引:5
基于基本的旋转矢量法,提出了用于大规模相控阵天线校正的分组旋转矢量法.该方法同时旋转多个天线单元的信号源的相位,能够使被测信号的起伏显著增加.误差估计和仿真校正结果显示,该方法能够提高测量精度,改善校正效果. 相似文献
9.
随着对地观测技术的发展,要求SAR系统能够同时实现高分辨率和宽测绘带,天基阵列多通道SAR结合数字波束形成(DBF)技术为解决该问题提供了很好的思路,但各个通道之间相位误差会很大程度上降低DBF的性能,常规通道误差补偿方法估计精度不足,应用场景受限。针对上述问题,该文提出一种基于方向图和多普勒相关系数的天基阵列SAR通道相位误差补偿方法,不仅利用天线方向图先验信息,还充分利用场景不同多普勒相关性信息,通过最小化天线方向图和多普勒的组合差异,实现对通道之间相位误差的估计。结合RADAR-SAT数据的仿真试验结果验证了该算法的有效性。 相似文献
10.
本文针对星载方位多通道高分辨宽测绘带(HRWS)合成孔径雷达(SAR)系统,提出了两种通道相位误差估计方法:信号子空间比较法和天线方向图法.信号子空间比较法基于信号特征向量张成的空间(即信号子空间)与真实导向矢量张成的空间相同这一特性,得到各通道间的相对相位误差,该方法适用范围广,估计精度高,对系统要求低,且运算量小.天线方向图法结合天线方向图,直接估计通道相位误差,无须特征分解,无须矩阵求逆,运算量小,主要适用于均匀分布的场景.最后利用实测地基数据验证了两种方法的有效性. 相似文献
11.
12.
Phase-locked loops (PLL's) may be used to implement signal combiners which coherently sum multiple signals from an array of sensors. In each combiner channel, the sensor signal is simultaneously downconverted to an intermediate frequency (IF) signal and phase-locked to an appropriately generated reference signal by a "long-loop" PLL. This loop maintains a nominal 90° phase difference between the IF signal and the reference signal irrespective of phase of the channel input (sensor output) signal. The channel IF signals are summed to generate the combiner output signal. The reference signal may be a locally generated sine wave or a delayed version of the combiner output signal. Imperfect phase control and, thus, imperfect signal combining results when noise voltages are associated with the channel signals. In this paper, a lincarized model of a PLL coherent combiner is developed. This model applies when the desired channel signals are equal amplitude and angle modulated; the channel noise voltages are equal level, Gaussian distributed, and independent; and the combiner phase errors are appropriately small. This model is then used to derive equations for the variance of differential phase errors associated with combiner operation and to show the effect of these phase errors on the average power in the combiner output signal. Relevant experimental results from a four-channel combiner are compared with the performance predicted by the linear model. 相似文献
13.
共形天线的安装和测量以及载体平台表面的变形和振动均会引起阵元位置误差,严重影响
共形天线的测向性能。通过设置4个方位未知的精确校正的辅助阵元,实现了共形天线大尺度三维
的阵元位置误差校正。给出了阵元位置误差条件下共形天线导向矢量的方位依赖的幅相误差等效
表示模型;基于子空间原理得到等效的方位依赖的幅相误差估计,进而得到共形天线阵元的三维位
置误差估计。该方法可以实现共形天线校正信源来波方位和阵元三维位置误差的联合但“去耦”估
计。计算机仿真结果验证了共形天线阵元位置误差校正的辅助阵元法的有效性 相似文献
14.
现有基于电磁矢量传感器阵列的信号DOA和极化参数联合估计算法,大都假设电磁矢量传感器的三个电偶极子和三个磁偶极子严格指向参考坐标系的三个坐标轴,即不存在原位误差.然而在实际应用场合,电磁矢量传感器是存在原位误差的,因此其实际极化-角度域导向矢量与理想情况下的极化-角度域导向矢量有一定的偏差,导致现有方法的估计性能显著下降,因此必须对原位误差进行校正.通过对存在偏差的极化-角度域导向矢量进行一阶Taylor近似展开,并利用一个辅助校正源,提出了电磁矢量传感器原位误差校正方法,给出了原位误差估计的CRB界.仿真结果验证了该方法的有效性. 相似文献
15.
16.
A Hybrid Frame Concealment Algorithm for H.264/AVC 总被引:1,自引:0,他引:1
In packet-based video transmissions, packets loss due to channel errors may result in the loss of the whole video frame. Recently, many error concealment algorithms have been proposed in order to combat channel errors; however, most of the existing algorithms can only deal with the loss of macroblocks and are not able to conceal the whole missing frame. In order to resolve this problem, in this paper, we have proposed a new hybrid motion vector extrapolation (HMVE) algorithm to recover the whole missing frame, and it is able to provide more accurate estimation for the motion vectors of the missing frame than other conventional methods. Simulation results show that it is highly effective and significantly outperforms other existing frame recovery methods. 相似文献
17.
Robust adaptive array beamforming under steering vector errors 总被引:9,自引:0,他引:9
Cheng-Chou Lee Ju-Hong Lee 《Antennas and Propagation, IEEE Transactions on》1997,45(1):168-175
This paper considers adaptive array beamforming in the presence of random steering vector errors. We first formulate the problem of finding an optimal steering vector as an optimization problem. The cost function to be minimized consists of two terms which utilize a posteriori information due to the received signal data and a priori information due to the probabilistic distribution of steering errors, respectively. Two methods are then presented to find the optimal steering constraint vector. It is shown that each method yields a closed-form optimal solution if the steering error vector is an additive Gaussian random vector. We also investigate the performance for each method. Modification of the proposed methods and an implementation algorithm for dealing with the case of steering vector errors due to phase perturbation are also presented. Finally, several computer simulation examples are presented for illustration 相似文献
18.
A novel cross-correlation based framework is proposed for the problem of blind equalization in communications. We assume that we have access to two observations obtained either by sampling, at the symbol rate, the outputs of two sensors or by oversampling, by a factor of two, the output of a single sensor. In either case, the two observations correspond to the outputs of two channels excited by the same input. The channels are estimated using the theory of signal reconstruction from phase only. The phase used is the phase of the cross spectrum of the observations filtered through their minimum phase equivalent filters. We provide an analytical study of the propagation of noise effects in the phase estimate. Comparisons with existing methods indicate that the proposed approach is robust to noise and, at low signal-to-noise ratio (SNR), leads to significantly smaller channel estimation errors. Besides robustness to noise, the proposed method does not require knowledge of channel lengths, which are determined via an iterative procedure 相似文献
19.
原位误差情况下DOA和极化参数盲估计 总被引:1,自引:0,他引:1
现有基于电磁矢量传感器的波达方向(DOA)和极化参数联合估计算法中,均假设电磁矢量传感器的三个电偶极子和三个磁偶极子严格指向参考坐标系,即不存在原位误差.当电磁矢量传感器存在未知原位误差时,其实际极化-角度域导向矢量与理想情况下的极化-角度域导向矢量产生一定的偏差,导致现有算法的估计性能显著下降.基于极化-角度域导向矢量的一阶Taylor近似展开,给出一种原位误差情况下DOA和极化参数的盲估计算法和各参数估计的CRB界.仿真结果表明,在存在原位误差的情况下,该方法的估计性能明显优于传统方法. 相似文献
20.
Jae-Won Suh Yo-Sung Ho 《Broadcasting, IEEE Transactions on》2002,48(4):299-306
Compressed video bitstreams are intended for real-time transmission over communication networks. Most of the video coding standards employ the temporal and spatial prediction structure to reduce the transmitted video data. Therefore, the coded video bitstreams are highly sensitive to information loss and channel errors. Even a single bit error can lead to disastrous quality degradation in both time and space. This quality deterioration is exacerbated when no error resilient coding mechanism is employed to protect coded video data against the error prone environments. Error concealment is a data recovery technique that enables the decoder to conceal effects of transmission errors by predicting the lost or corrupted video data from the previously reconstructed error-free information. Motion vector recovery and motion compensation with the estimated motion vector is a good approach to conceal the corrupted macroblock data. In this paper, we develop various error concealment algorithms based on motion vector recovery, and compare their performances to those of conventional error concealment methods. 相似文献