共查询到20条相似文献,搜索用时 78 毫秒
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Direct quadrature modulation technology is suitable for wide-band radar signal generation. However, this method has rigorous requirements on amplitude and phase balance of the orthogonal input signals. If the requirements are not satisfied, there would be modulation errors such as image frequency and oscillator leakage that cannot be filtered. The modulation errors will therefore raise the noise floor of the range profile and reduce the dynamic range of the Synthetic Aperture Radar (SAR) image as a whole. In this paper, the wide-band In-phase/Quadrature-phase (I/Q) modulation errors are modeling analyzed, and the influence of wide-band I/Q modulation errors on SAR imaging is discussed. Furthermore, a compensation method of modulation errors is proposed, and the circuit implementation of the radar signal generation and pre-distortion is presented. The experimental results illustrate that the curves of the I/Q amplitude and phase imbalance errors are successfully extracted and the rejection of image frequency improved significantly, thus meets the requirements of the SAR imaging. 相似文献
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在脉压体制的雷达中,正交插值和脉冲压缩是雷达信号处理的前端,通用的分开处理的方法增加了系统结构的复杂性以及成本的提高.本文通过对正交插值脉冲压缩各种工程实现方法的研究,采用合成算法,在一定条件下简化系统结构并不增加运算量,并通过仿真在理论上讨论其性能和可行性. 相似文献
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Baseband signal processing involves the provision of quadrature channels if phase information is of importance. A technique of producing extremely well matched quadrature phase detectors over a 40 dB dynamic range is described, together with a scheme to measure the resulting phase errors to an accuracy of less than 1 min. 相似文献
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Wenqin Wang 《Geoscience and Remote Sensing, IEEE Transactions on》2007,45(9):2695-2700
The use of a novel synchronization link to compensate time, phase, and spatial synchronization errors is proposed, aiming at the development of a practical synchronization technique for bistatic synthetic aperture radar (BiSAR) real-time imaging. With the proposed technique, an amplitude-modulated signal emitting from the transmitter is received by a passive receiver and divided into two channels. One is passed through an envelope detector and then used to trigger the sampling clock, and the second is used to achieve spatial synchronization and phase synchronization. Finally, the residual time synchronization errors are compensated with a proposed high-precision range realignment method, and the residual phase synchronization errors are compensated with autofocus algorithms. This technique allows a passive receiver, which is teamed with an illuminator at a safe standoff distance, to receive the data reflected from potentially hostile areas of interest. Thus, this configuration, making real-time imaging possible, has a particular value in military applications. Simulation results show that successful adaptive synchronization for BiSAR real-time imaging is possible by using this dedicated synchronization link. 相似文献
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An adaptive direct conversion transmitter 总被引:8,自引:0,他引:8
Hilborn D.S. Stapleton S.P. Cavers J.K. 《Vehicular Technology, IEEE Transactions on》1994,43(2):223-233
An adaptive direct conversion transmitter is presented, in which adjacent channel power measurements are used to simultaneously compensate for both power amplifier (PA) nonlinearity and quadrature modulator (QM) errors. Three main contributions are given. First, analysis is presented which shows that adjacent channel power is a quadratic function of power amplifier nonlinearity as well as quadrature modulator errors. Quadrature modulator errors are gain imbalance, phase splitter error, and DC offset errors. Second, a new optimization method is given which uses the predicted adjacent channel power surface to obtain fast convergence. Third, simulation and measured results are given for an adaptive system using offset QPSK modulation. The measured results confirm the analysis and show that a 20-dB reduction in adjacent channel power is achievable. In general, the adaptive direct conversion transmitter has applications in any system where power efficiency and spectral efficiency are important, and allows the use of smaller more efficient power amplifiers in a direct conversion architecture 相似文献
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高频地波雷达(HFSWR)使用多重信号分类算法MUSIC 算法估计信号源的到达角时,接收通道幅相特性的不一致会使MUSIC 算法的分辨性能下降,甚至完全失效。文中针对单极子/ 交叉环天线提出一种基于海洋回波的相位校正方法:首先,预选出一阶谱区的大信噪比谱点;然后,结合天线三通道相位中心一致的特性进行有效谱点的筛选;最后,利用有效谱点的相位差均值估计出相位误差。将该方法应用于北部湾海域收集的实测数据处理中,验证了方法的有效性。 相似文献
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本文介绍I/Q通道误差自动校正的实现方法。校正网络由组合逻辑组成,可以校正同相支路和正交支路的幅相误差和直流偏移。校正系数由DSP根据相参测试信号算出。当幅度误差为0.1dB,相位误差为5时,产生的相对镜像电平为-27dB。经过误差自动校正后,相对镜像电平下降到-52dB。 相似文献
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针对MIMO雷达的信号特点,采用了一种多角度的雷达侦察方法,从不同的方位获取同一部雷达的独立信号样本。并在此基础上,运用主分量分析方法估计信号波形个数,运用独立分量分析的盲源分离方法分离出MIMO雷达信号的各个正交分量,最终以正交频分线性调频信号为例,在信噪比为0 dB的情况下对该信号进行了仿真分析,其结果验证了该方法的有效性。 相似文献
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The paper presents a verification procedure developed for the quadrature processing unit of radar with stepwise frequency modulation of the probing signal. The computer simulation and experiments on verifying the developed and manufactured quadrature processing unit were performed for the cases of placing a single stationary point object at distances 9 and 24 meters. The effect of inaccuracy in setting the phase shift between the reference oscillations of quadrature mixer on the waveform of spatial reflectogram was investigated by using the developed verification procedure; and it was shown that phase shift errors could lead to the generation of false responses. 相似文献