共查询到20条相似文献,搜索用时 139 毫秒
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天线阵列阵元通道幅相不平衡对自适应天线的性能有很大的影响。论文改进了基于注入信号的自适应天线阵元通道不平衡校正方法^[1],并对校正中的实际问题和校正性能进行了分析。该方法采用自适应滤波器校正通道,把校正和实际通信分开。仿真结果表明,该方法能够有效校正自适应阵各通道不平衡。 相似文献
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天线阵元的位置误差会影响天线阵元所接收到信号的相位。基于特征值分解的高分辨率波达方向(DOA)估计算法对信号的相位误差非常敏感。针对多输入多输出(MIMO)阵列,本文基于遗传算法,利用自校正思想,构造一个对不同方向空间谱值进行加权求和的自适应权函数,结合MUSIC方法,构建个体适应度函数,实现了MIMO阵列阵元位置误差与DOA的联合在线估计。仿真结果表明该方法进行DOA估计的同时,还可以完成阵列位置误差的在线估计与校正,提高了系统参数估计的鲁棒性。 相似文献
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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
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探讨了在一台高频表面波雷达样朵上的接收天线阵的交准方法。这是一个均匀的、线性的天线阵,由十个单级子组成,架设在面向大西洋的一处峭壁上。该校准方法利用矩阵补偿各阵元不同的增益与相位响应、阵元间的互耦、不完善的地网和峭壁上的信号衍射。在给出的结果中可以看出该方法(a),减少阵元增益和相位校正误差;(b)减少单和双目标方向估值(由高分辨率侧向法获得)误差;(c)当双目标角度分隔降为零时,提高了高分辨率测 相似文献
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窄波束全向接收的自适应天线阵研究 总被引:4,自引:0,他引:4
为了实现对短波频段全空域低信噪比信号的良好接收,本文提出了一种窄波束全向接收的知适应天线阵。文中首先简要回顾了自适应天线阵的基本理论,并针地短波波段频程较宽的特点,提出了一种接收信号频率决定阵元间距的阵元间距动态可变组阵方案,文末通过计算机仿真比较了该方案实现的窄波束全向接收自适应天线阵和常规短波天线阵的性能。 相似文献
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改进的GPS抗干扰自适应天线阵性能研究 总被引:2,自引:1,他引:1
文章提出了一种用于GPS接收机的新型抗干扰自适应天线阵,并给出了对其方向图和输出信干噪比的仿真过程.比较了在相同的信号环境时,该天线阵与常用的均匀直线阵、等间隔圆形阵的性能.结果表明,使用该自适应阵可以改善天线阵的方向图,提高输出信号干扰噪声比SINR,增强接收机的抗干扰能力. 相似文献
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F. Silva-Rivas C.-Y. Lu P. Kode B. K. Thandri J. Silva-Martinez 《Analog Integrated Circuits and Signal Processing》2009,59(1):91-95
In this paper, a calibration technique for Noise Transfer Function (NTF) optimization of Continuous-Time Bandpass Sigma Delta
(CT BP ΣΔ) modulators is presented. The proposed technique employs a test tone applied at the input of the quantizer to evaluate
the noise transfer function of the Analog-to-Digital Converter (ADC) using the capabilities of the Digital Signal Processing
(DSP) platform usually available in mixed-mode systems. Once the ADC output bit stream is captured, necessary information
to generate the control signals to tune the ADC parameters for best Signal-to-Quantization Noise Ratio (SQNR) performance
is extracted via an LMS software-based algorithm. Simulation results show that notch frequency of the NTF due to process variations
and temperature tolerances can be tuned using the proposed methodology. The proposed global calibration approach can be used
during the system start-up and the idle system time. The proposed approach uses a single in-band calibration tone, but it
can be expanded using out-of band test tones for background calibration schemes. 相似文献
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Gert van der Horn Johan H. Huijsing 《Analog Integrated Circuits and Signal Processing》1997,14(3):207-222
In many applications electronic sensors are used toimprove performance and reliability of measurement systems. Suchsensors should provide a correct transfer from the physical signalto be measured to the electrical output signal. One importantstep to achieve this, is to calibrate each sensor by applyingdifferent reference input signals and adjusting the sensor transferaccordingly. Besides expensive reference equipment the calibrationprocess takes much time and attention per individual sensor,which means a considerable increase in sensor production costs.By including at the sensor or sensor interface chip a programmablecalibration facility the calibration of such smart sensors caneasily be automated and can be executed for a batch of sensorsat a time, thus minimizing the calibration time and costs. Thispaper presents a calibration method and options for integrationin the smart sensor concept, in hardware as well as in software.An advantage of the proposed method is that it does not needa large matrix of calibration data, which needs to be storedin a look-up table or converted into a correction formula, butinstead it uses a step-by-step approach to correct the sensortransfer at each calibration measurement until the error is sufficientlysmall. 相似文献
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It is proposed that by merging the complex signals available from both of the cross-polarized receive channels of a time-multiplexed coherent polarimetric radar, an effective doubling of the signal-to-noise ratio in the cross-polarized component can be realized with no increase in transmitter power, as compared to the more conventional method of using only one channel. A spectral analysis of the merged sequence is presented showing advantages unique to this approach with applications in reflectivity measurement and channel phase calibration 相似文献
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This work describes two algorithms designed for remote calibration of an Nc-element active phased-array antenna. These algorithms involve transmission of N⩾Nc time multiplexed orthogonal encoded signals. The received signals are coherently detected, accumulated in vector forms, and decoded with the inverse of the orthogonal encoding matrix. The unitary transform encoding (UTE) algorithm is most suited for digital beamforming as it requires additional encoding hardware for an analog implementation. The control circuit encoding (CCE) algorithm is ideally suited for analog beamformers as it requires no additional encoding hardware. The CCE method encodes phased-array elemental signals using a Hadamard matrix to control the switching of intrinsic phase shifter delay circuits. The UTE and CCE algorithms can reduce the average measurement integration times for the complete set of calibration parameters by ~Nc relative to the corresponding values for single-element calibration procedures. This is significant for satellite systems as calibration must be performed in a short enough time window that the process can be treated as being stationary. Proofs are given that the orthogonal codes satisfy the mathematical lower bounds for the asymptotic forms of calibration parameter estimation variances 相似文献
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We present the theory and application of a novel calibration system for millimeter and microwave polarimeters. The technique is a simple extension of the conventional wire-grid approach, but employs a thin dielectric sheet rather than a grid. The primary advantage of this approach is to obtain a calibration signal that is only slightly polarized, which can be beneficial for certain applications such as astronomical radiometers that measure very low levels of polarization, or systems with a small dynamic range. We compare this approach with other calibration techniques and discuss its successful use in the calibration of the polarization observations of large angular regions experiment, designed to measure polarization in cosmic microwave background radiation 相似文献
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McGettrick A.J. Duffin K. Johnstone W. Stewart G. Moodie D.G. 《Lightwave Technology, Journal of》2008,26(4):432-440
The principles and implementation of a phasor decomposition method for analyzing signals in tunable diode laser spectroscopy with wavelength modulation are described. This new technique enables recovery of the isolated and normalized residual amplitude modulation (RAM) signal from measured first harmonic signals at any chosen fundamental modulation frequency. Like the previously reported RAM technique, this new approach is absolute, yielding gas absorption line shape functions, concentrations and pressures without the need for calibration, under certain defined operating conditions. It represents an advancement of the RAM technique in that it obviates the need to operate at a specific high frequency to achieve phase quadrature between the RAM and derivative signals: the signals may be recovered at their maximum levels at any frequency. Measurements of the 1650.96 nm and the 1666.2 nm rotation/vibration absorption line shape functions for 1% and 10% methane in nitrogen at various pressures are compared to theoretical predictions derived from HITRAN data. The excellent agreement confirms the validity of the new technique. Further measurements of concentration and pressure confirm the efficacy of the technique for determining concentration in industrial process environments where the pressure may be unknown and changing. With the above features this new method is particularly suited to stand alone instrumentation for on-line deployment in industrial processes where the calibration factors in the conventional approach would present significant difficulties. 相似文献
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A new approach to array processing (i.e., direction-finding, signal separation and reconstruction, and calibration) is considered. The main advantages of the advocated approach is that the multidimensional search associated with maximum likelihood-based estimators or the single-dimensional search associated with MUSIC-type methods are eliminated. While the proposed method is based on the Analytical Constant Modulus Algorithm that was recently proposed by Van der Veen and Paulraj, it is not limited to constant modulus signals or any other specific type of signals. The sensor array elements are assumed to have the same, up to a multiplicative constant, angle-dependent, unknown gain pattern. We show that under this assumption it is possible to estimate the array response matrix and then use the result for direction finding, if the nominal array manifold is known, at least approximately. It is also possible to use the estimated array response matrix in order to separate and reconstruct the signals, or calibrate the array shape or response. We provide performance analysis of the algorithm and compare the results with computer simulations. We also examine the sensitivity of algorithm to the model assumptions. The method can be applied in the presence of specular multipath (using spatial smoothing) but it is not suitable for signal separation in the presence of severe diffuse multipath. 相似文献