基于多相码的MIMO雷达模糊函数

从MIMO雷达的特点出发,在双基地雷达模糊函数基础上,提出了MIMO雷达的模糊函数.MIMO雷达的模糊函数是各双基地雷达模糊函数的线性组合,并且双基地雷达的模糊函数是直角坐标系中目标速度和位置的函数.数值计算表明,MIMO雷达的模糊函数具有直接确定目标位置和速度的能力,并且模糊函数与参考点的选取无关,通过增加发射站和接收站的数目能够提高模糊函数的位置分辨率.     

雷达信号模糊函数仿真分析研究

模糊函数是雷达信号理论中极为重要的一个概念,本文对雷达信号中常用的脉冲调幅信号、线性调频信号和巴克码信号的模糊函数进行了计算仿真,并对其进行了分析研究。     

Radiometric slope correction of synthetic-aperture radar images

The brightness in a SAR image is affected by topographic height variations due to (1) the projection between ground and image coordinates, and (2) variations in backscattering coefficient with the local scattering geometry. This paper derives a new equation for (1), i.e. the radiometric slope correction, based on a calibration equation which is invariant under a coordinate transformation. An algorithm is described to obtain the slope correction from a SAR interferogram, which also enables retrieval of the full scattering geometry. Since the SAR image and interferogram are derived from the same data set, there is no need to match the image with the calibration data. There is also no need for phase unwrapping since the algorithm only uses the fringe frequencies. A maximum-likelihood estimator for the fringe frequency is analyzed and the algorithm is illustrated by processing ERS-1 SAR data. The example demonstrates that the spatial resolution and calibration error are adequate for most applications     

MIMO雷达系统中的Cyclic-Esprit算法

一些人工信号通常具有特殊的时间特性——循环平稳特性,此时,在MIMO雷达中运用传统的DOA估计算法得到的估计结果精度很差,甚至失效。针对这一情况,文中提出了一种适用于在MIMO雷达中运用的Cyclic-Esprit算法,从理论方面推导证明了算法在MIMO雷达中运用的合理性和有效性。仿真实验表明对于具有循环平稳特性的人工信号的DOA估计,算法取得了非常好的效果。     

ACCELERATION AMBIGUITY FUNCTION OF RADAR SIGNALS AND ITS APPLICATION

High acceleration of radar targets is analyzed using Acceleration Ambiguity Function(AAF). The acceleration resolution based on AAF is defined. The AAF and acceleration resolution of rectangle pulse signal are derivated and the conclusion that its acceleration resolution is in inverse proportion with the square of its duration is drawn. In the end, these conclusions are applied to the parameter designing and performance evaluation for a certain type of pulse Doppler radar.     

On the synthesis of radar signals using the woodward ambiguity function

Optimum radar signal synthesis is one of finding a signal (the complex envelope of the radar transmitter waveform), whose ambiguity function has a magnitude closest, in the mean square sense, to a nonnegative function G(t,f), of two variables, which function is chosen keeping in mind the given radar environment. Sussman (1962) has sought a solution to this problem in a finite-dimensional subspace of the space of square-integrable functions, defined over the time interval −∞ < t < ∞. In this paper, however, the optimum signal is sought in the class L²(−T, T) of all square-integrable functions vanishing outside a finite interval, thereby removing the finite-dimensional restriction imposed by Sussman, in his work, on the class of admissible signals.This optimization problem is shown to lead to an eigenvalue problem for a nonlinear integral operator on L²(−T, T). Next, an iteration scheme is presented whereby this nonlinear operator is approximated by a sequence of linear operators. These linear operators are recursively constructed utilizing a sequence of functions G_sn (n = 0, 1, 2, …), obtained at each stage by assigning to the G-function the phase of the ambiguity function corresponding to an eigenfunction s_n associated with the largest eigenvalue of the linear operator at the previous stage. It is shown that any cluster point of the sequence of solutions of the linear eigenvalue problems thus generated furnishes at least a suboptimal solution to the basic problem of the synthesis of radar signals.     

基于模糊函数特征优化的雷达辐射源个体识别

对雷达辐射源信号进行模糊函数建模是一种有效的特征提取途径,通过对无意调制的雷达辐射源信号的模糊函数分析,提出了基于模糊函数子空间特征优化的个体识别方法,首先抽取模糊函数的"近零"频偏切片作为辐射源信号的主要特征,继而设计了切片串联策略构建了互补的特征子集对,从而分别利用典型相关分析和鉴别典型相关分析实现了切片特征的融合...     

On the application of coherent optical processing techniques to synthetic-aperture radar

Coherent optical systems are useful for the processing of data collected by sidelooking synthetic-aperture radars. This type of radar, which is useful for generating fine-resolution terrain imagery, has the capability of providing along-track, or azimuth, resolution which is much finer than the azimuth dimension of the radiated beam itself; however, the attainment of this finer resolution requires extensive processing of the received radar signal. In this paper the form of the returning radar signals is discussed, as are the general reasons why optical processing of these signals might be attractive. The required processing can be viewed as a multichannel weighted vector summation, matched filtering operation, or cross-correlation operation; the cross-correlation viewpoint is developed, as is a corresponding optical processor implementation. The role of a conical lens in simplifying reference-function realization is discussed. Finally, a Fresnel-lens interpretation of the recorded radar signal leads to a discussion of the strong physical analogy between a coherent radar system and a coherent optical system.     

EBPSK调制脉冲数据帧串信号的平均模糊函数

基于EBPSK(Extended binary phase shift keying)调制雷达通信机可输出高精度大量程的雷达测距值.同时利用EBPSK调制脉冲数据帧串信号和冲击滤波辅助解调的特殊优势进行高频谱利用率的数字通信.研究针对EBPSK调制脉冲数据帧串信号的特点,根据cooper给出的随机信号平均模糊函数的基本定义,详细推导了该信号的平均模糊函数,并通过实验仿真了平均模糊函数图.结论表明,随机EBPSK调制脉冲数据帧串雷达信号与随机二相码脉冲雷达信号的距离模糊函数类似,即在距离轴上无模糊,而其速度模糊函数则由随机EBPSK调制数据和周期的相参脉冲串共同决定,即在速度轴上呈“梳状”模糊图,其模糊瓣取决于周期脉冲串.     

MIMO系统的约束广义预测控制

讨论了输出终端带不等式约束情形的多输入多输出系统，说明了这些约束可以通过修改输入柔化系数而使其得以满足，在柔化系数的选择范围确定过程中，为了避免矩阵求逆，采用利用已知数据辨识参数的方法来确定柔化系数，从而使得问题简化。降低了计算量且加快了收敛速度。     

基于5G的外辐射源雷达模糊函数研究

随着低空空域开放和无人机等航空技术的发展,对城市或郊区等电磁频谱紧张的区域开展低空目标探测愈发重要,采用5G信号作为机会照射源的外辐射源雷达在该领域展现出了广阔的应用前景。相比4G网络,5G波形方案的实现细节发生了本质的改变,因此基于不同外辐射源信号的模糊函数也存在较大差异,而现有文献对基于5G信号的外辐射源雷达模糊函数的相关研究仍然较为缺乏。本文从信号的基本结构入手,采用对比分析的方法,从理论上对5G信号和4G信号在帧结构及物理资源结构等方面存在的差异进行了详细对比;搭建了系统仿真模型,并对基于5G信号的外辐射源雷达的模糊函数进行了仿真实验;最后,针对模糊函数中的各类副峰,分析了该模糊副峰产生的原因以及可能对信号探测性能造成的影响,并对部分副峰的抑制方式进行简单阐述。该文为基于5G信号的外辐射源雷达副峰的抑制提供了新的思路和方向。     

On the approximation of MIMO capacity

Information theoretical optimization problems related to the resource allocation of wireless cellular and ad hoc networks are not solvable in closed form due to the nonlinear logarithmic representation of the Shannon capacity. This paper introduces functional approximations to the MIMO capacity over flat Rayleigh fading channels, which allow for analytical solutions to network resource optimization problems. The precision of the suggested approximations is assessed and is shown to provide a very close match to the exact capacity expression.     

Timing synchronization using cross ambiguity function for MIMO OFDM systems with distributed antennas

In this letter, we propose a novel timing offset estimation method for multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems with distributed antennas using cross ambiguity function (CAF). The proposed algorithm has an impulse-shaped timing metric which allowed it to reduce the uncertainty due to the timing metric plateau. Simulation results show that the mean square error (MSE) performance of the proposed method is significantly improved.     

MIMO体制雷达原理及关键技术分析

在对MIMO雷达的基本原理进行概述的基础上,重点分析了MIMO雷达设计时所涉及的主要关键技术,对关键技术实现的途径及常用方法进行了讨论和分析,最后提出了还需进一步研究的方向和主要内容。     

Principles of high-resolution radar based on nonsinusoidal waves.II. Generalized ambiguity function

For pt.I see ibid., vol.31, no.4, p.359-68 (1989). A generalized ambiguity function for nonsinusoidal coded waveforms that are represented as a train of properly weighted Gaussian pulses is derived and analyzed to study its properties. Computer plots of generalized ambiguity functions of different binary codes, e.g. Barker, complementary, and pseudorandom codes, are presented. The various computer plots show that the desired thumbtack ambiguity function is achievable by nonsinusoidal coded waveforms