This paper presents a novel architecture of combining the linear array of antenna elements, where each antenna element has digitally selectable true time-delays as weights. Use of time-delays for beam-formation inhere...This paper presents a novel architecture of combining the linear array of antenna elements, where each antenna element has digitally selectable true time-delays as weights. Use of time-delays for beam-formation inherently makes the phased array network a wideband system. In particular, this technique envisage a new method of sharing antenna elements, by fixed overlapped sub-array architecture, which is able to maintain permissible element spacing to avoid grating lobe in antenna pattern. Moreover, this scheme additionally offers an easier null steering capability to the subarray architecture. This method essentially eliminates the need for intensive computation of complex weight vectors attached to each antenna element.展开更多
In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are di...In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are divided by unknown intervals because of dynamic moving.Three parameters are taken to indicate the steering vector,namely,the direction of arrivals(DOAs)of target users,the intervals of UAVs,and the orientation angles of UAVs.The orientation angles are first estimated with an auxiliary user and the DOAs are obtained through a search free rooting method,despite the intervals among the UAVs.Afterwards,the intervals among UAVs can also be calculated via exhaustive when the number of target users are no less than three.We further develop a low-complex method to reduce the computational complexity during subarray-interval estimation.The deterministic Cramér-Rao bound(CRB)of the DOA,orientation angle and subarray-interval can be inferred in a closed form.Eventually,numerical instances are cited to verify the research results.展开更多
Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit...Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit element increases.A subarray-based space-time coding(sub-STC)radar is explored to alleviate the range resolution reduction.For the proposed radar configuration,an identical waveform is transmitted and it introduces a small time offset in different subarrays.The multidimensional ambiguity function of sub-STC radar is defined by considering resolutions in multiple domains including the range,Doppler,angle and probing direction.Analyses on properties of the multi-dimensional ambiguity function of the sub-STC radar with regard to the spatial coverage,resolution performance and low sidelobes are also given.Results reveal that the range resolution and low sidelobes performance are improved with the proposed approach.展开更多
Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wr...Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wrong detection method. In this paper a modified multiple subarrays amplitude-phase united detection method is proposed , which uses both the amplitude and phase of echo from bottom.This new method not only realizes the super-wide swath coverage, but also improves the detection performance by using the phase differences among subarrays in place of phases of subarrays to estimate the phase slope image. Experimental results are also analyzed and discussed to demonstrate the effectivity of the proposed approach.展开更多
Forming nulls in the radiation pattern of an antenna is to suppress the interference from certain directions or to cancel desired signals. This letter presents an effective method based on the Gram-Schmidt orthogonal ...Forming nulls in the radiation pattern of an antenna is to suppress the interference from certain directions or to cancel desired signals. This letter presents an effective method based on the Gram-Schmidt orthogonal algorithm for fonning nulls in the subarray of a large array. The theory and realizing methods are discussed, and the corresponding fonnulas are derived in details. The simulation results are given to demonstrate the feasibility, the availability and the quick-convergence of the presented method.展开更多
In some satellite communications, we need to perform Direction Of Arrival (DOA) angle estima- tion under the restriction that the number of receivers is less than that of the array elements in an array antenna. To sol...In some satellite communications, we need to perform Direction Of Arrival (DOA) angle estima- tion under the restriction that the number of receivers is less than that of the array elements in an array antenna. To solve the conundrum, a method named subarray-synthesis-based Two-Dimensional DOA (2D DOA) angle estimation is proposed. In the method, firstly, the array antenna is divided into a series of subarray antennas based on the total number of receivers; secondly, the subarray antennas’ output covariance matrices are esti- mated; thirdly, an equivalent covariance matrix is synthesized based on the subarray output covariance matri- ces; then 2D DOA estimation is performed. Monte Carlo simulations showed that the estimation method is ef- fective.展开更多
频控阵(Frequency Diversity Array,FDA)雷达于2006年由Antonik和Wicks提出.由于FDA雷达每个相邻的天线之间存在一个频率偏移,因此在发射阵列存在距离角度二维依赖性.而对于双基地频控阵多输入多输出(FDA-Multiple Input Multiple Outpu...频控阵(Frequency Diversity Array,FDA)雷达于2006年由Antonik和Wicks提出.由于FDA雷达每个相邻的天线之间存在一个频率偏移,因此在发射阵列存在距离角度二维依赖性.而对于双基地频控阵多输入多输出(FDA-Multiple Input Multiple Output,FDA-MIMO)雷达而言,在导向矢量中耦合了波离方向、到达方向、距离(Direction Of Departure-Direction Of Arrival-range,DOD-DOA-range)三个信息,如何对三者信息进行解耦便成为研究的重点.本文针对双基地FDA-MIMO雷达的目标参数估计问题,提出了一个张量框架下的降维多重信号分类(Reduced-Dimension MUltiple SIgnal Classification,RD-MUSIC)的参数估计算法.首先,为了将发射阵列中的DOD和距离信息进行解耦,需要对发射阵列进行子阵的划分.紧接着利用高阶奇异值分解(High-Order-Singular Value Decomposition,HOSVD)算法获得信号子空间,并构建二维空间谱函数.其次,通过拉格朗日算法对空间谱进行降维,使其仅与DOA有关,从而得到DOA估计.然后利用子阵之间的频率增量来对DOD和距离信息进行解耦,同时消除相位模糊,最终得到与DOA估计自动匹配的DOD和距离估计.所提算法利用高维数据的多维结构提高了估计精度,同时能够有效地降低运算复杂度.数值实验证明了所提算法性能的优越性.展开更多
与均匀阵列相比,稀疏阵列可以使天线阵列成本降低,减少数据处理,同时带来更大的阵列孔径提高信号解析能力,在信号处理中有着广泛的应用。但是由于其排布的不规则性,计算量较大,二维面阵合成协方差矩阵存在空洞,对角度估计的准确性造成...与均匀阵列相比,稀疏阵列可以使天线阵列成本降低,减少数据处理,同时带来更大的阵列孔径提高信号解析能力,在信号处理中有着广泛的应用。但是由于其排布的不规则性,计算量较大,二维面阵合成协方差矩阵存在空洞,对角度估计的准确性造成负面影响,增强了系统对噪声的敏感度。为了克服这些问题,本文提出了一种新的角度估计方法,采用截断核范数以降低噪声的影响,并通过ℓ_(p)范数优化提升信号的稀疏表示,利用交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)算法构造子问题恢复出完整的阵列信号。随后采用子阵划分技术和基于最小二乘的传播算子模型(Propagator Method,PM)对恢复的信号处理,精确估计信号源的方位和俯仰角。仿真结果表明,所提出的角度估计算法在角度精度和时间复杂度方面具有优越性。展开更多
文摘This paper presents a novel architecture of combining the linear array of antenna elements, where each antenna element has digitally selectable true time-delays as weights. Use of time-delays for beam-formation inherently makes the phased array network a wideband system. In particular, this technique envisage a new method of sharing antenna elements, by fixed overlapped sub-array architecture, which is able to maintain permissible element spacing to avoid grating lobe in antenna pattern. Moreover, this scheme additionally offers an easier null steering capability to the subarray architecture. This method essentially eliminates the need for intensive computation of complex weight vectors attached to each antenna element.
基金supported by National Natural Science Foundation of China(No.62101601)。
文摘In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are divided by unknown intervals because of dynamic moving.Three parameters are taken to indicate the steering vector,namely,the direction of arrivals(DOAs)of target users,the intervals of UAVs,and the orientation angles of UAVs.The orientation angles are first estimated with an auxiliary user and the DOAs are obtained through a search free rooting method,despite the intervals among the UAVs.Afterwards,the intervals among UAVs can also be calculated via exhaustive when the number of target users are no less than three.We further develop a low-complex method to reduce the computational complexity during subarray-interval estimation.The deterministic Cramér-Rao bound(CRB)of the DOA,orientation angle and subarray-interval can be inferred in a closed form.Eventually,numerical instances are cited to verify the research results.
基金supported by the National Key Research and Development Program of China(2016YFE0200400)the Key R&D Program of Shaanxi Province(2017KW-ZD-12)+1 种基金the Postdoctoral Science Foundation of Shaanxi Provincethe Nature Science Foundation of Shaanxi Province
文摘Space-time coding radar has been recently proposed and investigated.It is a radar framework which can perform transmit beamforming at the receiver.However,the range resolution decreases when the number of the transmit element increases.A subarray-based space-time coding(sub-STC)radar is explored to alleviate the range resolution reduction.For the proposed radar configuration,an identical waveform is transmitted and it introduces a small time offset in different subarrays.The multidimensional ambiguity function of sub-STC radar is defined by considering resolutions in multiple domains including the range,Doppler,angle and probing direction.Analyses on properties of the multi-dimensional ambiguity function of the sub-STC radar with regard to the spatial coverage,resolution performance and low sidelobes are also given.Results reveal that the range resolution and low sidelobes performance are improved with the proposed approach.
基金Sponsored by Foundation of Underwater Acous-tic Technology National Key Lab(No.51445030205ZS2301) Foundation of the Chinese Postdoctoral Science ( No.LRB00025).
文摘Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wrong detection method. In this paper a modified multiple subarrays amplitude-phase united detection method is proposed , which uses both the amplitude and phase of echo from bottom.This new method not only realizes the super-wide swath coverage, but also improves the detection performance by using the phase differences among subarrays in place of phases of subarrays to estimate the phase slope image. Experimental results are also analyzed and discussed to demonstrate the effectivity of the proposed approach.
文摘Forming nulls in the radiation pattern of an antenna is to suppress the interference from certain directions or to cancel desired signals. This letter presents an effective method based on the Gram-Schmidt orthogonal algorithm for fonning nulls in the subarray of a large array. The theory and realizing methods are discussed, and the corresponding fonnulas are derived in details. The simulation results are given to demonstrate the feasibility, the availability and the quick-convergence of the presented method.
基金Supported by the National Natural Science Foundation of China (No.60462002 and No.60302006).
文摘In some satellite communications, we need to perform Direction Of Arrival (DOA) angle estima- tion under the restriction that the number of receivers is less than that of the array elements in an array antenna. To solve the conundrum, a method named subarray-synthesis-based Two-Dimensional DOA (2D DOA) angle estimation is proposed. In the method, firstly, the array antenna is divided into a series of subarray antennas based on the total number of receivers; secondly, the subarray antennas’ output covariance matrices are esti- mated; thirdly, an equivalent covariance matrix is synthesized based on the subarray output covariance matri- ces; then 2D DOA estimation is performed. Monte Carlo simulations showed that the estimation method is ef- fective.
文摘频控阵(Frequency Diversity Array,FDA)雷达于2006年由Antonik和Wicks提出.由于FDA雷达每个相邻的天线之间存在一个频率偏移,因此在发射阵列存在距离角度二维依赖性.而对于双基地频控阵多输入多输出(FDA-Multiple Input Multiple Output,FDA-MIMO)雷达而言,在导向矢量中耦合了波离方向、到达方向、距离(Direction Of Departure-Direction Of Arrival-range,DOD-DOA-range)三个信息,如何对三者信息进行解耦便成为研究的重点.本文针对双基地FDA-MIMO雷达的目标参数估计问题,提出了一个张量框架下的降维多重信号分类(Reduced-Dimension MUltiple SIgnal Classification,RD-MUSIC)的参数估计算法.首先,为了将发射阵列中的DOD和距离信息进行解耦,需要对发射阵列进行子阵的划分.紧接着利用高阶奇异值分解(High-Order-Singular Value Decomposition,HOSVD)算法获得信号子空间,并构建二维空间谱函数.其次,通过拉格朗日算法对空间谱进行降维,使其仅与DOA有关,从而得到DOA估计.然后利用子阵之间的频率增量来对DOD和距离信息进行解耦,同时消除相位模糊,最终得到与DOA估计自动匹配的DOD和距离估计.所提算法利用高维数据的多维结构提高了估计精度,同时能够有效地降低运算复杂度.数值实验证明了所提算法性能的优越性.
文摘与均匀阵列相比,稀疏阵列可以使天线阵列成本降低,减少数据处理,同时带来更大的阵列孔径提高信号解析能力,在信号处理中有着广泛的应用。但是由于其排布的不规则性,计算量较大,二维面阵合成协方差矩阵存在空洞,对角度估计的准确性造成负面影响,增强了系统对噪声的敏感度。为了克服这些问题,本文提出了一种新的角度估计方法,采用截断核范数以降低噪声的影响,并通过ℓ_(p)范数优化提升信号的稀疏表示,利用交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)算法构造子问题恢复出完整的阵列信号。随后采用子阵划分技术和基于最小二乘的传播算子模型(Propagator Method,PM)对恢复的信号处理,精确估计信号源的方位和俯仰角。仿真结果表明,所提出的角度估计算法在角度精度和时间复杂度方面具有优越性。
