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Direction Finding Using Higher Order Statistics Without Redundancy

IEEE SIGNAL PROCESSING LETTERS 2013年第5期20卷 495-498页

作者： Wang, Feng Cui, Xiaowei Lu, Mingquan Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

In the last decade, 2q-MUSIC, an extension of MUSIC algorithm to an arbitrary even order 2q, has been proposed to process direction-finding problems. Despite of its better performance compared with MUSIC, it suffers from the high computational complexity, thus limiting its practical application. This letter proposes a method called Non-Redundant-2q-MUSIC using 2qth order statistics for uniform linear arrays and uniform rectangular arrays. The proposed method lowers the computational complexity effectively by removing the redundancy of the virtual array and the 2qth-order cumulant matrix. And root-MUSIC can be applied to avoid calculating the pseudo-spectrum. It is illustrated in both theoretical proof and computer simulations that the proposed method performs properly and effectively.

关键词： array redundancy high order direction finding 2q-MUSIC virtual array

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Joint Optimization of Sparse FDAs for Time Invariant Transmit Beampattern Synthesis

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IEEE SIGNAL PROCESSING LETTERS 2022年 29卷 110-114页

作者： Zhai, Weitong Wang, Xiangrong Greco, Maria S. Gini, Fulvio Beihang Univ Sch Elect & Informat Engn Beijing Peoples R China Univ Pisa Dept Informat Engn Pisa Italy

Beampattern synthesis of frequency diverse arrays (FDAs) has recently raised increased attention attributed to their range-dependent beampattern. The transmit beampattern of uniform FDA appears S-shaped, which implies coupling in the range-angle domain and thus causing unwanted energy leakage into the area of non-interest. In this work, we propose a joint optimization of sparse FDAs to synthesize a decoupled transmit beampattern from the perspective of spatial-frequency virtual array. Specifically, both spatial and spectral configuration of FDAs are optimized via joint antenna-frequency selection. In order to solve the resultant NP-hard combinatorial optimization problem, we propose an iterative reweighting strategy to transform the original problem into a convex optimization. Further, we proceed to synthesize a time-invariant decoupled beampattern by designing a time-varying unit frequency step. Comparative simulations are provided to manifest the superior performance of the proposed FDA in the metric of normalized peak sidelobe level (NPSLL) of transmit beampatterns.

关键词： Beampattern synthesis frequency diverse array virtual array time invariant convex relaxtion

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Interpolating Coprime arrays With Translocated and Axis Rotated Compressed Subarrays by Iterative Power Factorization for DOA Estimation

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IEEE ACCESS 2018年 6卷 16445-16453页

作者： Al Mahmud, Tarek Hasan Shabir, Kashif Zheng, Rui Ye, Zhongfu Univ Sci & Technol China Dept Elect Engn & Informat Sci Natl Engn Lab Language & Speech Signal Proc Inst Stat Signal Proc Hefei 230027 Anhui Peoples R China

In this paper, a novel array structure exploiting coprime arrays is proposed, which comprises the translocation of one subarray and axis rotation with a compression of another subarray to produce a larger number of consecutive lags. This composition is named CATARCS, which stands for coprime array with translocated and axis rotated compressed subarrays. The scheme offers consecutive co-array lags in remarkable number 4MN - 1 by using only 2M + N - 1 number of sensors attaining higher degrees of freedom than the state of the art, where M and N are coprime with congenial interelement spacings. However, a very few holes still exist in the co-array, which can be filled up through interpolation. In this paper, the iterative power factorization (IPF) algorithm has been demonstrated as a tool for incremented-rank-IPF matrix recovery which is unostentatious. No extra tuning parameter is required for this approach and several undesired issues of other techniques can be reconciled by this. The main contribution of this paper is suitable modification of array geometry arrangements to increase consecutive lags and to interpolate via IPF, which is used first time for direction of arrival (DOA) estimation in order to exhibit better performances in terms of detecting and resolving a larger number of sources by enhancing resolution. Later, DOA estimation can be achieved by performing multiple signal classification (MUSIC) algorithm. Simulation results validate its effectiveness by achieving lower cost, faster, and accurate DOA estimation even in lower angular separation of sources compared with other techniques like spatial smoothing MUSIC, co-array the least absolute shrinkage and selection operator, spline, iterative co-array array interpolation, and Toeplitz completion.

关键词： array interpolation coprime array consecutive lags degrees of freedom iterative power factorization mutual coupling virtual array

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Design And Analysis of the Sparse array for DoA Estimation of Noncircular Signals

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2019年第2期67卷 460-473页

作者： Gupta, Payal Agrawal, Monika Indian Inst Technol Delhi Ctr Appl Res Elect New Delhi 110016 India

Recently, many sparse arrays have been proposed to increase the number of degrees of freedom for direction of arrival (DoA) estimation especially for circular signals. Thoughmany practical signals are noncircular, still the properties of noncircularity are hardly exploited in the design of sparse linear arrays. A new array geometry for noncircular signals, which significantly increases the aperture of the virtual array, has been proposed in this paper. The structure is obtained by systematically placing the two uniform linear array (ULA) side by side. The proposed design provides the largest aperture virtual ULA (VULA) as compared to the existing array structures. The aperture of VULA and corresponding weight function are evaluated analytically. The closed-form expression of the Cramer-Rao bound, the minimum lower bound on the error in the DoA estimation, is also obtained for the proposed structure. The performance of the proposed array is studied by the exhaustive computer simulations.

关键词： DoA estimation noncircular signals nonuniform linear array virtual array Cramer Rao bound weight function underdetermined system

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PERFORMANCE ANALYSIS OF BEAMFORMING FOR MIMO RADAR

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PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER 2008年 84卷 123-134页

作者： Qu, Y. Liao, G. S. Zhu, S. Q. Liu, X. Y. Jiang, H. Xidian Univ Natl Key Lab Radar Signal Proc Xian 710071 Peoples R China Engn Inst Armed Police Dept Commun Xian 710086 Peoples R China

The full MIMO radar and the partial MIMO one are introduced. The performance analysis of beamforming for MIMO (Multiple-input Multiple-output) radar and comparisons with the phased-array radar are given. The expressions of beamwidth, gain loss and detection range for MIMO radar are derived. Theoretical analysis and simulations show that the beam of the full MIMO utilizing all virtual array elements is identical to the two-way beam of the phased-array radar, and that the beam of the partial MIMO selecting elements with different phase centers (phase shifts) is narrower, but has a gain loss. Additionally, the partial MIMO can avoid aliasing in space when the transmitting antennas are spaced at greater than half-wavelength spacing. As scanning radar, the partial MIMO radar has smaller detection range than the phased-array radar, and the full MIMO radar has the same range as the phased-array radar.

关键词： .aliasing radars beamwidth BEAMFORMING Radar Signal narrower virtual array transmitting antennas gain loss detection range phase centers full MIMO partial MIMO radar

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Ground-Based array for Tomographic Imaging of the Tropical Forest in P-Band

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2013年第8期51卷 4460-4472页

作者： Ho Tong Minh Dinh Tebaldini, Stefano Rocca, Fabio Koleck, Thierry Borderies, Pierre Albinet, Clement Villard, Ludovic Hamadi, Alia Thuy Le Toan Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy CESBIO F-31400 Toulouse France Ctr Natl Etud Spatiales F-31400 Toulouse France Off Natl Etud & Rech Aerosp F-31400 Toulouse France

In this paper we discuss the design concepts and preliminary results relating to the European Space Agency's ground-based campaign TropiScat, whose main goal is to evaluate temporal coherence at P-band in a tropical forest in quad-polarization, considering temporal lags ranging from hours to months and at different heights within the vegetation layer. The experiment has been successfully set up and operated since October 2011 at the Paracou field station, French Guiana, where the equipment was installed on top of the 55-m high Guyaflux Tower to illuminate the forest below. The system consists of a vector network analyzer connected to 20 antennas through a switchbox, which allows the use of any of them either as a transmitter or as a receiver. Vertical imaging and fully polarimetric capabilities are achieved by operating the 20 antennas in a multistatic fashion, resulting in an equivalent monostatic array consisting of 15 phase centers displaced along the vertical direction in each polarization. Such a design allows unambiguous imaging of the vegetation while yielding a minimum distance between nearby antennas on the order of 0.8 m, so as to minimize coupling effects. The equipment allows the gathering of signals with the tomographic array within a few minutes, resulting in the possibility to produce a tomographic image of the forest with a temporal sampling of 15 min. System calibration and validation was performed by employing a 2-m trihedral reflector and a rotating dihedral reflector. This allowed the evaluation of the system pulse response in all polarizations and also assessment of the extent of tower motions. As a result, tomographic images have been generated from 500 (P-band) to 900 MHz in all polarizations. Results from real data acquired in Fall 2011 confirm the feasibility of carrying out reliable coherence measurements for the whole duration of the campaign.

关键词： array design BIOMASS mission forest vertical structure ground based radar multistatic processing P-band forest tomography TropiScat tomography mode virtual array

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Design of Nonredundant Sparse Planar arrays With Reduced Mutual Coupling

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2024年第2期60卷 1272-1283页

作者： Yan, Hangqi Wang, Yuexian Wang, Ling Li, Rongfeng Liu, Wei Northwestern Polytech Univ Sch Elect & Informat Xian 710072 Peoples R China Hangzhou Appl Acoust Res Inst Hangzhou 310023 Peoples R China Queen Mary Univ London Sch Elect Engn & Comp Sci London E1 4NS England

Most existing sparse planar arrays cannot fully realize their potential in terms of the degrees-of-freedom (DOFs) due to redundancies in their co-array generation. Meanwhile, the small interelement spacing in conventional planar arrays may cause serious mutual coupling effects. In this article, a series of designs for nonredundant sparse planar arrays in different application scenarios are proposed. They can obtain the maximum possible DOFs under the constraints of area and the number of array elements. We first present the rule for nonredundancy design for planar arrays, which is the basic criterion for the following optimization problems. According to generalized disjunctive programming, we establish systematic solutions for array designs by two mixed-integer linear programming optimization approaches. Then, three classes of nonredundant planar arrays are designed to achieve minimum area, predetermined area, and reduced mutual coupling, respectively. In particular, the nonredundant planar arrays with reduced mutual coupling can be designed to both avoid small interelement spacing and obtain the minimum area, which makes them more robust to mutual coupling conditions. Simulation results are provided to demonstrate the superiority of the proposed planar array configurations for direction-of-arrival estimation.

关键词： Planar arrays Mutual coupling Estimation Transmission line matrix methods Sensors Programming Economic indicators Direction-of-arrival (DOA) estimation mixed-integer linear programming (MILP) nonredundant array planar array virtual array

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Atomic Norm-Based DOA Estimation with Sum and Difference Co-arrays in Coexistence of Circular and Non-circular Signals

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CIRCUITS SYSTEMS AND SIGNAL PROCESSING 2021年第10期40卷 5033-5053页

作者： Teng, Liping Wang, Qing Chen, Hua Liu, Wei Zhu, Wei-Ping Cai, Jingjing Tianjin Univ Schcol Elect & Informat Engn Tianjin 300072 Peoples R China Ningbo Univ Fac Informat Sci & Engn Ningbo 315211 Peoples R China Univ Sheffield Dept Elect & Elect Engn Sheffield S1 3JD S Yorkshire England Concordia Univ Dept Elect & Comp Engn Montreal PQ H3G 1M8 Canada Xidian Univ Dept Elect Engn Xian 710071 Peoples R China

Sparse arrays can increase the array aperture and degrees of freedom through the construction of either sum or difference co-arrays or both. In order to exploit the advantages of sparse arrays while estimating directions of arrival (DOAs) of a mixture of circular and non-circular signals, in this paper, a gridless DOA estimation method is proposed by employing a recently introduced enhanced nested array, whose virtual arrays have no holes. The virtual signals derived from both sum and difference co-arrays are constructed based on atomic norm minimization. It is shown that the proposed method also works when the circular and non-circular signals come from the same set of directions. Simulation results are provided to demonstrate the performance of the proposed method.

关键词： DOA estimation Enhanced nested array virtual array Atomic norm Non-circular signals

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Flow Field Imaging With Ultrasonic Guided Waves for Exploring Metallic Melts

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2018年第1期65卷 112-119页

作者： Kalibatas, Mantvydas Nauber, Richard Kupsch, Christian Czarske, Juergen Tech Univ Dresden Lab Measurement & Sensor Syst Tech D-01062 Dresden Germany

Ultrasonic guided waves enable flow measurements under harsh conditions, which are important, for instance, to monitor and optimize industrial solidification processes. The usage of single mode waveguides overcomes the problem of overheating the transducers, but requires a mechanical scanning for imaging. A multimode waveguide can carry the information of an image, but a scrambling of the signals occurs due to multiple reflections at the waveguide's boundaries. We propose a new approach to overcome the scrambling and enable flow imaging through a short waveguide: the time-reversal virtual array (TRVA) method. The time invariance of the wave equation in a linear medium allows the refocusing on a limited set of calibrated points, which form the virtual array. This virtual array can conceptually be treated as a phased array. In this paper, the TRVA has been characterized theoretically, numerically, and experimentally. For the first time, a planar velocity measurement of a rotating flow in liquid gallium-indium-tin is demonstrated through a borosilicate waveguide at room temperature. A comparison with reference measurements showed good agreement.

关键词： Flow imaging multimode waveguide time reversal (TR) ultrasound (US) virtual array

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Synthetic Aperture Ultrasound Imaging through Adaptive Integrated Transmitting-Receiving Beamformer

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ULTRASONIC IMAGING 2023年第3期45卷 101-118页

作者： Rostamikhanghahi, Hasti Sakhaei, Sayed Mahmoud Babol Noshirvani Univ Technol Dept Elect & Comp Engn Babol Mazandaran Iran Babol Noshirvani Univ Technol Dept Elect & Comp Engn Shariati Ave Babol *** Mazandaran Iran

Synthetic aperture (SA) technique is very attractive for ultrafast ultrasound imaging, as the entire medium can be insonified by a single emission. It also permits applying the dynamic focusing as well as adaptive beamforming both in transmission and reception, which results in an enhanced image. In this paper, we firstly show that the problem of designing the transmit and receive beamformers in SA structure can be formulated as a problem of designing a one-way beamformer on a virtual array with a lateral response equal to that of the two-way beamformer on SA. It is also demonstrated that the length of the virtual aperture is increased to the sum of the transmit aperture length and the receive one, which can result in an enhanced resolution. Moreover, a better estimation of the covariance matrix can be obtained which can be utilized for applying adaptive minimum variance (MV) beamforming method on the virtual array, and consequently the resolution and contrast properties would be enhanced. The performance of the new method is compared with other existing MV-based methods and is quantified by some metrics such as the full width at half maximum (FWHM) and generalized contrast to noise ratio (GCNR). Our validations on simulations and experimental data have shown that the new method is capable of obtaining higher GCNR values while retaining or decreasing FWHM values almost all the time. Moreover, for the same subarray length for estimating the covariance matrices, the computational burden of the new method is significantly lower than those of the existing rival methods.

关键词： adaptive beamforming resolution and contrast synthetic aperture ultrasound imaging virtual array

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