Minimum Redundancy Linear Array Research Articles

An OPR-Free Blade Tip Timing Method for Rotating Blade Condition Monitoring

Blade tip timing (BTT) is a noncontact blade vibration measurement method for rotating blade condition monitoring. However, it is difficult to install a once-per-revolution (OPR) probe due to the internal environment limitation of an engine. To solve this problem, an OPR-free BTT method is proposed in this article. Compared with the existing OPR-free methods that are based on blade displacement, this method is based on blade spacing change (BSC). In addition, a probe layout selection method based on minimum redundancy linear array (MRLA) is introduced to reduce the redundancy of the acquired signal. Simulations are conducted to prove that the proposed probe layout selection method has a stronger signal extraction capability and better robustness. The experiment is conducted to show that BSC is an alternative way for rotating blade condition monitoring and the technical route of this article is feasible.

Gridless DOA Estimation for Minimum-Redundancy Linear Array in Nonuniform Noise

A gridless direction-of-arrival (DOA) estimation method to improve the estimation accuracy and resolution in nonuniform noise is proposed in this paper. This algorithm adopts the structure of minimum-redundancy linear array (MRA) and can be composed of two stages. In the first stage, by minimizing the rank of the covariance matrix of the true signal, the covariance matrix that filters out nonuniform noise is obtained, and then a gridless residual energy constraint scheme is designed to reconstruct the signal covariance matrix of the Hermitian Toeplitz structure. Finally, the unknown DOAs can be determined from the recovered covariance matrix, and the number of sources can be acquired as a byproduct. The proposed algorithm can be regarded as a gridless version method based on sparsity. Simulation results indicate that the proposed method has higher estimation accuracy and resolution compared with existing algorithms.

2D-DOA Estimation for MIMO Radar on Monostatic L-Shaped Minimum-Redundancy Linear Arrays

This paper discussed the problem of two dimensional (2D) direction of arrival (DOA) estimation for multi-input multi-output (MIMO) radar. The minimum-redundancy linear array (MLRA) is introduced into the transmitting array and receiving array, which enables the high efficiency of the radar system. By utilizing the algorithm of multiple signal classification (MUSIC), we illustrate that the proposed scheme performs better than the uniform linear arrays (ULA) configuration under the same conditions. Simulation results verify the effectiveness of our scheme.

Two-Dimensional Direction-of-Arrival Estimation for Trilinear Decomposition-Based Monostatic Cross MIMO Radar

A low complexity monostatic cross multiple-in multiple-out (MIMO) radar scheme is proposed in this paper. The minimum-redundancy linear array (MRLA) is introduced in the cross radar to improve the efficiency of the array elements. The two-dimensional direction-of-arrival (DOA) estimation problem links to the trilinear model, which automatically pairs the estimated two-dimensional angles, requiring neither eigenvalue decomposition of received signal covariance matrix nor spectral peak searching. The proposed scheme performs better than the uniform linear arrays (ULA) configuration under the same conditions, and the proposed algorithm has less computational complexity than that of multiple signal classification (MUSIC) algorithm. Simulation results show the effectiveness of our scheme.

Design of 8mm-band Aperture Synthetic Radiometer and Imaging Experiment

An aperture synthetic radiometer (ASR) based on interferometric technology is a new type of passive microwave imaging instrument, which has high spatial resolution. Restricted by devices performance and operating wavelength, however, the system design is difficult at MMW band. In this paper, an 8mm-band aperture synthetic radiometric imaging system based on minimum-redundancy linear array is described, the performance specification of the instrument is analyzed. The preliminary imaging experiment result shows that the system has good passive MMW imaging (PMMWI) performance, indicating a bright outlook for the development of this technique in the future.

A novel method to design sparse linear arrays for ultrasonic phased array

In ultrasonic phased array testing, a sparse array can increase the resolution by enlarging the aperture without adding system complexity. Designing a sparse array involves choosing the best or a better configuration from a large number of candidate arrays. We firstly designed sparse arrays by using a genetic algorithm, but found that the arrays have poor performance and poor consistency. So, a method based on the Minimum Redundancy Linear Array was then adopted. Some elements are determined by the minimum-redundancy array firstly in order to ensure spatial resolution and then a genetic algorithm is used to optimize the remaining elements. Sparse arrays designed by this method have much better performance and consistency compared to the arrays designed only by a genetic algorithm. Both simulation and experiment confirm the effectiveness.

Beamspace Root-MUSIC for minimum redundancy linear arrays

Beamspace Root-MUSIC, a computationally efficient beamspace implementation of Root-MUSIC developed recently for use in conjunction with a uniformly spaced linear array (ULA), is discussed. Computationally efficient methods for using beamspace Root-MUSIC in conjunction with a minimum redundancy linear array (MRLA) for both the narrowband and wideband cases are developed. The MRLA is attractive in that it offers enhanced detection performance and enhanced resolution capability relative to a ULA having the same number of elements. >

Numerical annealing of low-redundancy linear arrays

An algorithm is developed that estimates the optimal distribution of antenna elements in a minimum redundancy linear array. These distributions are used in thinned array interferometric imagers to synthesize effective antenna apertures much larger than the physical aperture. The optimal selection of antenna locations is extremely time consuming when large numbers of antennas are involved. This algorithm uses a numerical implementation of the annealing process to guide a random search for the optimal array configuration. Highly thinned low-redundancy arrays are computed for up to 30 array elements. These arrays are equivalent to the optimal solutions that are known for up to 11 elements. The arrays computed for 12-30 elements have the fewest redundancies reported to date.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Minimum redundancy linear arrays for a large number of antennas

A linear array that achieves maximum resolution for a given number of antennas is advantageous in earth‐rotation aperture synthesis. This type of array is called a minimum redundancy linear array; it is obtained by reducing redundant spacings present in the array. Various methods are examined to find optimum arrays for a large number of antennas. From the systematic analysis of regular patterns in these arrays, a possibility of generalizing optimum arrays is suggested. Optimum configurations could also be used for distributing stations in an aperture synthesis array.