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In this letter, we addressed the problem of estimating the time delay and the frequencies of noisy sinusoidal signals received at two spatially separated sensors. We employ the Propagator Method (PM) in conjunction with the well-known MUSIC/ root-MUSIC algorithm; the proposed method would generate estimates of the unknown parameters. Such estimates are based on the observation and/or covariance matrices. Moreover, the PM does not require the eigenvalue decomposition (EVD) or singular value decomposition (SVD) of the cross-spectral matrix (CSM) of received signals; therefore, a significant improvement in computational load is achieved. Computer simulations are also included demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: This paper considers a new azimuth-elevation direction finding algorithm for multiple acoustic plane wave signals using acoustic vector array. Firstly, a planar-plus-an-isolated sensor array geometry [P. Li, J. Sun, B. Yu, Two-dimensional spatial spectrum estimation of coherent signals without spatial smoothing and eigendecomposition, IEE Proc.-Radar Sonar Navigat. 143(5) (October 1996) 295–299] is exploited and a cross-covariance matrix is defined. Then the propagator method is used to estimate the steering vectors of acoustic vector sensors. Finally, a closed-form, automatically paired azimuth-elevation angle estimates are derived. The presented algorithm shows high azimuth-elevation estimation accuracy due to array aperture extension. In addition, the new algorithm does not need the eigen-decomposition and 2D iterative searching, and is applicable to coherent (fully correlated) signals and spatially correlated noises. Therefore, the algorithm shows low computational complexity and robustness. Monte-Carlo simulations are presented to verify the effectiveness of the proposed algorithm. [Copyright &y& Elsevier]

An acoustic vector sensor (AVS) can capture more information than a conventional acoustic pressure sensor (APS). As a result, more output channels are required when multiple AVS are formed into arrays, making processing the data stream computationally intense. This paper proposes a new algorithm based on the propagator method for wideband coherent sources that eliminates eigen-decomposition in order to reduce the computational burden. Data from simulations and lake trials showed that the new algorithm is valid: it resolves coherent sources, breaks left/right ambiguity, and allows inter element spacing to exceed a half-wavelength. [ABSTRACT FROM AUTHOR]

In this paper, we have developed a novel azimuth-estimation technique for 76-GHz adaptive-cruise-control radar systems. To resolve the rank deficiency of the signal covariance matrix and to decrease the influence of dominant noise components, we used an improved SS technique. To balance computational cost with azimuth resolution for in-vehicle implementation, we introduced a projection matrix kernel, which formally is similar to that of beamforming (BF) and semantically similar to that of the propagator method. Our technique is called the PRopagator method based on an Improved Spatial-smoothing Matrix (PRISM). Incorrectly estimating the number of targets causes the conventional BF, subspace-based (SB), or maximum-likelihood methods to produce many false spectrum peaks on the relative azimuth-to-distance plane. We omitted the process of estimating the number of targets, which requires high computational power, because our projection matrix kernel strongly suppresses these false peaks. We conducted numerical experiments using an electronic-scan radar system to examine the performance of PRISM. Compared to conventional SB methods, PRISM requires SNRs that are 2–3 dB higher but has competitive azimuth resolution at a centesimal fraction of the computational cost. [ABSTRACT FROM PUBLISHER]

A new method is presented for reducing the computational load and removing mismatch between the azimuth and elevation angle existing in estimation of subspace rotational in variance technology(ESPRIT) algorithm. Instead of eigen-decomposition, the propagator method is applied to generate rotational invariance matrix, and the elevation angle estimation is derived from the estimated azimuth angle. Thus, the computational load can be decreased greatly, and parameters paired automatically. In addition, a novel three-dimensional array is designed to accurately estimate the source signal from any direction. Simulation results showed that the proposed method is characterized by fast computation speed and high precision. [ABSTRACT FROM AUTHOR]

Abstract: Recently, Wu et al. proposed a scheme for two-dimensional direction of arrival angle estimation for azimuth and elevation angles, using the propagator method. An advantage of this method over the classical subspace based algorithms, such as ESPRIT and MUSIC, is that it does not apply any eigenvalue decomposition (EVD) to the cross spectral matrix or singular value decomposition (SVD) to the received data. This significantly reduces the computational complexity, compared to the EVD and SVD. However, Wu''s method has some drawbacks, such as pair matching between the azimuth and elevation angle estimations for multiple different sources. Furthermore, Wu''s method has an estimation failure problem in the range of practical mobile elevation angles. The objectives of this paper are two-fold: (1) to overcome these two problems with less arithmetic operation counts than Wu used; and (2) to improve the performance significantly. To achieve these objectives, we propose an antenna array configuration which avoids these problems. Simulation results verify that the proposed scheme can remove these problems and give much better performance. [Copyright &y& Elsevier]

Abstract: Accurate simulation of plasmas often requires a solution of the kinetic equation, either directly by solving the Boltzmann equation (BE) or indirectly by means of ‘particle’ simulations. However, kinetic simulations are still too computationally intensive for many large scale 3D simulations. In this paper we examine the matching between a kinetic simulation and fluid models which we use in conjunction to form a ‘hybrid’ plasma model of the breakdown process. The kinetic model is tested for convergence with respect to mesh size Δx and time-step Δt. We then implement fluid models in an attempt to reproduce the results of the kinetic model. To do this it is necessary to have a fluid model which provides accurate simulations with a wide range of Δx and Δt. We accomplish this by means of a propagator (or Green’s function) approach. The propagator method reduces to a finite difference scheme at small Δx,Δt and gives correct results across a wide range of parameters. For intermediate Δx,Δt it is necessary to take considerable care to derive the correct propagator. We apply the propagator method to two fluid models; one uses parameters which are functions of the electric field, and the other one uses parameters which are functions of the mean kinetic energy (this version also explicitly conserves energy locally). The details of the fluid models employed make a profound difference to the prediction of the breakdown. [Copyright &y& Elsevier]

A computationally efficient method for two-dimensional direction-of-arrival estimation of multiple narrowband sources impinging on the far field of a planar array is presented. The key idea is to apply the propagator method which only requires linear operations but does not involve any eigendecomposition or singular value decomposition as in common subspace techniques such as MUSIC and ESPRIT. Comparing with a fast ESPRIT-based algorithm, it has a lower computational complexity particularly when the ratio of array size to the number of sources is large, at the expense of negligible performance loss. Simulation results are included to demonstrate the performance of the proposed technique. [Copyright &y& Elsevier]

A new computationally efficient algorithm-based propagator method for two-dimensional (2-D) direction of- arrival (DOA) estimation is proposed, which uses two parallel uniform linear arrays. The algorithm takes advantage of the special structure of the array which enables 2-D DOA estimation without pair matching. Simulation results show that the proposed algorithm achieves very accurate estimation at a computational cost 4 dB lower than that of standard methods. [ABSTRACT FROM AUTHOR]