A time–frequency representation can highlight non-stationarities in a signal. We propose to extract subsets from the time–frequency representation (TFR) for classification or recognition purposes. We ...developed two approaches. The first one is developed for TFRs obtained from the short time Fourier transform or the gliding minimum variance method. The extraction of compact subsets is viewed as a segmentation of the TFR, which is performed by morphological filtering and watershed segmentation. The second approach is developed when the TFR has been obtained using parametric estimators. We consider a hybrid estimator, the ARCAP method, and use a Kalman filter trajectory tracker to extract spectral lines. The proposed methods are illustrated by examples on natural signals: dolphin whistle acoustical signals, cavitation signals and seismic signals produced by snow avalanches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Joint estimation of direction-of-departure (DOD) and direction-of-arrival (DOA) in bistatic multiple-input-multiple-output (MIMO) radar is a powerful technique for target localization. However, in ...the scenario of large arrays in which the numbers of array elements and observations are on the same order of magnitude, the sample covariance matrix cannot directly replace the statistical covariance matrix. In this paper, we propose two robust DOA and DOD estimation algorithms based on improved 2D-Capon estimators for MIMO radar with large arrays. The sample covariance matrix of the array received signals is modified by diagonal loading technique, and then the eigenvalues and eigenvectors of the diagonally loaded covariance matrix are accurately estimated utilizing Stieltjes transform and random matrix theory (RMT). Finally, two improved 2D-Capon estimators are derived to obtain robust performance of DOD and DOA estimation. The simulation shows that the improved algorithms can estimate angles more accurately than the traditional 2D-Capon algorithm in large dimension regime.
The traditional capon spectra estimation is not suitable for extracting direction of arrival (DOA) under impulse noise. In the case of tracking and locating a single target with a single acoustic ...vector sensor (AVS), the extracted DOA may be incorrect at low signal-to-noise ratio (SNR), especially when there is an interference source near the target. In order to track and locate the target accurately even when the measurement is disturbed by abnormal values, an improved capon spectra estimator is proposed by combining cubature information filtering (CIF) and gating technology. Finally, the effectiveness of proposed method is verified by simulation experiments.
A wideband synthetic aperture radar system based on beamspace Capon beamforming is presented for urban sensing applications. Various effects of signal propagation through building materials are ...incorporated into the beamformer design. Proof of concept is provided using real data collected in a laboratory environment. Comparison between data-independent and scene-dependent beamformers is provided. The results show that the beamspace Capon beamformer outperforms the nonadaptive delay-and-sum beamformer.
The performance of the Standard Capon Beamforming (SCB) will become worse than Conventional Beamformer (CBF) in the case of small-sample errors, the steering vector errors and so on. Recently, many ...robust approaches to overcome the above problems are studied, such as Linearly Constrained Minimum Variance (LCMV), Diagonal Loading (DL) and so on. Among them, Norm Constraint Capon Beamforming (NCCB) is most popular and has a clear physical meaning. In this paper, we transform the original formulation of NCCB into Second Order Cone Programming (SOCP) form, and give a complete performance analysis of NCCB approach. Simulation results show that NCCB is more robust against the steering vector errors, and has a better power estimation of the Signal of Interest (SOI) and output Signal Interference Noise Ratio (SINR).
An exact joint probability density function (PDF) (not approximate as in) is provided for the Capon power spectral estimate and the average output power of any other deterministic filter when based ...on the same data sample covariance matrix. The cross coherence/cosine (correlation coefficient) between the two filter weights determines the extent of statistical dependence. An exact PDF for a sample covariance based (SCB) estimate of this cross coherence is derived allowing complete point-level statistical characterization of the 2-D Capon-Bartlett cross spectrum introduced in. The exact bias and variance are computed for the cross spectrum showing asymptotic consistency and inviting a natural recursive refinement for reducing bias.
In this study we consider coherent processing for time reversal microwave imaging for breast cancer detection. We derive coherent time reversal standard Capon beamformer (C-TR-SCB) and coherent time ...reversal robust Capon beamformer (C-TR-RCB) and compare their imaging performances for breast cancer detection in anatomically realistic heterogeneous 3-D breast phantoms.
In this paper, an improved Capon estimator is introduced, and reserves the characteristics of signal space after filtering the noise. More precise power estimation for both noise and signal from ...different directions can be obtained. Then, the covariance matrices of both interference-plus-noise and signal are reconstructed. With the estimated noise power and the covariance matrices, we propose 4 similar algorithms. Different from the previous methods, the proposed algorithms avoid the robust conditions in the constraints, even to solve a new convex optimization problem which would increase the amount of computation significantly. Simulation results show that the improved Capon estimator achieves better spatial resolution than existing methods, and the performance of the proposed robust adaptive beamforming is almost close to the optimal value across a wide range of signal to interference and noise ratio.
Frequency modulated continuous wave (FMCW) radar-based ranging systems provide the ability to achieve high precision in ranging targets. The FMCW radar estimates the range of the target by sending a ...frequency modulated signal and estimating the frequency of the signal returned from the target. Ranging multiple targets in FMCW radar is equivalent to estimating the frequencies of multiple sinusoids buried in noise. In this article, an algorithm based on chirp z-transform (CZT) is presented for high precision ranging in multi-target scenarios with FMCW radar. The accuracy and the efficiency of the proposed estimation algorithm is evaluated theoretically and through simulations.
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