This paper presents a statistical analysis of two schemes for intelligent STAP training data selection in Gaussian and non-Gaussian interference backgrounds. Performance analysis of the two methods is carried out usin...
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ISBN:
(纸本)0780375513
This paper presents a statistical analysis of two schemes for intelligent STAP training data selection in Gaussian and non-Gaussian interference backgrounds. Performance analysis of the two methods is carried out using simulated as well as measured radar data.
This paper describes the use of voice activity defector (VAD) in microphone arrayprocessing for hand-free systems. Two different types of VAD are proposed using conventional and adaptive beamforming. Taking into acco...
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ISBN:
(纸本)0780375513
This paper describes the use of voice activity defector (VAD) in microphone arrayprocessing for hand-free systems. Two different types of VAD are proposed using conventional and adaptive beamforming. Taking into account the fact that the speech signal is not present at all time in human conversations, both signal of interest and noise can be better estimated. Simulation results show that the VAD significantly improves the performance of the arrayprocessing algorithms. The performances of the two types of VAD are also compared in the paper.
The sensor-Angle Distribution (SAD) is a recently introduced tool representing the power arriving at each sensor as a function of angle (or spatial frequency). It can be used to characterize near-field scatter environ...
ISBN:
(纸本)0780375513
The sensor-Angle Distribution (SAD) is a recently introduced tool representing the power arriving at each sensor as a function of angle (or spatial frequency). It can be used to characterize near-field scatter environments. The SAD, as originally introduced, undersampled the spatial correlation of the received signal (measured at each sensor) causing the SAD to be aliased for common source location cases. In this paper we indicate how this may be overcome. Additional results are provided showing that the SAD may be implemented as a multiple weighted subarray beamformer.
In this paper, the performance of a subspace beamformer, namely the multiple signal classification algorithm (MUSIC), is scrutinized in the presence of sensor position errors. Based on a perturbation model, a relation...
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ISBN:
(纸本)0780375513
In this paper, the performance of a subspace beamformer, namely the multiple signal classification algorithm (MUSIC), is scrutinized in the presence of sensor position errors. Based on a perturbation model, a relationship between the array autocorrelation matrix and the source autocorrelation matrix is established. It is shown that under certain assumptions on the source signals, the Gaussian sensor perturbation errors can be modelled as additive white Gaussian noise (AWGN) for an array where sensor positions are known perfectly. This correspondence can be used to equate position errors to an equivalent signal-to-noise ratio (SNR) for AWGN in performance evaluation. Finally, Cramer-Rao bound for the position perturbations that can be computed using the Cramer-Rao bound relations for the additive Gaussian noise case at high SNR's.
The ambiguity problem in direction-of-arrival (DOA) estimation using a sensorarray, manifests itself as spurious peaks in the DOA spectrum, making the true targets indistinguishable from the false alarms. A criterion...
ISBN:
(纸本)0780375513
The ambiguity problem in direction-of-arrival (DOA) estimation using a sensorarray, manifests itself as spurious peaks in the DOA spectrum, making the true targets indistinguishable from the false alarms. A criterion that determines the presence of certain ambiguities inherent to a symmetric linear array was proposed in the literature. The criterion is a useful tool to design reliable sensorarrays. In this paper, a generalization of this ambiguity criterion is presented. The new ambiguity criterion encompasses more ambiguous DOAs and therefore gives a more accurate measurement of the reliability of an array design.
This paper concerns the problem of array shape estimation from clutter (ASEC) for a towed active sonar array. Although heading sensors can provide towed-array shape information, they are sometimes not sufficiently ava...
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ISBN:
(纸本)0780375513
This paper concerns the problem of array shape estimation from clutter (ASEC) for a towed active sonar array. Although heading sensors can provide towed-array shape information, they are sometimes not sufficiently available or accurate to facilitate beamforming with low sidelobe levels necessary for detection of low-Doppler targets, especially in the presence of severe bottom reverberation. We propose a maximum likelihood array shape calibration technique that exploits the azimuth-Doppler frequency relationship of the clutter by fitting the reverberation snapshots from a single sonar ping to the low rank space-time clutter subspace.
In sensor networks, where power and bandwidth are at a premium, there is a clear need to use compression to limit the amount of information exchanged by the sensors. In this paper we study the signal compression probl...
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ISBN:
(纸本)0780375513
In sensor networks, where power and bandwidth are at a premium, there is a clear need to use compression to limit the amount of information exchanged by the sensors. In this paper we study the signal compression problem in situations where signals are being processed for the purpose of source localization. In these scenarios compression should be optimized for the accuracy of source localization, rather than to provide a reproduction of the signals with some desired fidelity. We show how this leads to novel design techniques that have clear advantages over standard quantizer design approaches.
Ultrasonic inspection methods are commonly used in the nondestructive evaluation of welds to detect flaws in the weld region. An important characteristic of ultrasonic inspection is the ability to identify the type of...
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ISBN:
(纸本)0780375513
Ultrasonic inspection methods are commonly used in the nondestructive evaluation of welds to detect flaws in the weld region. An important characteristic of ultrasonic inspection is the ability to identify the type of discontinuity that gives rise to a particular signal. Standard techniques rely on differences in individual A-scans to classify the signals. This paper proposes an ultrasonic signal classification technique based on the information in a group of signals. The approach is based on a 2-dimensional transform and principal component analysis, for generating a reduced dimensional feature vector for classification. Results of applying the technique to data obtained from the inspection of welds are presented.
This paper proposes a novel wideband structure for arraysignalprocessing. A new wideband model is formed where the observations are linear functions of the source amplitudes, but nonlinear in the direction of arriva...
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ISBN:
(纸本)0780375513
This paper proposes a novel wideband structure for arraysignalprocessing. A new wideband model is formed where the observations are linear functions of the source amplitudes, but nonlinear in the direction of arrival (DOA) parameters. The method lends itself well to a Bayesian approach for jointly estimating the model order and the DOAs through a reversible jump Markov chain Monte Carlo (MCMC) procedure. The source amplitudes are estimated through a maximum a posteriori (MAP) procedure. The DOA estimation performance of the proposed method is compared with the theoretical Cramer-Rao lower bound (CRLB) for this problem. Simulation results demonstrate the effectiveness and robustness of the method.
Microphone arrays provide new opportunities for noise reduction and speech enhancement. This paper presents a novel decomposition of the estimation problems for short-time spectral amplitude (STSA), log STSA, and phas...
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ISBN:
(纸本)0780375513
Microphone arrays provide new opportunities for noise reduction and speech enhancement. This paper presents a novel decomposition of the estimation problems for short-time spectral amplitude (STSA), log STSA, and phase in the Bayesian estimation framework. The decomposition is based on the notion of sufficient statistics for the microphone array case. It nicely generalizes the well-known single-channel Ephraim-Malah estimators [4, 5] to the microphone array case. We also compare noise reduction obtained in the single channel with the two- and four-channel cases on real data.
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