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 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.
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 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.
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.
Standard high resolution arrayprocessing techniques are based on simultaneous sampling of the whole multiple sensorarray and, hence, require that the number of receivers should be equal to the number of receiving an...
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ISBN:
(纸本)0780375513
Standard high resolution arrayprocessing techniques are based on simultaneous sampling of the whole multiple sensorarray and, hence, require that the number of receivers should be equal to the number of receiving antennas. A switch antenna array FMCW radar system is introduced as a promising substitute for the multiple-channel array due to its lower cost and a simpler front-end circuitry. New high-resolution signalprocessing algorithms for the system composed of a single transmitter, m receiving antennas, and a single receiving channel are based on the new nonstationary version of the Capon beamforming. Simulation demonstrates that the new algorithms yield very good performance in terms of both estimation accuracy and multiple-target resolution. These algorithms give better estimation than the MUSIC algorithm even for the case of slow moving targets.
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.
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.
It is known that the design of antenna array configuration is an important issue to the antenna array applications. In this paper, we present a method to design antenna array configurations for space-time adaptive pro...
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ISBN:
(纸本)0780375513
It is known that the design of antenna array configuration is an important issue to the antenna array applications. In this paper, we present a method to design antenna array configurations for space-time adaptive processing (STAP) applied to mobile communication systems. We first derive an upper bound of the residual error power of STAP systems under the minimum mean square error (MMSE) criterion. Then, the relationship between the bound and the space-time channel auto- and cross-correlation functions is established. According to this relationship, an objective function under perfect Monte Carlo sampling is proposed, based on which the array configuration that optimizes the performance is thus obtained. Numerical simulation results under a given statistical signa environment show the effectiveness of the proposed design method.
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.
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