We have investigated the utility of field-of-view adaptation for multimodal sensing in cluttered multi-target environments. Measurement data from multiple integrated sensors are collected at a fusion center, which emp...
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ISBN:
(纸本)9781467310710
We have investigated the utility of field-of-view adaptation for multimodal sensing in cluttered multi-target environments. Measurement data from multiple integrated sensors are collected at a fusion center, which employs a soft association procedure to integrate them into the estimation procedure. A variance penalty model for the limited fields-of-view property is incorporated into the state estimation procedure. this model also forms the basis of an optimization problem that determines the best next-step sensing parameters for the changing target environment. Numerical simulations demonstrate the benefit of the proposed method for both tracking and association metrics compared to a non-adaptive tracker.
Spatial filtering is the fundamental characteristic of microphone array based signal acquisition, which plays an important role in applications such as speech enhancement and distant speech recognition. In the array p...
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ISBN:
(纸本)9781467310710
Spatial filtering is the fundamental characteristic of microphone array based signal acquisition, which plays an important role in applications such as speech enhancement and distant speech recognition. In the arrayprocessing literature, this property is formulated upon beam-pattern steering and it is characterized for narrowband signals. this paper proposes to characterize the microphone array broadband beam-pattern based on the average output of a steered beamformer for a broadband spectrum. Relying on this characterization, we derive the directivity beam-pattern of delay-and-sum and superdirective beamformers for a linear as well as a circular microphone array. We further investigate how the broadband beam-pattern is linked to speech recognition feature extraction;hence, it can be used to evaluate distant speech recognition performance. the proposed theory is demonstrated with experiments on real data recordings.
Recently, we proposed an approach inspired by Sparse Component Analysis for real-time localization of multiple sound sources using a circular microphone array. the method was based on identifying time-frequency zones ...
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ISBN:
(纸本)9781467310710
Recently, we proposed an approach inspired by Sparse Component Analysis for real-time localization of multiple sound sources using a circular microphone array. the method was based on identifying time-frequency zones where only one source is active, reducing the problem to single-source localization for these zones. A histogram of estimated Directions of Arrival (DOAs) was formed and then processed to obtain improved DOA estimates, assuming that the number of sources was known. In this paper, we extend our previous work by proposing three different methods for counting the number of sources by looking for prominent peaks in the derived histogram based on: (a) performing a peak search, (b) processing an LPC-smoothed version of the histogram, (c) employing a matching pursuit-based approach. the third approach is shown to perform very accurately in simulated reverberant conditions and additive noise, and its computational requirements are very small.
We address the problem of passive estimation of the Time-Difference of Arrival (TDOA) of an unknown, stochastic signal, at two sensors. the key question addressed here is whether additional sensors, receiving the same...
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ISBN:
(纸本)9781467310710
We address the problem of passive estimation of the Time-Difference of Arrival (TDOA) of an unknown, stochastic signal, at two sensors. the key question addressed here is whether additional sensors, receiving the same signal at various relative delays, can serve to improve the accuracy in estimating the TDOA of interest between the first two sensors (without exploiting any underlying parameterization, such as dependence on the transmitter's location). We derive the Cramer-Rao Lower Bound (CRLB) on the resulting joint estimation error in a model which possibly includes multipath reflections. We show analytically, that in a multipath-free scenario, at high to moderate signal to Noise Ratios, additional sensors do not offer any improvement in accuracy. However, we also demonstrate (numerically) that in the presence of multipath reflections (possibly received at all sensors), the additional sensors can indeed assist in estimating the TDOA of interest with improved accuracy.
We consider iterative electromagnetic imaging of metallic targets hidden behind dielectric walls using sparse regularization. As in the equivalent-source method, we assume that the targets can be approximated by a set...
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ISBN:
(纸本)9781467310710
We consider iterative electromagnetic imaging of metallic targets hidden behind dielectric walls using sparse regularization. As in the equivalent-source method, we assume that the targets can be approximated by a set of filament currents whose locations are unknown. By using the iterative procedure, we reveal additional filament currents thus enlarging the target image. In order to take into account the mutual interaction between the current sources, and yet obtain the model amenable to signalprocessing, we combine the method of moments and the ray tracing.
In this paper, we propose a method for recovering and classifying WSN data while minimizing the number of samples that need to be acquired, processed, and transmitted. the problem is formulated according to the recent...
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ISBN:
(纸本)9781467310710
In this paper, we propose a method for recovering and classifying WSN data while minimizing the number of samples that need to be acquired, processed, and transmitted. the problem is formulated according to the recently proposed framework of Matrix Completion (MC), which asserts that a low rank matrix can be recovered from a small number of randomly sampled entries. the application of MC in WSN data is motivated by the assumption that sensory data exhibit intra-sensor correlations and that these data can be represented using known examples. We formulate the problem as that of recovering the low rank measurement matrix by encoding the contributions of known examples, the dictionary elements, for reconstructing and classifying the data. Experimental results using artificial data suggest that the proposed scheme is able to accurately reconstruct and classify the sensory data from a small number of measurements.
We propose a filtering method, called hierarchical particle filtering, for multi-modal sensor networks in which the unknown state vector is observed, through the measurements, in a hierarchical fashion. We partition t...
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ISBN:
(纸本)9781467310710
We propose a filtering method, called hierarchical particle filtering, for multi-modal sensor networks in which the unknown state vector is observed, through the measurements, in a hierarchical fashion. We partition the state space and the measurement space into lower dimensional subspaces. At each stage, we find an estimate of one partition using the measurements from the corresponding partition, and the information from the previous stages. We use hierarchical particle filtering for joint initiation, termination and tracking of multiple targets using multi-modal measurements. Numerical simulations demonstrate that the proposed filtering method accurately identifies the number and the categories of targets, and produces a lower mean-squared error (MSE) compared to the MSE obtained using a standard particle filter.
In this paper we analyze a two-step detection scheme for use in distributed sensor systems (e. g. statistical MIMO radar). the scheme arises when a data rate restriction forces each of the distributed systems to censo...
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ISBN:
(纸本)9781467310710
In this paper we analyze a two-step detection scheme for use in distributed sensor systems (e. g. statistical MIMO radar). the scheme arises when a data rate restriction forces each of the distributed systems to censor their detection statistics before sharing. We present the Neyman-Pearson (NP) two-step detection rule for a non-fluctuating target model (Swerling 0), which is non-linear and requires a priori knowledge of the target SNR. We then analyze the performance of a practical two-step detection rule under the non-fluctuating target model.
In detection theory, the optimal Neyman-Pearson rule applies when the characteristics of the signal and the noise are completely known. However, in many practical scenarios such as multipath or moving targets, only pa...
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ISBN:
(纸本)9781467310710
In detection theory, the optimal Neyman-Pearson rule applies when the characteristics of the signal and the noise are completely known. However, in many practical scenarios such as multipath or moving targets, only partial knowledge of the signal can be obtained. In this paper, we examine the case when the alternative hypothesis has multiple candidate models, and apply the multimodal sensor integration technique based on the exponentially embedded family to detection. It is shown that our method is asymptotically optimal as it converges to the true underlying model. Furthermore, this method is computationally efficient. We also compare the proposed method with existing classifier combining rules by simulations.
We present a novel sensing paradigm of measuring human gait. the goal of the research is to achieve low-cost gait biometrics systems with minimum data throughput for various sensing modalities. the binary measurements...
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ISBN:
(纸本)9781467310710
We present a novel sensing paradigm of measuring human gait. the goal of the research is to achieve low-cost gait biometrics systems with minimum data throughput for various sensing modalities. the binary measurements of the system are achieved by using both (1) periodic and (2) pseudo-random sampling structures. As a result, either static or dynamic gait features can be estimated from a one-bit data stream. the simulation results demonstrate the gait information acquisition capability of the proposed binary sensing technology.
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