This paper presents a technique for real time multi-channel signalprocessing of biological neural data. The major objective is the extraction of action potentials from neural data streams continuously acquired from a...
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ISBN:
(纸本)0780385454
This paper presents a technique for real time multi-channel signalprocessing of biological neural data. The major objective is the extraction of action potentials from neural data streams continuously acquired from a multi-electrode sensorarray. For the actual detection process a wavelet-based method will be proposed, which allows efficient filtering as well as the definition of a robust threshold. In order to match the real time constraints for the wavelet transform an efficient and fast algorithm (lifting scheme) was used. An exemplary 8-channel implementation will be described exploiting the parallel potentials of a Xilinx Virtex field programmable gate array (FPGA). This work is part of a project concerned with the development of a microsensorchip system for neural data analysis at the University of Rostock, Germany.
In this paper we provide a tutorial description of recent results of the research activity at the University of Pisa on multibaseline (MB) InSAR processing. The main focus is on the problem of retrieving both heights ...
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ISBN:
(纸本)0780385454
In this paper we provide a tutorial description of recent results of the research activity at the University of Pisa on multibaseline (MB) InSAR processing. The main focus is on the problem of retrieving both heights and radar reflectivities of natural layover areas by means of a cross-track InSAR (XTI-SAR) system. It is formulated as the problem of detecting and estimating a multicomponent signal corrupted by multiplicative noise and by additive white Gaussian noise. The problem of estimating the number of signal components in the presence of speckle is also addressed. Finally, e brief mention is given to recent research trends on robust methods for non-perfectly calibrated arrays and on MB-SAR tomography, which is an extension of MB-InSAR for fill 3D mapping of semitransparent volume scattering layers.
In this paper, an efficient low-complexity robust adaptive beamforming method based on worst-case performance optimization is proposed. Lagrangian method was applied to obtain the expression for the robust adaptive we...
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ISBN:
(纸本)9781424422401
In this paper, an efficient low-complexity robust adaptive beamforming method based on worst-case performance optimization is proposed. Lagrangian method was applied to obtain the expression for the robust adaptive weight vector, which is optimized on the boundary of the steering vector uncertainty region, that is to say, in the worst mismatch case. Combining the constraint condition and the eigendecomposition of the array covariance matrix, root-finding method is used to obtain the optimal Lagrange multiplier. Then, the diagonal loading-like robust weight vector is achieved. ne implementation efficiency is greatly improved since the main computational burden is the eigendecomposition operator. Numerical results show that the performance of the proposed method is nearly identical to the robust Capon beamforming.
For a set of T independent N-variate Gaussian training samples (T < N), we derive a test for discriminating between stationary autoregressive models of order m, AR(m), and time-varying autoregressive models of orde...
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ISBN:
(纸本)1424403081
For a set of T independent N-variate Gaussian training samples (T < N), we derive a test for discriminating between stationary autoregressive models of order m, AR(m), and time-varying autoregressive models of order m, TVAR(m).
One of the applications of advanced arraysignalprocessing is immersion ultrasonic non-destructive testing (NDT), where a solid test sample and an array of transducers are immersed in water, for the purpose of imagin...
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ISBN:
(纸本)9781479914814
One of the applications of advanced arraysignalprocessing is immersion ultrasonic non-destructive testing (NDT), where a solid test sample and an array of transducers are immersed in water, for the purpose of imaging the test sample. To do so, the knowledge of the shape of the upper surface of the test sample is needed. We model the interface between water and the solid as an incoherently spatially distributed reflector. We then develop a covariance fitting based approach to estimate the parameters of the shape of the upper surface of the test sample. With the knowledge of the estimated shape of this surface, we use the same approach to estimate the parameters of the shape of a crack inside the test sample. Numerical simulations are conducted to show the accuracy of the proposed approach.
Traditional directional modulation (DM) designs are based on the assumption that there is no multi-path effect between transmitters and receivers. One problem with these designs is that the resultant systems will be v...
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ISBN:
(纸本)9781538647523
Traditional directional modulation (DM) designs are based on the assumption that there is no multi-path effect between transmitters and receivers. One problem with these designs is that the resultant systems will be vulnerable to eavesdroppers which are aligned with or very close to the desired directions, as the received modulation pattern at these positions is similar to the given one. To solve the problem, a two-ray multi-path model is studied for positional modulation and the coefficients design problem for a given array geometry and a location-optimised antenna array is solved, where the multi-path effect is exploited to generate a given modulation pattern at desired positions, with scrambled values at positions around them.
We consider the problem of tracking a magnetic target as it travels in a straight-line path in the vicinity of N magnetic sensors. The target is modeled as a magnetic dipole, and we study tracking algorithms when the ...
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ISBN:
(纸本)9781424422401
We consider the problem of tracking a magnetic target as it travels in a straight-line path in the vicinity of N magnetic sensors. The target is modeled as a magnetic dipole, and we study tracking algorithms when the sensors are total-field (scalar) magnetometers and vector magnetometers. A novel, computationally-efficient vector-field algorithm is presented that jointly processes the data from N sensors, yielding estimates of the track and the target dipole moment vector. Simulation examples are included to illustrate the performance of the total-field and vector algorithms.
Increasing the number of sources to be processed from a given array of sensors is an important problem in sensorarraysignalprocessing and of interest to many researchers. This problem has also been tackled with the...
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ISBN:
(纸本)9781728119465
Increasing the number of sources to be processed from a given array of sensors is an important problem in sensorarraysignalprocessing and of interest to many researchers. This problem has also been tackled with the virtual array based approach where the covariance and cumulant lags provide a virtual sensor. Here, an important parameter which affects the parameter estimation accuracy and latency is weight function. The weight function is defined as the frequency of occurrence of each virtual sensor in the virtual array. We provide the close-form expression of virtual array corresponding to linear array. We have also analytically evaluated the weight function of virtual array and have also studied the effect of the weight function on parameter estimation. Simulation results show the parameter estimation accuracy is significantly improve with high weight function.
An adaptive algorithm for azimuth-angle estimation of moving sources in the presence of array nonidealities is proposed. The method, termed unitary element-space Capon (UES-Capon) beamformer, is robust in the face of ...
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ISBN:
(纸本)9781467310710
An adaptive algorithm for azimuth-angle estimation of moving sources in the presence of array nonidealities is proposed. The method, termed unitary element-space Capon (UES-Capon) beamformer, is robust in the face of small number of snapshots and fully takes into account effects such as mutual coupling, mounting platform reflections, and sensor's misplacement errors. Unlike most of the robust beamformers available in the literature, the proposed method is based on QR-decomposition and real-valued polynomial root tracking. Furthermore, it is applicable to sensorarrays of arbitrary configuration. Numerical results using a real-world antenna array are included, illustrating the excellent performance of the proposed method, both in terms of SINR and fast adaptivity to moving sources.
PATENT PENDING. Time-of-arrival (TOA) localization is tightly coupled with sensor time synchronization. Synchronization can be obtained by GPS, atomic clocks or message exchange protocols. All methods affect the energ...
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ISBN:
(纸本)9781467310710
PATENT PENDING. Time-of-arrival (TOA) localization is tightly coupled with sensor time synchronization. Synchronization can be obtained by GPS, atomic clocks or message exchange protocols. All methods affect the energy sources and the synchronization protocols use valuable bandwidth. We present self-synchronized localization algorithms that rely exclusively on TOA measurements performed by the sensor network on passing sources rendering it completely passive. Localization performance is close to that provided by a perfectly synchronized network. Such algorithms can also be used for sensor network synchronization and communication networks in general.
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