As with the case of instantaneous frequency, it is often difficult to interpret the instantaneous bandwidth of most signals: both quantities typically range beyond the spectral support of the signal, yielding the para...
详细信息
As with the case of instantaneous frequency, it is often difficult to interpret the instantaneous bandwidth of most signals: both quantities typically range beyond the spectral support of the signal, yielding the paradox that the instantaneous bandwidth (and frequency) can be greater than the global bandwidth of the signal. A new definition of instantaneous frequency that does not suffer from this difficulty has recently been given, and we build on those results here to obtain a new definition of instantaneous bandwidth. Kernel constraints for a Cohen-class time-frequency distribution to yield these new results for its conditional moments are also given.
CORDIC algorithms offer an attractive alternative to multiply-and-add based algorithms for the implementation of two-dimensional rotations, preserving either norm: (x2 + y2) 1/2 or (x2 - y2) 1/2 . Indeed these nor who...
详细信息
CORDIC algorithms offer an attractive alternative to multiply-and-add based algorithms for the implementation of two-dimensional rotations, preserving either norm: (x2 + y2) 1/2 or (x2 - y2) 1/2 . Indeed these nor whose computation is a significant part of the evaluation of the two-dimensional rotations, are computed much more easily by the CORDIC algorithms. However the part played by norm computations in the evaluation of rotations becomes quickly small as the dimension of the space increases. Thus, in spaces of dimension 5 or more, there is no practical alternative to multiply-and-add based algorithms. In the intermediate region, dimensions 3 and 4, extensions of the CORDIC algorithms are an interesting option. The four-dimensional extensions are particularly elegant and are the main object of this paper.
In this paper, we propose a new algorithm for computing a singular value decomposition of a matrix product. We show that our algorithm is numerically desirable in that all relevant residual elements will be numericall...
详细信息
In this paper, we propose a new algorithm for computing a singular value decomposition of a matrix product. We show that our algorithm is numerically desirable in that all relevant residual elements will be numerically small. Our algorithm can be extended to a product of a larger number of upper triangular matrices.
We present an analysis and computational results relating to the regularized restoration of subpixel information from undersampled data. The method makes use of a small set of images in various stages of defocus. An i...
详细信息
ISBN:
(纸本)0819406945
We present an analysis and computational results relating to the regularized restoration of subpixel information from undersampled data. The method makes use of a small set of images in various stages of defocus. An iterative implementation permits the incorporation of a non- negativity constraint. The problem we consider is fundamentally under-determined, but useful results can be obtained in reasonably low noise conditions.
An algorithm is proposed to compute samples of any bilinear joint time-frequency representation of the Cohen's class. The computation is performed on a decimated sampling grid, mapping N = 3BD signal samples into ...
详细信息
ISBN:
(纸本)0819416207
An algorithm is proposed to compute samples of any bilinear joint time-frequency representation of the Cohen's class. The computation is performed on a decimated sampling grid, mapping N = 3BD signal samples into N = K × L critical samples of the joint representation in the time-frequency domain. This is in contrast with the usual approaches that perform the computation on a much denser grid, mapping N signal samples into N × N samples in the time-frequency plane. The algorithm is based on the discrete Zak transform and represents an extension of the work by Auslander et al. on fast computation of the ambiguity function. For a number of popular representations, the algorithm is shown to have computational complexity about the same as an ordinary FFT.
A high performance VLSI architecture to perform combined multiply-accumulate, divide, and square root operations is proposed. The circuit is highly regular, requires only minimal control, and can be pipelined right do...
详细信息
ISBN:
(纸本)0819406945
A high performance VLSI architecture to perform combined multiply-accumulate, divide, and square root operations is proposed. The circuit is highly regular, requires only minimal control, and can be pipelined right down to the bit level. The system can also be reconfigured on every cycle to perform one or more of these operations. The throughput rate for each operation is the same and is wordlength independent. This is achieved using redundant arithmetic. With current CMOS technology, throughput rates in excess of 80 million operations per second are expected.
We present a discussion of methods based on the complex cross-spectrum and the application of these methods to the analysis of speech. The cross spectral methods developed here are an extension of methods developed in...
详细信息
We present a discussion of methods based on the complex cross-spectrum and the application of these methods to the analysis of speech. The cross spectral methods developed here are an extension of methods developed in the 1980's by one of the authors for accurately estimating stationary and cyclo-stationary parameters of signals buried deep in the noise. Since speech is non-stationary and therefore supports very little integration, the methods have been re-developed to address issues such as non-stationarity, harmonic structures and rapidly changing resonance Cross-spectral methods are presented as complex valued time-frequency surface methods which provide signal parameter estimation by taking advantage of signal structure. These methods have proven to be very powerful.
In many applications (radar, communication, plasma physics) the signal of interest is sinusoidal and is hidden in non-white noise. The multi-window method of spectrum estimation gives a constant false alarm test for t...
详细信息
ISBN:
(纸本)0819406945
In many applications (radar, communication, plasma physics) the signal of interest is sinusoidal and is hidden in non-white noise. The multi-window method of spectrum estimation gives a constant false alarm test for the presence of a sinusoid in a time series if the noise can be assumed Gaussian. In this paper we generalize the method to an array and study the resulting test. Expressions for the probabilities of detection and of false alarm are obtained analytically and receiver operation characteristic curves are computed for a particular scenario under different conditions.
Adaptive array systems require the periodic solution of the well-known w = (R) over tilde (-1)v equation in order to compute optimum adaptive array weights. The covariance matrix (R) over tilde is estimated by forming...
详细信息
ISBN:
(纸本)0819441880
Adaptive array systems require the periodic solution of the well-known w = (R) over tilde (-1)v equation in order to compute optimum adaptive array weights. The covariance matrix (R) over tilde is estimated by forming a product of noise sample matrices X : (R) over tilde = (XX)-X-H. The operations-count cost of performing the required matrix inversion in real time can be prohibitively high for a high bandwidth system with a large number of sensors. Specialized hardware may be required to execute the requisite computations in real time. The choice of algorithm to perform these computations must be considered in conjunction with the hardware technology used to implement the computation engine. A systolic architecture implementation of the Givens rotation method for matrix inversion was selected to perform adaptive weight computation. The bit-level systolic approach enables a simple ASIC design and a very low power implementation. The bit-level systolic architecture must be implemented with fixed-point arithmetic to simplify the propagation of data through the computation cells. The Givens rotation approach has a highly parallel implementation and is ideally suited for a systolic implementation. Additionally, the adaptive weights are computed directly from the sample matrix X in the voltage domain, thus reducing the required dynamic range needed in carrying out the computations. An analysis was performed to determine the required fixed-point precision needed to compute the weights for an adaptive array system operating in the presence of interference. Based on the analysis results. it was determined that the precision of a floating-point computation can be well approximated with a 13-bit to 19-bit word length fixed point computation for typical system jammer-to-noise levels. This property has produced an order-of-magnitude reduction in required hardware complexity. A synthesis-based ASIC design process was used to generate preliminary layouts. These layouts were used t
Distributed sensor networks have been proposed for a wide range of applications. In this paper, our goal is to locate a wideband source, generating both acoustic and seismic signals, using both seismic and acoustic se...
详细信息
Distributed sensor networks have been proposed for a wide range of applications. In this paper, our goal is to locate a wideband source, generating both acoustic and seismic signals, using both seismic and acoustic sensors. For a far-field acoustic source, only the direction-of-arrival (DOA) in the coordinate system of the sensors is observable. We use the approximate Maximum-Likelihood (AML) method for DOA estimations from several acoustic arrays. For a seismic source, we use data collected at a single tri-axial accelerometer to perform DOA estimation. Two seismic DOA estimation methods, the eigen-decomposition of the sample covariance matrix method and the surface wave method are used. Field measurements of acoustic and seismic signals generated by vertically striking a heavy metal plate placed on the ground in an open field are collected. Each acoustic array uses four low-cost microphones placed in a square configuration and separated by one meter. The microphone outputs of each array are collected by a synchronized A/D recording system and processed locally based on the AML algorithm for DOA estimation. An array of six tri-axial accelerometers arranged in two rows whose outputs are fed into an ultra low power and high resolution network-aware seismic recording system. Field measured data from the acoustic and seismic arrays show the estimated DOAs and consequent localizations of the source are quite accurate and useful. Beamforming, Source localization,.
暂无评论