Recently, cepstral analysis based on second order statistics and homomorphic filtering techniques have been used in the adaptive decomposition of overlapping, or otherwise, and noise contaminated ECG complexes of moth...
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ISBN:
(纸本)0819422347
Recently, cepstral analysis based on second order statistics and homomorphic filtering techniques have been used in the adaptive decomposition of overlapping, or otherwise, and noise contaminated ECG complexes of mothers and fetals obtained by a transabdominal surface electrodes connected to a monitoring instrument, an interface card, and a PC. Differential time delays of fetal heart beats measured from a reference point located on the mother complex after transformation to cepstra domains are first obtained and this is followed by fetal heart rate variability computations. Homomorphic filtering in the complex cepstral domain and the subuent transformation to the time domain results in fetal complex recovery. However, three problems have been identified with second-order based cepstral techniques that needed rectification in this paper. These are (1) errors resulting from the phase unwrapping algorithms and leading to fetal complex perturbation, (2) the unavoidable conversion of noise statistics from Gaussianess to non-Gaussianess due to the highly non-linear nature of homomorphic transform does warrant stringent noise cancellation routines, (3) due to the aforementioned problems in (1) and (2), it is difficult to adaptively optimize windows to include all individual fetal complexes in the time domain based on amplitude thresholding routines in the complex cepstral domain (i.e. the task of `zooming' in on weak fetal complexes requires more processing time). The use of third-order based high resolution differential cepstrum technique results in recovery of the delay of the order of 120 milliseconds.
The design, implementation, and performance of a low-cost, real-time DSP system for source location is discussed. The system consists of an 8-element electret microphone array connected to a signalogic DSP daughterboa...
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Images and signals can be characterized by representations invariant to time shifts, spatial shifts, frequency shifts, and scale changes as the situation dictates. Advances in time-frequency analysis and scale transfo...
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ISBN:
(纸本)0819422347
Images and signals can be characterized by representations invariant to time shifts, spatial shifts, frequency shifts, and scale changes as the situation dictates. Advances in time-frequency analysis and scale transform techniques have made this possible. The next step is to distinguish between invariant forms representing different classes of image or signal. Unfortunately, additional factors such as noise contamination and `style' differences complicate this. A ready example is found in text, where letters and words may vary in size and position within the image segment being examined. Examples of complicating variations include font used, corruption during fax transmission, and printer characteristics. The solution advanced in this paper is to cast the desired invariants into separate subspaces for each extraneous factor or group of factors. The first goal is to have minimal overlap between these subspaces and the second goal is to be able to identify each subspace accurately. Concepts borrowed from high-resolution spectral analysis, but adapted uniquely to this problem have been found to be useful in this context. Once the pertinent subspace is identified, the recognition of a particular invariant form within this subspace is relatively simple using well-known singular value decomposition techniques.
The aim of the paper is to estimate the contribution of the polarization diversity in high frequency (3 - 30 MHz) direction finding systems. We first describe the peculiarities of H.F. propagation and the resulting si...
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ISBN:
(纸本)0819416207
The aim of the paper is to estimate the contribution of the polarization diversity in high frequency (3 - 30 MHz) direction finding systems. We first describe the peculiarities of H.F. propagation and the resulting signal model involved in computer simulations. Next, we analyze the behavior of some particular direction finding systems using linear and circular geometries and polarization diversity. Some algorithms (non linear frequential analysis, M.U.S.I.C.) are tested in several conditions (narrowband or broadband signals, polarization filtering reiterated or no, sub-sampling). Theoretical and experimental results show that polarization diversity based upon the knowledge of the antenna complex responses improves greatly the efficiency of direction finding.
This conference proceedings contains 39 papers. The topics discussed are algorithmic engineering, algorithm implementations, parallel processing systems, pipeline processing systems, signalprocessingarchitectures, a...
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ISBN:
(纸本)081940943X
This conference proceedings contains 39 papers. The topics discussed are algorithmic engineering, algorithm implementations, parallel processing systems, pipeline processing systems, signalprocessingarchitectures, array processing and direction finding, time frequency signal analysis, higher-order spectra, signal theory, wavelets, and time-frequency distributions.
The NRL FLEX processor architecture is designed for real-time radar signalprocessing and was described at last year's conference in the context of its original application, the Point Defense Demonstration Radar p...
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ISBN:
(纸本)081940943X
The NRL FLEX processor architecture is designed for real-time radar signalprocessing and was described at last year's conference in the context of its original application, the Point Defense Demonstration Radar project at NRL. This paper describes the current status of the processor and the application of the same architecture to a new problem which requires a different board configuration to satisfy a different set of latency and data flow requirements.
The Volume contains 44 conference papers. The topic covered include Toeplitz matrices, time-frequency distribution and nonstationary signals, bit-level systolic arrays and computer arithmetic, radar signalprocessing,...
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ISBN:
(纸本)0819406945
The Volume contains 44 conference papers. The topic covered include Toeplitz matrices, time-frequency distribution and nonstationary signals, bit-level systolic arrays and computer arithmetic, radar signalprocessing, signal estimation, array processing and beamforming.
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