Voice activity detection (VAD) is still a difficult task in noisy environments since the statistical distributions of speech and non-speech features are heavily overlapped in noisy environments. Considering that speec...
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ISBN:
(纸本)9781424458981
Voice activity detection (VAD) is still a difficult task in noisy environments since the statistical distributions of speech and non-speech features are heavily overlapped in noisy environments. Considering that speech is a special type of acoustic signal that only occupies a small fraction of the whole acoustic space, we have proposed a new speech processing method for VAD by giving constraints on the processing space as a reproducing kernel Hilbert space (RKHS) [I]. In the RIMS, the estimation of the speech was regarded as a functional approximation problem. Via a regularization in the RKHS framework, a target function is learned to approximate the speech signal while the noise component is supposed to be smoothed out. In this framework, we could incorporate the nonlinear mapping functions in the approximation implicitly via a kernel function. The approximation function could capture the nonlinear and high-order statistical structure of the speech. Our VAD algorithm is designed on the basis of the power energy in this regularized RKHS. We have tested its performance on CENSREC-1-C data corpus for VAD task M. In this paper, we quantified its performance on the discriminability for speech and non-speech, and further compared its performance with several classical VAD algorithms. Experimental results showed that the proposed processing for speech enhanced the discriminability between the distributions of speech and non-speech, and got better performance on the VAD task than the classical VAD algorithms.
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.
A systolic array architecture developed as part of an advanced digital signalprocessing (DSP) IRAD is described. The primary goal is to perform general voice-grade digital demodulation algorithms at 16 times faster t...
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ISBN:
(纸本)0818607653
A systolic array architecture developed as part of an advanced digital signalprocessing (DSP) IRAD is described. The primary goal is to perform general voice-grade digital demodulation algorithms at 16 times faster than real time. It must also perform 32-bit floating-point arithmetic. A model that performs this type of digital demodulation currently requires two microcoded DSP boards to operate at real time. It is believed that the proposed architecture could achieve a processing performance factor of 40 over this model.
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.
Ultrasonic testing systems have been widely used in medical and industrial fields, demanding strict requirements for processing speed and re-configurability of the hardware system. This paper presents a prototype of a...
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ISBN:
(纸本)9781467399852
Ultrasonic testing systems have been widely used in medical and industrial fields, demanding strict requirements for processing speed and re-configurability of the hardware system. This paper presents a prototype of a reconfigurable, high performance, low cost and real-time Ultrasonic signal Acquisition and processing (USAP) platform based on Zynq System-on-Chip (SoC). The USAP platform consists of five major components: Multi-level voltage power supply;High voltage pulse generation;Ultrasonic signal acquisition;Sampling control unit and Digital signalprocessing module. The system uses Xilinx Zynq SoC as main processor and controller. It combines both ARM processor and field-programmable gate array (FPGA) on the same chip, which makes the system capable of doing complex system configuration and performing high speed data processing. With this arrangement, the developed system is highly reconfigurable, where software and hardware configuration can be changed on both ARM and FPGA. This paper presents a system design flow of a complete ultrasonic testing system which is capable of acquiring ultrasonic data and performing advancedsignalprocessingalgorithms in realtime.
This paper addresses two key limitations in existing Image signalprocessing (ISP) approaches: the suboptimal performance in low-light conditions and the lack of trainability in traditional ISP methods. To tackle thes...
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ISBN:
(纸本)9798350344868;9798350344851
This paper addresses two key limitations in existing Image signalprocessing (ISP) approaches: the suboptimal performance in low-light conditions and the lack of trainability in traditional ISP methods. To tackle these issues, we propose a novel, trainable ISP framework that incorporates both the strengths of traditional ISP techniques and advanced MultiScale Retinex (MSR) algorithms for night-time enhancement. Our method consists of three primary components: an ISP-based Luminance Harmonization layer to initially optimize luminance levels in RAW data, a deep learning-based MSR layer for nuanced decomposition of image components, and a specialized enhancement layer for both precise, regionspecific luminance enhancement and color denoising. The proposed approach is validated through rigorous experiments on machine vision benchmarks and objective visual quality indicators. Our results demonstrate not only a significant improvement over existing methods but also robust adaptability under diverse lighting conditions. This work offers a versatile ISP framework with promising applications beyond its immediate scope.
In this paper we demonstrate the applicability of advanced digital signalprocessingalgorithms to the analysis of heart sound signals and describe the development of a PDA-based biomedical instrument capable of acqui...
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ISBN:
(纸本)0780384393
In this paper we demonstrate the applicability of advanced digital signalprocessingalgorithms to the analysis of heart sound signals and describe the development of a PDA-based biomedical instrument capable of acquisition, processing, and analysis of heart sounds. Fourier transform-based spectral analysis of heart sounds was carried out first to show the differences in the frequency contents of normal and abnormal heart sounds. As the time-varying nature of heart sounds calls for better techniques capable of analyzing such signals: the Short Time Fourier Transform (STFT) or spectrogram analysis was performed next. This method performed remarkably well in displaying frequency, magnitude, and time information of the heart sounds, providing robust parameters to make accurate diagnosis. With continuous technological advancements in computing and biomedical instrumentation, and the concurrent popularity of handbeld instruments in the medical community, we introduce the concept of PDA-based digital phonocardiography. A prototype system is comprised of a digital stethoscope and a Pocket PC. Mart sounds are recorded and displayed in the Pocket PC screen. advancedsignalprocessingalgorithms are implemented using the combined capabilities of software tools such as LabVIEW and embedded Visual C++.
We describe a fast and efficient algorithm for automatic detection and estimation of the fundamental frequency F0 of a harmonic time-domain signal. The method is based on differentiation of the short time Fourier tran...
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ISBN:
(纸本)0819441880
We describe a fast and efficient algorithm for automatic detection and estimation of the fundamental frequency F0 of a harmonic time-domain signal. The method is based on differentiation of the short time Fourier transform (STFT) phase, which is implemented as a cross-spectral product. In estimating and isolating the fundamental frequency, several enhancement processes are developed and applied to the TF surface to improve the signal quality. We describe the algorithm in detail and demonstrate the processing gain achieved at each step. In addition, we apply the algorithm to human speech to recover the pitch fundamental F0 and report the evaluation of the algorithm's performance on the Western Michigan vowel corpus [3].
Recursive least square (RLS) estimations are used extensively in many signalprocessing and control applications. The least squares estimator w(t) can be found by solving a linear matrix system A(t)w(t) equals d(t) at...
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ISBN:
(纸本)0819419222
Recursive least square (RLS) estimations are used extensively in many signalprocessing and control applications. The least squares estimator w(t) can be found by solving a linear matrix system A(t)w(t) equals d(t) at each adaptive time step t. In this paper, we consider block RLS computations. Our approach is to employ Galerkin projection methods to solve the linear systems. The method generates a Krylov subspace from a set of direction vectors obtained by solving one of the systems and then projects the residuals of other systems orthogonally onto the generated Krylov subspace to get the approximate solutions. The whole process is repeated until all the systems are solved. Both the exponential data weighting infinite memory method and finite memory sliding data window method are used to formulate the equations. In order to speed up the convergence rate of the method, FFT-based preconditioners are also employed. Numerical results are reported to illustrate the effectiveness of the Galerkin projection method for RLS computations.
Concatenation of space-time (ST) coding with orthogonal frequency-division multiplexing (OFDM) has gained much interest recently. In this work, we derive the exact pairwise error probability (PEP) of space-frequency (...
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ISBN:
(纸本)0819450782
Concatenation of space-time (ST) coding with orthogonal frequency-division multiplexing (OFDM) has gained much interest recently. In this work, we derive the exact pairwise error probability (PEP) of space-frequency (SF) codes for MIMO OFDM Systems. Based on the exact PEP, we derive the tighter upper and lower bounds for the PEP. For asymptotically high SNRs, the design criteria for SF codes differ significantly from those for ST codes over flat fading channels. In this paper, by drawing an analogy between SF and ST codes, we show that when the number of receive antennas is large, the minimum Euclidean distance among code words dominates the performance of SF codes. Therefore, SF codes can be optimized by using the Euclidean-distance criterion valid for AWGN channels. Simulation results are given to show that the results valid for a number of receive antennas tending to infinity still provide correct indications when the number of antennas is small.
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