作者:
Cao, YCSridharan, SMoody, MSpeech Research Lab.
Signal Processing Research Centre School of Electrical and Electronic Systems Engineering Queensland University of Technology Brisbane QLD QLD4001 GPO BOX 2434 Australia
A microphone array system with multi-stage processing for speech enhancement is presented in this paper. Two beamformers with uniform directional patterns, one aimed at the target source and the other at the interferi...
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A microphone array system with multi-stage processing for speech enhancement is presented in this paper. Two beamformers with uniform directional patterns, one aimed at the target source and the other at the interfering sources, convert the multi-channel inputs into two data sequences. A novel microphone array structure with a small aperture has been designed to obtain the dual beamformers. The outputs of the two beamformers are then presented to a post-processing stage to further improve the quality and intelligibility of the speech signal. The post-processing stage can be selected from one of three different algorithms that are presented, which are suitable for different acoustic environments. Applications for such a system include hands-free telephony, teleconferencing and also special situations where speech signals must be picked up in an extremely noisy acoustic environment in which the microphones are hidden (e.g. in a forensic covert recording system).
A novel method for designing the FIR filter in the Hammerstein model for power estimation of complex-valued signals is *** enables a computationally effective optimal power estimation with a prescribed delay in minimu...
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A novel method for designing the FIR filter in the Hammerstein model for power estimation of complex-valued signals is *** enables a computationally effective optimal power estimation with a prescribed delay in minimum mean squared error sense,a great reduction of the estimation bias which is inherent in power *** are given by assuming a constant input signal and a Rayleigh distributed input fading signal respectively,both signals are complex-valued and corrupted by Gaussian noise.
The solutions to the power projection, transportation, and operational needs of the Navy as it faces the 21st century must account for reduced manning levels. This leads naturally to increased use of computers, automa...
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The solutions to the power projection, transportation, and operational needs of the Navy as it faces the 21st century must account for reduced manning levels. This leads naturally to increased use of computers, automation, and intelligent systems in the concept and design of the next generation of ships. In addition to the acknowledged hardware needs, the problem of autonomic and autonomous control of shipboard systems and missions are amenable to and will, in fact, require software solutions. Despite current technology, large, reliable software systems are difficult to achieve because correctness in requirements analysis, design, implementation, testing, modification, and maintenance of software are difficult. Software is also difficult to quantize and display;hence, the effort and costs involved in its development are easily underestimated. This paper describes an approach to the problem of providing structure, in the form of a software architecture, to the software performing autonomous control of missions and their related tasks. In concert with the need to reduce complexity, the architecture must support simple, rapid reconfiguration of code should vehicle capabilities or mission requirements change. Building upon recent efforts with control of Autonomous Underwater Vehicles (AUVs), we propose a tri-level control system architecture called the Rational Behavior Model (RBM) as an approach to autonomous and autonomic control of surface ship missions and systems.
In this paper, two fast algorithms are developed to compute a set of parameters, called M(i)'s, of weighted median filters for integer weights and real weights, respectively. The M(i)'s, which characterize the...
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In this paper, two fast algorithms are developed to compute a set of parameters, called M(i)'s, of weighted median filters for integer weights and real weights, respectively. The M(i)'s, which characterize the statistical properties of weighted median filters and are the critical parameters in designing optimal weighted median filters, are defined as the cardinality of the positive subsets of weighted median filters. The first algorithm, which is for integer weights, is abo ut four times faster than the existing algorithm. The second algorithm, which applies for real weights, reduces the computational complexity significantly for many applications where the symmetric weight structures are assumed. Applications of these new algorithms include design of optimal weighted filters, computations of the output distributions, the output moments, and the rank selection probabilities, and evaluation of noise attenuation for weighted median filters.
The concept of eigen decomposition for two-channel signal separation, a novel method of enhancing the desired signal corrupted by interference, is described. The method uses two observations, which come from a pair of...
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This paper describes an auto-seeking microphone array consisting of novel multiple processing stages for speech acquisition. The array automatically detects the speech in the presence of noise and tracks the speech so...
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This paper describes an application specific DSP core designed to be used in a CCITT 32 kbit/s G.726 Adaptive Differential Pulse Code Modulation (ADPCM) codec. The instruction set architecture and the programming mode...
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This paper describes an application specific DSP core designed to be used in a CCITT 32 kbit/s G.726 Adaptive Differential Pulse Code Modulation (ADPCM) codec. The instruction set architecture and the programming model of the DSP core were derived from an algorithm profile and complexity analysis and the core was implemented using VHDL and logic synthesis. Architecture design efforts were concentrated on finding the minimum amount of hardware resources which could implement the required functionality within the clock cycle count limit. The result is a Harvard architecture processor core which can be used to implement the 32 kbit/s G.726 ADPCM encoding/decoding functions with very modest external instruction and data memory requirements. In a typical configuration the processor can perform a full encode/decode operation for one sample in less than 1100 clock cycles. A gate-level implementation of less than 4000 gates of silicon area was created using logic synthesis for a standard cell technology.
A new technique is presented for the characterization of impulsive interference with /spl alpha/-stable processes. The proposed model is constructed by estimating the /spl alpha/-stable distribution parameters using t...
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A new technique is presented for the characterization of impulsive interference with /spl alpha/-stable processes. The proposed model is constructed by estimating the /spl alpha/-stable distribution parameters using the empirical characteristic function. Characteristic function based methods have been shown to yield the best performance but are plagued by the amount of computation required. The new parameter estimation algorithm is shown to achieve the same level of performance as other characteristic function based methods while greatly reducing the amount of computation required.
A layered motion estimation scheme using fuzzy clustering is introduced in this paper. Once motion estimation is performed, a lab.l smoothing is applied by using a modified objective function that takes into account s...
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A layered motion estimation scheme using fuzzy clustering is introduced in this paper. Once motion estimation is performed, a lab.l smoothing is applied by using a modified objective function that takes into account spatial continuity. This allows to suppress noisy classes scattered over the whole image.
This paper discusses a discrete-time modeling technique where the length of time delays can be arbitrarily adjusted. The new system is called a fractional delay waveguide model (FDWM). Formerly, FDWMs have only been i...
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This paper discusses a discrete-time modeling technique where the length of time delays can be arbitrarily adjusted. The new system is called a fractional delay waveguide model (FDWM). Formerly, FDWMs have only been implemented with FIR-type fractional delay filters. We show how an FDWM can be implemented using allpass filters. We use low-order allpass filters that are maximally-flat approximations of the ideal delay. The advantages of the allpass approach are computational efficiency and reduced approximation error. The proposed structure can be applied to discrete-time modeling of acoustic tubes, such as the human vocal tract or resonators of musical instruments.
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