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Acoustics, Speech, and Signal Processing, 2001. Proceedings. (ICASSP '01). 2001 IEEE International Conference on

Date 7-11 May 2001

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  • 2001 IEEE International Conference on Acoustics, Speech, and Signal Processing Proceedings [front matter]

    Publication Year: 2001 , Page(s): i - xci
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  • An iterative solution for the optimal poles in a Kautz series

    Publication Year: 2001 , Page(s): 3949 - 3952 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    Kautz series allow orthogonal series expansion of finite-energy signals defined on a semi-infinite axis. The Kautz series consists of orthogonalized exponential functions or sequences. This series has as free parameters an ordered set of poles, each pole associated with an exponential function or sequence. For reasons of approximation and compact representation (coding), an appropriate set of ordered poles is therefore convenient. An iterative procedure to establish the optimal parameters according to an enforced convergence criterion is introduced. View full abstract»

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  • Some of the abstracts listed in the student forum reflect work that was not published in the ICASSP proceedings

    Publication Year: 2001 , Page(s): 4013 - 4053
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  • Author index

    Publication Year: 2001 , Page(s): 4055 - 4068
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  • Biorthogonal Butterworth wavelets

    Publication Year: 2001 , Page(s): 3645 - 3648 vol.6
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    We present a new family of biorthogonal wavelet transforms and a related library of biorthogonal symmetric wavelets. For the construction we use the interpolatory discrete splines which enable us to design perfect reconstruction filter banks related to the Butterworth filters. The construction is performed in a “lifting” manner. The proposed scheme is based on interpolation and, as such, it involves only samples of signals and it does not require any use of quadrature formulas. These filters have linear phase property. The filters yield perfect frequency resolution View full abstract»

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  • Instantaneous frequency estimation by using time-frequency distributions

    Publication Year: 2001 , Page(s): 3521 - 3524 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    Estimation of the instantaneous frequency by using quadratic distributions from the general Cohen class is analyzed. Frequency modulated signals corrupted with a white stationary noise are considered. An expression for the variance is derived. It is shown that the variance is closely related to the non-noisy distribution of a predefined signal View full abstract»

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  • A fractional Gabor transform

    Publication Year: 2001 , Page(s): 3529 - 3532 vol.6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    We present a fractional Gabor expansion on a general, non-rectangular time-frequency lattice. The traditional Gabor expansion represents a signal in terms of time- and frequency-shifted basis functions, called Gabor logons. This constant-bandwidth analysis results in a fixed, rectangular time frequency plane tiling. Many of the practical signals require a more flexible, non-rectangular time-frequency lattice for a compact representation. The proposed fractional Gabor expansion uses a set of basis functions that are related to the fractional Fourier basis and generate a non-rectangular tiling. The completeness and bi-orthogonality conditions of the new Gabor basis are discussed View full abstract»

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  • An efficient algorithm for FIR filter bank completion

    Publication Year: 2001 , Page(s): 3629 - 3632 vol.6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    This paper presents an algorithm for designing an FIR paraunitary filter bank when one or several filters are given. The algorithm is based on the properties of the balanced state-space representation of the polyphase matrix. We show that this representation may be computed via a single RQ decomposition thus gaining significant efficiency with respect to previous work. Application of the algorithm to signal-adapted filter banks is also discussed View full abstract»

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  • Optimal design method for FIR filter with discrete coefficients based on integer semi-infinite linear programs

    Publication Year: 2001 , Page(s): 3805 - 3808 vol.6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    The purpose of the paper is to propose a new design method of FIR filters with discrete coefficients considering optimality. In the proposed method, the design problem of FIR filters is formulated as a mixed integer semi-infinite linear programming problem (MISILP), which can be solved by a branch and bound technique. Then, it is possible to obtain the optimal discrete coefficients, and the optimality of the obtained solution can be guaranteed. It was confirmed that optimal coefficients of a linear phase FIR filter with discrete coefficients could be designed in reasonable computational time with sufficient precision based on the results of computational experiments View full abstract»

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  • Matrix formulation of a universal microbial transcript profiling system

    Publication Year: 2001 , Page(s): 3453 - 3456 vol.6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB) |  | HTML iconHTML  

    DNA chips and microarrays are used to profile gene transcription. Unfortunately, the initial fabrication cost for a chip and the reagent costs to amplify thousands of open reading frames for a microarray are over $100K for a typical 4 Mbase bacterial genome. To avoid these expensive steps, a matrix formulation of a universal hybrid chip-microarray approach to transcript profiling is demonstrated for synthetic data. Initial considerations for application to the 4.3 Mbase bacterium Yersinia pestis are also presented. This approach can be applied to arbitrary bacteria by recalculating a matrix and pseudoinverse. This approach avoids the large upfront expenses associated with DNA chips and microarrays View full abstract»

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  • Instantaneous frequency estimation using discrete evolutionary transform for jammer excision

    Publication Year: 2001 , Page(s): 3525 - 3528 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    We propose a method - based on the discrete evolutionary transform (DET) - to estimate the instantaneous frequency of a signal embedded in noise or noise-like signals. The DET provides a representation for non-stationary signals and a time-frequency kernel that permit us to obtain the time-dependent spectrum of the signal. We show the instantaneous phase and the corresponding instantaneous frequency (IF) can also be computed from the evolutionary kernel. Estimation of instantaneous frequency is of general interest in time-frequency analysis, and of special interest in the excision of jammers in the direct sequence spread spectrum. Implementation of the IF estimation is done by masking and a recursive nonlinear correction procedure. The proposed estimation is valid for monocomponent as well as multicomponent signals in the noiseless and noisy situations. Its application to jammer excision in direct sequence spread spectrum communication is considered as an important application. The estimation procedure is illustrated with several examples View full abstract»

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  • Perfect reconstruction integer-modulated filter banks

    Publication Year: 2001 , Page(s): 3605 - 3608 vol.6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    We present design methods for perfect reconstruction (PR) integer-modulated filter banks, including biorthogonal (low-delay) filter banks. Both the prototype filter and the modulation sequences are composed of integers, thus allowing efficient hardware implementations. To derive such filter banks, we first extend the PR conditions known for cosine modulation to other, more general, modulation schemes. We present solutions where the PR conditions on the prototype and the modulation are entirely decoupled and where some simple coupling is introduced. The conditions are derived for both even and odd numbers of channels. Design examples are presented for both cases View full abstract»

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  • Analysis of non-stationary mode coupling by means of wavelet-bicoherence

    Publication Year: 2001 , Page(s): 3581 - 3584 vol.6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    We present a definition of wavelet bicoherence based on wavelet polyspectra. We propose a simple estimator for wavelet bicoherence, and discuss its statistical properties. In particular it is shown that wavelet bicoherence estimation has a larger number of effective degrees of freedom than traditional Fourier-based bicoherence estimation. The proposed estimator is applied to detection of coherent couplings in rocket measurements from the ionospheric E-region. It is concluded that wavelet bicoherence is a tool well-suited for analysis of non-stationary mode coupling View full abstract»

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  • Fast algorithm for least squares 2D linear-phase FIR filter design

    Publication Year: 2001 , Page(s): 3809 - 3812 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    We develop a new method for weighted least squares 2D linear-phase FIR filter design. It poses the problem of filter design as the problem of projecting the desired frequency response onto the subspace spanned by an appropriate orthonormal basis. We show how to compute the orthonormal basis efficiently in the cases of quadrantally symmetric filter design and centro-symmetric filter design. The design examples show that the proposed method is faster than a conventional weighted least squares filter design method. Also, the amount of storage required to compute the filter coefficients is greatly reduced View full abstract»

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  • Calculation of the Kullback-Leibler distance between point process models

    Publication Year: 2001 , Page(s): 3437 - 3440 vol.6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    We have developed a method for quantifying neural response changes in terms of the Kullback-Leibler distance between the intensity functions for each stimulus condition. We use empirical histogram estimates to characterize the intensity function of the neural response. A critical factor in determining the histogram estimates is selection of bin-width. We analytically derive the Kullback-Leibler distance between two Poisson processes and two dead time modified Poisson processes in terms of the bin-width selected. Our results show that, for constant intensity processes having the same number of expected counts, the distance between the dead time modified processes is larger than between the Poisson processes View full abstract»

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  • Sampling criterion for nonlinear systems with a bandpass input

    Publication Year: 2001 , Page(s): 3457 - 3460 vol.6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    Sampling requirements for nonlinear systems with a bandpass input are developed. It is well known that the output of a nonlinear system may have a larger bandwidth than that of the input. According to the Nyquist sampling theorem, the sampling rate needs to be at least twice the maximum frequency of the output to avoid aliasing. However, if the input is a bandpass signal, the spectrum of the output is usually distributed over several frequency bands. In this case, using the bandpass sampling concept, it is possible to sample the output at a much lower rate. Conditions for such a lower sampling rate to exist are derived for nonlinear systems up to the third order. Supporting computer simulation is also provided View full abstract»

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  • Linear matrix inequality formulation of spectral mask constraints

    Publication Year: 2001 , Page(s): 3813 - 3816 vol.6
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB) |  | HTML iconHTML  

    The design of a finite impulse response filter often involves a spectral `mask' which the magnitude spectrum must satisfy. This constraint can be awkward because it yields an infinite number of inequality constraints (two for each frequency point). In current practice, spectral masks are often approximated by discretization, but we show that piecewise constant masks can be precisely enforced in a finite and convex manner via linear matrix inequalities. This facilitates the formulation of a diverse class of filter and beamformer design problems as semidefinite programmes. These optimization problems can be efficiently solved using recently developed interior point methods. Our results can be considered as extensions to the well-known positive-real and bounded-real lemmas from the systems and control literature View full abstract»

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  • High resolution time-frequency analysis by fractional domain warping

    Publication Year: 2001 , Page(s): 3553 - 3556 vol.6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    A new algorithm is proposed to obtain very high-resolution time-frequency analysis of signal components with curved time-frequency supports. The proposed algorithm is based on the fractional Fourier domain warping concept introduced in this work. By integrating this warping concept to the recently developed directionally smoothed Wigner distribution algorithm (Ozdemir et al., 2000), the high performance of that algorithm on linear, chirp-like components is extended to signal components with curved time-frequency supports. The main advantage of the algorithm is its ability to suppress not only the cross-cross terms, but also the auto-cross terms in the Wigner distribution. For a signal with N samples duration, the computational complexity of the algorithm is O(NlogN) flops for each computed slice of the new time-frequency distribution View full abstract»

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  • Integer fast Fourier transform (INTFFT)

    Publication Year: 2001 , Page(s): 3485 - 3488 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB) |  | HTML iconHTML  

    The concept of integer fast Fourier transform (IntFFT) for approximating the discrete Fourier transform is introduced. Unlike the fixed-point fast Fourier transform (FxpFFT), the new transform has properties that it is an integer-to-integer mapping, power-adaptable and also reversible. A lifting scheme is used to approximate complex multiplications appearing in the FFT lattice structures. Split-radix FFT is used to illustrate the approach for the case of 2N-point FFT. The transform can be implemented by using only bit shifts and additions but no multiplication. While preserving the reversibility, the IntFFT is shown experimentally to yield the same accuracy as the FxpFFT when their coefficients are quantized to a certain number of bits. Complexity of the IntFFT is shown to be much lower than that of the FxpFFT in terms of the numbers of additions and shifts View full abstract»

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  • The design of equiripple matrix filters

    Publication Year: 2001 , Page(s): 3793 - 3796 vol.6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB) |  | HTML iconHTML  

    This paper presents a procedure for deriving linear filters which are based on matrix-vector multiplication instead of linear convolution and which can be designed to match the frequency responses of linear equiripple FIR filters. The magnitude of the matrix filter response is matched to the magnitude response of a given linear FIR filter by solving a set of nonlinear equations numerically using Broyden's method View full abstract»

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  • Sensor arrays in the micro-environment of the brain

    Publication Year: 2001 , Page(s): 3433 - 3436 vol.6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    Technology for recording action potentials from the nervous system has changed in recent years from single or at most two or three neurons to tens of neurons recorded from geometrically precise arrays of recording sites. To fully exploit these research opportunities, signal delivery and processing are key factors. We desire not only to sort the array input into neural channels but to locate neurons with respect to the array so they can be later identified in histology and serve to further decode the activity of each neuron. The distribution of a neuron's signal across the sensor array is predictive of the cell location at least in projection onto the array but also in the dimension above the array. To achieve 3-dimensional locating power, careful estimation of signal strength at each site must be achieved taking into account the distance and the field distortion for all anticipated source positions. Achieving this independent of source strength appears to be feasible View full abstract»

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  • Design of a time-frequency domain matched filter for detection of non-stationary signals

    Publication Year: 2001 , Page(s): 3585 - 3588 vol.6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    A practical and effective approach is proposed to detect a transient or non-stationary signal component of interest from a composite signal waveform. The detection problem has been re-formulated in terms of time-frequency analysis, and, thus, the conventional 1D (ie, time-domain) matched filter approach is extended to the 2D (here, time-frequency domain) optimal filtering. For that purpose, the reduced interference distribution (RID) algorithm, the outer product expansion of the time-frequency distribution, the singular value decomposition (SVD), and a priori available time-frequency information of a signal part of interest are employed to derive a time-frequency domain matched filter by utilizing the singular values of the sampled time-frequency distribution and the corresponding fractions of signal energy. Finally, one real problem of detecting the snare drum sound event from a measured musical signal is considered to demonstrate the performance of the proposed approach View full abstract»

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  • Quantization to maximize SNR in non-orthogonal subband coders

    Publication Year: 2001 , Page(s): 3689 - 3692 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB) |  | HTML iconHTML  

    Recent research in the design of filter banks has shown that non-orthogonal filter banks can potentially provide higher coding gains over orthogonal filter banks. The use of non-orthogonal filter banks, however, poses a difficulty in the quantization of subband signals. The conventional nearest-neighbor (NN) encoding rule for the quantization of subband signals is no longer optimal. We propose two schemes for the quantization of subband signals in non-orthogonal subband coders. An optimal scheme for quantization of subband signals is proposed first. The complexity of the optimal quantization scheme is shown to grow exponentially with the length of the synthesis filters, which motivates the development of low-complexity quantization schemes when the length of the filters in the synthesis filter bank is large. The second quantization technique uses an iterative method to quantize the subband signals such that the mean square error between the input and the reconstructed output signals is minimized View full abstract»

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  • Spatio-temporal signal processing for multisubject functional MRI studies

    Publication Year: 2001 , Page(s): 3441 - 3444 vol.6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB) |  | HTML iconHTML  

    We consider signal estimation for functional MRI studies on multiple subjects. There are two major issues; alignment or registration of images across subjects, and using the multisubject information to capture covariance information; we discuss only the latter. Capturing this covariance information properly can lead to great improvements in statistical efficiency beyond what simple averaging can offer as well as compact description of group features View full abstract»

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  • Recent developments in concrete nondestructive evaluation

    Publication Year: 2001 , Page(s): 3393 - 3396 vol.6
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB) |  | HTML iconHTML  

    Concrete is a multi-phase composite material which is difficult to inspect using conventional ultrasonic techniques, including those that work well on relatively homogeneous materials such as metals. This paper summarizes recent research that makes use of signal processing techniques to overcome ultrasonic inspection difficulties in concrete. Basic findings from several new laboratory-based NDE techniques for concrete are reported. First, the application of split spectrum processing (SSP) is described. The SSP techniques obtains a frequency-diverse ensemble of narrowband signals through a filterbank and recombines them nonlinearly to improve the target visibility. Examples that demonstrate the capability of SSP to reduce coherent noise (clutter) in ultrasonic signals collected from concrete samples are presented. Next, a self-compensating procedure for practical one-sided surface wave transmission measurements on concrete structures is described. The utility of the technique is demonstrated by sensitivity to surface-opening crack depth in concrete slabs. Finally, an approach by which the setting process (stiffness change) in concrete is nondestructively monitored is described. The reflection factor of shear wave pulses at a steel-concrete interface is measured, from which the stiffness change (setting) of the concrete is inferred View full abstract»

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