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Signals, Systems and Computers, 1996. Conference Record of the Thirtieth Asilomar Conference on

Date 3-6 Nov. 1996

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  • A parallel two-dimensional block adaptive filter with reduced computational complexity

    Publication Year: 1996, Page(s):3 - 7 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (353 KB)

    Two-dimensional (2-D) adaptive digital filters (ADFs) for 2-D signal processing have become a fascinating area of the adaptive signal processing. However, conventional 2-D FIR ADFs require a lot of computations. For example, the TDLMS requires 2N/sup 2/ multiplications per pixel. We propose a new 2-D adaptive filter using the FFTs. The proposed adaptive filter carries out the fast convolution usin... View full abstract»

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  • Adaptive octave filter bank with adaptive magnitude and phase

    Publication Year: 1996, Page(s):8 - 12 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (409 KB)

    The theory and performance of an adaptive octave filter bank is examined. This filter structure is derived from the discrete cosine transform filter, which is itself a generalization of the frequency sampling filter that includes phase. In previous work, the bandpass filters were uniformly spaced in frequency. In this paper, the bandpasses are octavely space in frequency. The previous work resulte... View full abstract»

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  • Adaptive mean/median filtering

    Publication Year: 1996, Page(s):13 - 16 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (283 KB)

    The use of median and averaging filters is fairly routine in signal processing applications. One problem in using such algorithms is the lack of objective criteria by which to decide whether an averager or a median filter is more appropriate. We formulate an L/sub p/ (1/spl les/p/spl les/2) normed filter where p is chosen as a function of the kurtosis of the residual vector; we restrict attention ... View full abstract»

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  • Derivation of stability condition for recursive second order polynomial filters

    Publication Year: 1996, Page(s):17 - 20 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (302 KB)

    In this paper, a stability condition for a time-invariant recursive second order polynomial filter is presented. Stability conditions of recursive nonlinear filters are input dependent. When the input signal is bounded by the stability condition, the output signal of the presented recursive nonlinear filter is assured to be bounded which guarantees the stability of the structure. View full abstract»

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  • Design of FIR filters with magnitude specifications

    Publication Year: 1996, Page(s):21 - 23 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (253 KB)

    In this paper, we present a method for the design of an FIR filter that minimizes the Chebyshev error in the magnitude frequency domain. The method exhibits desirable properties similar to those characterizing the Parks-McClellan algorithm and requires less than seven iterations to solve the nonlinear filter design problem. The O(N/sup 2/) iterative method yields filters that are 40% better than t... View full abstract»

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  • The analysis of structurally constrained minimum mean-square error block matrix filters

    Publication Year: 1996, Page(s):24 - 28 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (415 KB)

    We consider here the problem of applying system requirements in SISO FIR block matrix filters, their least-squares error formulation with a look towards improving computational efficiency, and their eventual performance characterization. It is shown that the proposed least squares formulation can be applied to structural requirements in general and that the approach taken in this paper is adequate... View full abstract»

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  • Specifications of ideal prototype filters for designing linear phase FIR filters

    Publication Year: 1996, Page(s):29 - 33 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (335 KB)

    To design a linear phase FIR filter using a window technique, the infinite impulse response of an ideal filter to approximate a desired specifications must be truncated to a finite length. The parameters associated with this technique are the length of the impulse response and the type of the truncation window. We discuss another parameter, the specification of the frequency response of the ideal ... View full abstract»

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  • Prefilter design using the singular value decomposition for MIMO equalization

    Publication Year: 1996, Page(s):34 - 38 vol.1
    Cited by:  Patents (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (518 KB)

    This paper describes a new prefilter design method for MIMO communication channels with equalizers. The prefilter is designed in the frequency domain to make the channel easier to equalize. We apply the singular value decomposition (SVD) of the channel frequency response to design the prefilter. The new prefilter achieves a performance improvement at high signal to noise ratio (SNR) while keeping ... View full abstract»

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  • Array antenna applications for neural beamforming

    Publication Year: 1996, Page(s):40 - 44 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (518 KB)

    This paper is a summary of our research on applying neural network based signal processing to array antenna problems which we call neural beamforming. The objective is to train the network at certain training angles within the antenna field of view so that it can perform the desired antenna function with arrays which cost less to manufacture. We are also concerned with array operation in adverse e... View full abstract»

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  • Application of microphone array for speech coding in noisy environment

    Publication Year: 1996, Page(s):45 - 49 vol.1
    Cited by:  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (474 KB)

    To improve speech intelligibility and quality for coding, an array preprocessor is proposed to enhance noisy speech. The microphone array data is processed with a robust quadratically and linearly constrained minimum variance algorithm. The processor nulls noise and/or interference power from arbitrary spatial and frequency locations and maintains speech from desired locations, thus increasing the... View full abstract»

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  • Conference Record Of The Thirtieth Asilomar Conference Signals, Systems & Computers [front matter]

    Publication Year: 1996, Page(s):iii - xxii
    Request permission for commercial reuse | PDF file iconPDF (1059 KB)
    Freely Available from IEEE
  • Array pattern synthesis for satellite communications on-the-move

    Publication Year: 1996, Page(s):50 - 54 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (487 KB)

    We describe the synthesis of transmit beampatterns for a multi-band array of nonuniformly spaced spiral antennas for use in geosynchronous satellite communications. Due to element size the minimum inter-element spacing is more than a half-wavelength, and the spiral elements have directional radiation patterns, complicating the synthesis problem. We describe the application of three known synthesis... View full abstract»

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  • Performance of antenna arrays with fading signals

    Publication Year: 1996, Page(s):55 - 59 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (427 KB)

    We study the effect of fading on estimating the antenna array response, and subsequently separating and estimating the unknown data streams. The results are presented in the form of output signal to interference ratio (SIR) and output signal to noise ratio (SNR). We obtain closed form expressions for the average output SNR and SIR for Rayleigh, Rician and Nagakami fading. It is shown that in the p... View full abstract»

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  • An experimental multisensor receiver for DS/CDMA system

    Publication Year: 1996, Page(s):60 - 64 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    This paper presents the experimental study of a two sensor terminal for a satellite DS/CDMA system. The receiver uses two circular polarized microstrip antennas. A spatial blind processing is investigated. The performance of the two receivers is studied through measurements for different signals scenarios, in order to demonstrate the interest of this type of receivers. In particular, the influence... View full abstract»

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  • Optimal weight vectors for broadcast channels

    Publication Year: 1996, Page(s):65 - 69 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    In a multi-transmitter broadcast system, the weight vector for each message signal can provide an additional degree-of-freedom for signal enhancement and interference suppression by taking advantage of the spatial diversity among the users. To date, the design of the optimal weight vectors which maximize the overall channel capacity is still an open problem. The main reason is attributed to the fa... View full abstract»

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  • Exploiting linear block codes for blind co-channel interference reduction in TDMA based wireless communication systems

    Publication Year: 1996, Page(s):70 - 74 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    In this paper, we present a novel array processing technique for co-channel interference reduction for TDMA based mobile satellite communication systems using linear block codes. This technique combines least squares projection with syndrome detection (LSPSD) to compute the optimum multi-antenna linear receiver for a signal of interest (SOI) encoded with a linear block coding scheme. The algorithm... View full abstract»

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  • Improving the performance of adaptive arrays in nonstationary environments through data-adaptive training

    Publication Year: 1996, Page(s):75 - 79 vol.1
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (476 KB)

    Adaptive array algorithms based on sample matrix inversion require the availability of a secondary data set to "train" the adaptive filter. Numerous data-independent rules have been proposed for selecting this training data. However, such rules often perform poorly in highly nonstationary environments. In this paper, we present data-adaptive techniques for selecting the training data. The techniqu... View full abstract»

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  • Super-resolution of imagery acquired through turbulent atmosphere

    Publication Year: 1996, Page(s):81 - 85 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (514 KB)

    The resolution of images is determined by the processes of diffraction. Recently, practical algorithms have emerged that are capable of recovering spatial frequency detail that lies beyond the diffraction limit of an image sensor. In this presentation we shall briefly review some of the aspects of super-resolution algorithms and then discuss the extension of same to images obtained through a turbu... View full abstract»

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  • On the use of mapping operators in SAR and SAS

    Publication Year: 1996, Page(s):86 - 89 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (345 KB)

    The process of reconstructing a two-dimensional image of the earth's surface or the sea floor from a sequence of pulse echoes collected by a synthetic aperture radar (SAR) or sonar (SAS) is well established. There are differences between radar and sonar mainly stemming from the much slower speed of sound propagation in water compared with that of electromagnetic propagation in air. Of all the stri... View full abstract»

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  • Image restoration based template matching for multichannel restoration of image sequences

    Publication Year: 1996, Page(s):90 - 94 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (827 KB)

    It has been demonstrated that multichannel restoration of motion compensated images sequences is very effective when good estimates of the displacement vector field (DVF) are available. In this paper two new stochastic algorithms for template-matching based DVF estimation are proposed. These algorithms are based on the relationship of the template-matching and the image restoration problems. Exper... View full abstract»

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  • Restoration from partially-known blur using an expectation-maximization algorithm

    Publication Year: 1996, Page(s):95 - 99 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (425 KB)

    In this paper we address the problem of image restoration when the point-spread function (PSF) of the imaging process is not known exactly, a situation which arises regularly in practice. The algorithm based on the expectation-maximization (EM) algorithm is proposed which has the capability to identify the unknown statistics of the image and the image-dependent noise while restoring the image. The... View full abstract»

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  • Motion-compensated interpolation of untransmitted frames in compressed video

    Publication Year: 1996, Page(s):100 - 104 vol.1
    Cited by:  Papers (4)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (427 KB)

    At low bit rates, most video coders drop frames from the original video. Motion-compensated interpolation (MCI) requires no additional bandwidth and can interpolate the missing frames. Existing MCI methods, developed for uncompressed video, are computationally demanding and require additional motion estimation (ME). By exploiting the motion field already present in the coded video, the MCI algorit... View full abstract»

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  • Lossy adaptive coding of motion vectors with global camera motion compensation

    Publication Year: 1996, Page(s):105 - 108 vol.1
    Cited by:  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (315 KB)

    We propose a motion estimation and coding scheme that combines global camera motion estimation with a scene adaptive coder based on a quadtree structure with entropy-constrained vector quantization (ECVQ). Global camera motion parameters are first estimated before the local motion estimation. A quadtree structure is then constructed that finds the best block size to perform adaptive local motion e... View full abstract»

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  • Blind separation of images

    Publication Year: 1996, Page(s):109 - 113 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (619 KB)

    The problem of separating two uncorrelated images from two observed mixtures of these images is considered in this paper. Each observed image is modeled as the sum of one original image and another original image filtered through a two dimensional FIR filter. An algorithm, to estimate these filters, is presented from a separation structure and a minimization of a criterion based on second order st... View full abstract»

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  • High quality alias free image rotation

    Publication Year: 1996, Page(s):115 - 119 vol.1
    Cited by:  Papers (4)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (525 KB)

    This paper presents new algorithms for the rotation of images. The primary design criteria for these algorithms is very high quality. Common methods for image rotation, including convolutional and separable approaches, are examined and shown to exhibit significant high frequency aliasing problems. A new resampling filter design methodology is presented which minimizes the problem for conventional ... View full abstract»

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