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Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on

Issue 9 • Date Sep 1997

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Displaying Results 1 - 14 of 14
  • Adaptive filtering in cascade form using a fast multichannel RLS algorithm

    Publication Year: 1997 , Page(s): 757 - 762
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    This work proposes an approach to apply least-squares techniques to adaptive FIR filtering in cascade form. A triangular structure is combined with an adaptive multichannel filter, which can exploit a fast recursive least squares (RLS) algorithm. The resulting approximation and the behavior of the system in the learning case is discussed. Simulations results are given for the linear prediction case, for which an additional adaptive procedure is derived. Sinusoidal signals are used at the input, since the inherent cascade structure directly yields the frequencies of the sinusoids from the section coefficients. The proposed method brings the efficiency of least-squares techniques, in terms of accuracy and convergence rate, to the adaptive filter in cascade form View full abstract»

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  • An adaptive implementation of the “one-shot” decorrelating detector for CDMA communications

    Publication Year: 1997 , Page(s): 762 - 765
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    Researchers have already shown, in principle, that an optimum detector for multiple users in a code-division multiple-access (CDMA) environment exists and that its performance is vastly superior to the single user detector in a multiuser environment. However, the complexity of this detector increases exponentially with the number of users. In this work, an adaptive algorithm and a possible implementation of the “one-shot” decorrelating detector is proposed. The algorithm generates a suboptimum “near-far” resistant despreading waveform for correlation with a known signal in a CDMA environment. In a K-user environment, only the waveforms and respective delays of all active users are required. The algorithm can be easily extended to as many users as desired using a simple recursive equation View full abstract»

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  • Forward and inverse scattering for discrete layered lossy and absorbing media

    Publication Year: 1997 , Page(s): 710 - 722
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    A complete digital signal processing (DSP) theory is developed for forward and inverse scattering in discrete (piecewise-constant) layered lossy systems, generalizing previous work for discrete lossless systems and continuous lossy systems. This paper is motivated by radar reflections from stratified dielectrics and interchip communication modeled by lossy transmission lines. The DSP formulation allows exact solutions, without discretization approximations, and includes all multiple reflections, transmission scattering losses, and absorption effects. For the forward problem, discrete matrix Green's functions are derived for the lossy medium, as are fast algorithms for computing impulse reflection and transmission responses for the medium. For the inverse problem, asymmetric Toeplitz systems of equations which function as discrete counterparts to integral equations are derived, as are fast algorithms for reconstructing the medium from its impulse transmission and reflection responses. Data sufficiency and feasibility are discussed. Finally, these results are applied to the LCRG transmission line and layered dielectric medium problems, dispersion effects are discussed, and a numerical example is presented View full abstract»

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  • Analytical two-dimensional IIR notch filter design using outer product expansion

    Publication Year: 1997 , Page(s): 765 - 768
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    This work is concerned with the two-dimensional (2-D) digital notch filter design problem. First, the outer product expansion is used to reduce the 2-D notch filter design problem to two pairs of one-dimensional (1-D) filter design problems. Then, we develop a simple algebraic method for the design of two pairs of 1-D IIR filters. This approach not only has closed form transfer function but also satisfies bounded input/output (BIBO) stability condition. Finally, one example is included to illustrate the proposed design method, and the 2-D IIR notch filter is applied to eliminate the sinusoidal interference superimposed on an image View full abstract»

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  • Auditory feature extraction using self-timed, continuous-time discrete-signal processing circuits

    Publication Year: 1997 , Page(s): 723 - 728
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    A compact integrated subsystem for accurate real-time measurement of level crossing time-intervals, suitable for multiresolution feature extraction from an analog cochlear filter bank is presented. The subsystem is inspired by the function of the inner hair cells in the mammalian cochlea and is based on continuous time discrete-signal processing circuits. Experimental results from a fabricated array of nine elements demonstrate instantaneous frequency-to-voltage conversion over a range covering the audio band. The power consumption is less than 20 μW per cell from a 5 V supply, when the system is biased to operate over the speech frequency range View full abstract»

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  • Design of recursive 1-D variable filters with guaranteed stability

    Publication Year: 1997 , Page(s): 689 - 695
    Cited by:  Papers (47)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    The digital filters with adjustable frequency-domain characteristics are called variable filters. Variable filters are used in many signal processing fields, but the recursive variable filters are extremely difficult to design due to the stability problem. This paper proposes a new method for designing recursive one-dimensional (1-D) variable filters whose stability is guaranteed. The method finds the coefficients of the transfer function of a variable digital filter as the multidimensional (M-D) polynomials of a few variables. The variables specify different frequency-domain characteristics, thus, we call the variables the spectral parameters. In applying the resulting variable filters, substituting different values of the spectral parameters into the M-D polynomials will obtain different filter coefficients and, thus, obtain different frequency-domain characteristics. To guarantee the stability, we first perform coefficient substitutions on the denominator coefficients such that they satisfy the stability conditions. Then both denominator and numerator coefficients are determined as M-D polynomials. In determining the M-D polynomials, we also propose an efficient least-squares approximation method that requires only solving simultaneous linear equations. Two examples are given to show the effectiveness of the proposed variable filter design technique View full abstract»

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  • A structured matrix approach for spatial-domain approximation of 2-D IIR filters

    Publication Year: 1997 , Page(s): 769 - 774
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    This work addresses least-squares (LS) approximation of a prescribed spatial response by a quarter-plane 2-D IIR filter. Using structured matrix representation it is shown that the spatial domain error vector between the desired and estimated responses is linearly related to the numerator coefficients and nonlinearly related to the denominator coefficients. The numerator and denominator estimation problems are theoretically decoupled without affecting the optimality properties. The decoupled denominator criterion possesses a quasi-quadratic form and its optimization is computationally efficient requiring very few iterations, The numerator is estimated linearly in a single step. Effectiveness of the algorithm is demonstrated with several examples View full abstract»

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  • Minimization of memory access overhead for multidimensional DSP applications via multilevel partitioning and scheduling

    Publication Year: 1997 , Page(s): 741 - 753
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    Massive uniform nested loops are broadly used in multidimensional digital signal processing (DSP) applications. Due to the large amount of data handled by such applications, the optimization of data accesses by fully utilizing the local memory and minimizing communication overhead is important in order to improve the overall system performance. Most of the traditional partition strategies do not consider the effect of data access on the computational performance. In this paper, a multilevel partitioning method, based on a static data scheduling technique known as carrot-hole data scheduling, is proposed to control the data traffic between different levels of memory. Based on this data schedule, optimal partition vector, scheduling vector and the partition size are chosen in such a way to minimize communication overhead. Nonhomogeneous size partitions are the final result of the partition scheme which produces a significant performance improvement. Experiments show that by using this technique, local memory misses are significantly reduced as compared to results obtained from traditional methods. This method can be used in application specific DSP system design and compiler for DSP processors View full abstract»

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  • Floating-point roundoff noises of first- and second-order sections in parallel form digital filters

    Publication Year: 1997 , Page(s): 774 - 779
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Assuming wide-sense stationary white noise input, we investigated the floating-point roundoff noises of first- and second order digital subfilters. For first-order subfilters, the roundoff noise of parallel form 3P realization is invariably smaller than that of the corresponding parallel form 1P realization. The floating-point roundoff noise of a second-order subfilter depends on the order of additions. Criteria are developed to find the best order and to make the choice between parallel form 1P and 3P realizations View full abstract»

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  • Optimum phase-acquisition technique for charge-pump PLL

    Publication Year: 1997 , Page(s): 729 - 740
    Cited by:  Papers (11)  |  Patents (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    In this paper, we propose a new optimum phase-acquisition algorithm controlling the loop gain of a charge-pump PLL (CP-PLL) in the sense of the MMSE criterion. A set of recursive difference equations minimizing RMS jitter of output phase is derived to obtain an optimum gear-shifting sequence with a zero-phase start (ZPS) assumption. It is shown that the optimum gear-shifting sequence is independent of the variance of the input phase jitter. A procedure for applying this sequence to the design of CP-PLL circuits is described, Both behavoral simulation and HSPICE circuit-level simulation demonstrate that the proposed design leads to an efficient CP-PLL having both fast acquisition and significant jitter reduction characteristics. The optimal gear-shifting CP-PLL outperforms the conventional CP-PLLs. These methods can be used for clock recovery applications such as data communication receivers, disk drive read/write channels, and local area networks, as well as for other applications requiring very short initial preamble periods View full abstract»

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  • Pointer adaptation and pruning of min-max fuzzy inference and estimation

    Publication Year: 1997 , Page(s): 696 - 709
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    A new technique for adaptation of fuzzy membership functions in a fuzzy inference system is proposed. The pointer technique relies upon the isolation of the specific membership functions that contributed to the final decision, followed by the updating of these functions' parameters using steepest descent. The error measure used is thus backpropagated from output to input, through the min and max operators used during the inference stage. This occurs because the operations of min and max are continuous differentiable functions and, therefore, can be placed in a chain of partial derivatives for steepest descent backpropagation adaptation. Interestingly, the partials of min and max act as “pointers” with the result that only the function that gave rise to the min or max is adapted; the others are not. To illustrate, let α=max [β1, β2, ···, βN]. Then ∂α/∂βn=1 when βn is the maximum and is otherwise zero. We apply this property to the fine tuning of membership functions of fuzzy min-max decision processes and illustrate with an estimation example. The adaptation process can reveal the need for reducing the number of membership functions. Under the assumption that the inference surface is in some sense smooth, the process of adaptation can reveal overdetermination of the fuzzy system in two ways. First, if two membership functions come sufficiently close to each other, they can be fused into a single membership function. Second, if a membership function becomes too narrow, it can be deleted. In both cases, the number of fuzzy IF-THEN rules is reduced. In certain cases, the overall performance of the fuzzy system can be improved by this adaptive pruning View full abstract»

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  • An automatic gain control architecture for SONET OC-3 VLSI

    Publication Year: 1997 , Page(s): 779 - 783
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    This work presents a synchronized feedback-type automatic gain control (AGC) architecture for SONET (synchronous optical network) OC-3 system which is suitable for scaled BJT or CMOS VLSI implementation. In this architecture, a second-order loop is utilized instead of a conventional loop, and a convenient methodology is presented for calculating the parameters of the AGC. Simulation results using micromodels in the HSPICE environment indicate that for a 20 dB dynamic range of input 77.76 MHz sinusoidal signal, the architecture yields an 80 kHz loop bandwidth and a constant 1 Vpp output magnitude View full abstract»

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  • A new IIR algorithm based on the overlap-save approach

    Publication Year: 1997 , Page(s): 783 - 785
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (96 KB)  

    In this work, a new IIR algorithm is presented. It is based on a block implementation method for IIR filters, and has two stages. First, a circular convolution is used to transform the input into intermediate results. Second, a correction circuit transforms the intermediate result into the correct output. Because the correction circuit uses part of the previous output to correct the current intermediate result, our approach is an overlap-save based algorithm. The multiplicative complexity of this algorithm is shown to be 2 log (kn)+[8 log(n)+12/k]+1 real multiplications per output point, for a block of size kn, where n is the order of the filter and k⩾2, is a constant. This complexity is much less (by more than 50%) than other known algorithms. Another advantage of this algorithm is that it is easily parallelizable View full abstract»

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  • Eigen design of quadrature mirror filters

    Publication Year: 1997 , Page(s): 754 - 757
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    This work presents a method for the design of quadrature mirror filters. A new frequency weighted stopband energy function is introduced, which leads to considerable flexibility in the design process. Unlike other techniques which involve searches and nonlinear optimization, our formulation reduces the design equations to an eigenvector problem. Furthermore, the resulting filters are regular and have additional desirable properties for applications to pyramidal coding of images, which together with DPCM, PCM, vector quantization, or zero-tree wavelet coding schemes leads to high compression ratios View full abstract»

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Aims & Scope

This title ceased production in 2003. The current updated title is IEEE Transactions on Circuits and Systems II: Express Briefs.

Full Aims & Scope