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

Issue 8 • Date Aug 1993

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Displaying Results 1 - 10 of 10
  • Matrix two-dimensional spectral factorization

    Page(s): 509 - 511
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    The existence of an asymmetric half-plane spectral factorization for a nonnegative two-dimensional matrix-valued spectral density is established under the conditions that the density and the logarithm of the determinant of the density are absolutely integrable on the torus. The proof gives a construction of the factors in terms of a family of one-dimensional spectral factorizations. An efficient algorithm for calculating the two-dimensional spectral factorization is thereby obtained; G.T. Wilson's (1972) one-dimensional factorization algorithm appears to be the most suitable for this purpose. In the case where the initial array is of finite extent, it is shown that the factors have constant (minimal) order in the `causal' direction, and that, if a finite-support array has a quarter-plane spectral factorization, the spectral factors must also be of finite support View full abstract»

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  • Feedback-based orthogonal digital filters

    Page(s): 512 - 525
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    A synthesis procedure for generating orthogonal structures to implement arbitrary transfer functions is described. As compared to earlier techniques associated with orthogonal filter synthesis, which used a cascade of sections or a parallel combination of sections, this method uses feedback to simplify the design process, and results in filter structures that have the low-passband-sensitivity properties associated with orthogonal structures. Additionally, the structure is inherently L2-scaled; thus, the design process is simplified because an additional scaling step is not necessary. One of the other advantages of the new structure is that its stability monitoring is very easy; thus, it is extremely well suited for adaptive applications. The method is motivated by some recently reported resonator-based digital-filter structures View full abstract»

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  • Limit cycle bounds for floating point implementations of second-order recursive digital filters

    Page(s): 493 - 501
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    It is shown that floating point realizations of linearly stable systems can exhibit four fundamental types of free responses. Sufficient conditions for the existence or nonexistence of some of these periodic response types in a given system are presented. Explicit closed form conditions on the mantissa length to guarantee certain limit cycle bounds are provided. The effect of various floating point arithmetic reformatting schemes on the convergence of recursive difference equations is also addressed. Truncation and rounding quantization schemes as well as double- and single-length product mantissa schemes are analyzed and compared. Although the method introduced is applicable to any digital filter realization implemented in floating point format, the analysis focuses on the zero-input behavior of second-order direct-form digital filters View full abstract»

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  • Fast discrete extrapolation via the fast Hartley transform

    Page(s): 502 - 504
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    A fast algorithm for A. Papoulis's (1975) and R.W. Gerchberg's (1974) iterative extrapolation based on the fast Hartley transform (FHT) is presented. The low-pass filtering in the iterative procedure can be implemented by the FHT directly instead of by the fast Fourier transform (FFT) and the inverse FFT. M.S. Sabri and W. Steenart's (1978) example demonstrates that the FHT approach is simple to use View full abstract»

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  • Arithmetic for ternary number-theoretic transforms

    Page(s): 529 - 531
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    A simplified arithmetic for the computation of ternary number-theoretic transforms is presented. The proposed arithmetic is based on the application of a code translation technique that was used by L.M. Leibowitz (1976) for the development of a simplified binary arithmetic for the computation of the Fermat number-theoretic transform View full abstract»

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  • Image sequence enhancement based on adaptive symmetric order statistics

    Page(s): 504 - 509
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    Statistical properties of the spatiotemporal center-weighted median (CWM) filter for image sequences are investigated. It is statistically shown that the CWM filter preserves image structures under motion at the expense of noise suppression. To improve the CWM filter so it can be effectively used in image sequence processing, the adaptive directional CWM filter (ADCWM) is proposed. This filter utilizes a multistage filtering structure, based on adaptive symmetric order statistic (ASOS) operators which produce a pair of order statistics symmetric about the median. The ASOSs are selected by using adaptive parameters adjusted by local image statistics. It is shown experimentally that the proposed filter can preserve image structures while attenuating noise without the use of motion estimation View full abstract»

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  • Adaptive IIR notch filter based on least mean p-power error criterion

    Page(s): 525 - 528
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    A new second-order IIR adaptive notch filter (ANF) algorithm based on least-mean-p-power (LMP) error criterion is investigated. When the ANF is used to cancel 60-Hz interference in the recording of electrocardiograms (ECG), the performance of this adaptive algorithm with p=1 is better than that of the conventional least-mean-square (LMS, p=2) algorithm. Furthermore, when the ANF is applied to estimate the frequency of sinusoid embedded in white noise, this algorithm with p=3 has better statistical accuracy than the LMS algorithm. Simulation results are presented to demonstrate the effectiveness of the proposed ANF algorithm View full abstract»

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  • Digital characterization techniques for the analog performance of mixed-signal devices

    Page(s): 480 - 492
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    The authors describe a theoretical framework for obtaining a detailed characterization of the analog properties of a mixed-signal transmission channel and present experimental results for the technique applied to an actual device. The inputs to, and outputs from, the channel under test are all digital. They thus avoid the many problems associated with analog fixturing and wiring and obviate the need for analog instrumentation. These experiments show that extensive performance information can be obtained with high accuracy and repeatability if the proper type of digital signal processing is employed. The characterization and testing issues described are generic to many newer analog and mixed-signal devices View full abstract»

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  • An empirical study of high-order single-bit delta-sigma modulators

    Page(s): 461 - 466
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    Computer simulations are used to determine the stability limits of single-bit delta-sigma modulators up to order 8. It is found that none of the existing criteria for stability are adequate for design. Plots of the maximum signal-to-noise ratio (SNR) achievable with a given modulator order and oversampling ratio (OSR) are presented. These graphs can be used to determine the modulator order and OSR required to achieve a given SNR or to check the tightness of (as yet unavailable) theoretical bounds View full abstract»

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  • On the behavior of the double-loop sigma-delta modulator

    Page(s): 467 - 479
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    The authors prove a stability theorem for the integrator states of the double-loop sigma-delta modulator with inputs chosen from a class of functions that satisfy certain boundedness conditions. This input class includes functions formed from the sum of a limited magnitude constant term and a finite sum of sinusoids of arbitrary amplitude and of nonzero frequency. To demonstrate the quality of the state bounds derived in the stability theorem, they construct external periodic solutions for the modulator equations with pure sinusoidal inputs. Some observations on the case of constant (DC) inputs are also presented. It is shown that for rational DC inputs and for rational initial states, the output of the double-loop modulator becomes periodic in a finite number of iterations. The length of this period is dependent on the DC value and on the initial conditions of the modulator 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