J. Szczupak

An approach to the implementation of digital filters using microprocessors

The design of digital filters using microprocessors is discussed along with simple solutions to improve the speed and memory requirements of such systems.

On digital filter structures with low coefficient sensitivities

A simple network transformation method is proposed to generate equivalent digital filter structures whose multiplier coefficients are functions of the parameters of the transformation. An application of this proposed approach, illustrated here, is in generating structures with low coefficient sensitivities.

Adaptive sinusoid detection using IIR notch filters and multirate techniques

A structure for the detection of sinusoids using adaptive infinite impulse response (IIR) notch filters and multirate techniques is presented. By using the frequency enhancement property of the decimation in time process the structure avoids the use of almost unity radius notch filters. Computer simulations are used to demonstrate the performance of this method for the detection of closely spaced sinusoids and tracking of nonstationary signals. The method seems to be particularly useful for real-time and low-cost applications.<<ETX>>

A computer-based synthesis method of structurally LBR digital allpass networks

A digital lossless bounded-real (LBR) transfer function, more commonly known as a stable allpass function, maintains the LBR property under multiplier coefficient quantization when implemented by networks that are structurally LBR. A systematic method is outlined for generating all possible such realizations for second-order transfer functions containing a minimum number of multipliers and delays, allowing the designer to take advantage of the flexibility offered by a catalog of such realizations. Illustrative examples are included. >

An alternate parallel realization of digital transfer function

A new type of parallel realization of a digital transfer function is proposed. The new structure is also canonic with respect to delays, multipliers, and adders. Expressions for the round-off noise variances for the new structure and its transpose are derived. An illustrative example is included.

Minimization of coefficient sensitivities of digital filter structures

A computer-aided optimization procedure is used to illustrate the possibility of minimizing multiplier coefficient sensitivities of digital filter structures generated via network transformation approach. To this end, the parameters of the transformation are iteratively adjusted to minimize a new more appropriate sensitivity measure.

Building the Optimal Contract Portfolio under Non-Probabilistic Uncertainties

This paper proposes an integrated solution to the optimum portfolio building considering price and demand uncertainties. More than simply assessing risks, the proposed approach opens the possibility of a real and effective risk management, including maximum risk levels as optimization constraints. The resulting model corresponds to a stochastic non-linear integer programming problem and is solved by a customized algorithm, designed for efficiency and reliability. Possible extensions (targeting special markets customization) are straightforward and may be easily taken into account.

On the elimination of zero-input limit cycles digital filters)

Sufficient conditions for avoiding zero-input limit cycles are derived by considering generic structures. The method is based on a fixed-point finite precision arithmetic nonlinear network modeled as a linear time-varying network, allowing the extension of time-invariant conditions. Second order delay and multiplier canonic structures that satisfy the conditions are investigated. An illustrative case is included.<<ETX>>

Power system simulation using digital filter structures

The simulation of power systems for protection applications is developed based on digital filtering techniques. Although transmission lines are easily modeled by digital filters, lumped elements suffer severely in this process, resulting in large distortions or high sampling rates. Furthermore, the interconnection of digital filter models is usually noncausal due to the presence of delay-free-loops in the structure. This work deals with the causality problem and with the modeling of lumped networks. Two approaches are suggested for this modeling, the first involving approximation techniques and the second based on a multirate interpretation of the bilinear transform. Comparative examples are included.<<ETX>>

Tail window adaptation algorithm of IIR digital filters

The tail window adaptation algorithm is introduced as an extension of the general algorithm and applied to IIR (infinite impulse response) digital filter structures. It incorporates an extra design variable, related to the state memory length, the overall increase in computational complexity being determined as a function of the window width. The algorithm is applied to direct and parallel structures, indicating improvements in convergence speed and robustness. Nonstationary simulations are included.<<ETX>>