Gabor Peceli

• Professor
• Professor (Full) at Budapest University of Technology and Economics

Recently, an observer-based algorithm was reviewed that is able to perform recursive sliding discrete Fourier transform (SDFT) [1]. DFT is the basic algorithm used for Fourier analysis [2], but it provides unbiased estimates only if the sampling is coherent, i.e., the ratio of the sampling frequency f <sub xmlns:mml="http://www.w3.org/1998/Math/Mat...

Matched filtering is a well-known method frequently used in digital signal processing to detect the presence of a pattern in a signal. In this paper, we suggest a time variant matched filter, which, unlike a regular matched filter, maintains a given alignment between the input signal and the template carrying the pattern, and can be realized recurs...

Filter Bank Multicarrier (FBMC) systems are a class of multicarrier modulation schemes for high speed wireless communication. These systems are known for their low adjacent channel leakage. In this paper we focus on the problem of channel equalization for FBMC systems. Most solutions in the literature use a per subcarrier equalization suffering fro...

This paper introduces a new, adaptive-filter-based controller that shows advantageous properties from the viewpoint of its communication requirement. The algorithm is called signed-error filtered-x LMS (SE-FxLMS). Its novelty is characterized by the fact that it makes possible data compression in the feedback path of adaptive-filter-based control l...

This paper deals with the synchronization in wireless adaptive signal processing systems. Wireless communication offers high flexibility, however, the distributed structure of wireless systems requires the synchronization of the subsystems. The synchronization becomes particularly important if the signal bandwidth is in the kHz range, and it is ine...

Run-time reconfiguration of digital signal processing systems is common in today's complex, non-linear and/or time-variant, distributed signal processing and control solutions. Reconfiguration transients caused by the run-time configuration change degrade the quality of service provided by solution, and they may also cause failures in the system. T...

Spectral observer is appropriate for investigating the frequency domain properties of signals. Since the spectral analysis is a very common method, this observer can be used widely in many applications. The paper introduces a novel resonator based spectral observer and control algorithm that require reduced amount of data for the operation, so they...

This paper investigates the problem of spectral observation in case of unevenly sampled input data. In [1] Hostetter proposed a dead-beat observer structure and an algorithm to calculate the observer gain values online. In this paper we give a formal proof of correctness of this algorithm and we also propose an efficient numerical method to reduce...

Due to the several attractive features of wireless devices they are more and more expansively used, but the deployment of wireless sensors in control applications is not spread yet because of the unreliable data transfer. This paper introduces a testbed which serves as a platform for investigations of wireless closed loop adaptive signal processing...

A nonparametric identification method for linear systems is proposed. The identification is done via synchronized multisine measurements where the synchronization is ensured by a resonator-based generator-observer pair. The advantage of the proposed structure is that it works as a filter bank and, hence, provides the measurement results online. Exp...

IntroductionFACT ArchitectureModeling Hybrid Systems and ControllersThe Hybrid ObserverApproaches to Fault Detection and IsolationController SelectionConclusion and Future WorkReferences

Complex control applications require capabilities for accommodating faults in the controlled plant. Fault accommodation involves the detection and isolation of faults, and then taking appropriate control actions to mitigate the fault effects and maintain control. This requires the integration of fault diagnostics with control in a feedback loop. Th...

Reconfigurable digital filters are promising solutions to filtering problems in hybrid systems, where digital filters with time-invariant configuration are found to be inappropriate. However, reconfiguration of digital filters causes intermediate disturbances, reconfiguration transients that have to be minimized by proper transient management. In t...

We present a block library for Matlab/Simulink that allows fast prototyping of reconfigurable DSP systems. Up till now no similar software package was available. The block library supports the construction of reconfigurable discrete time linear and nonlinear systems from reconfigurable digital filters using various filter structures, state-space fo...

In distributed signal processing systems, every node samples analog signals by its own AD converter. Sampling is controlled by autonomous clocks, that are generally not synchronizable. In order to ensure synchronized operation among the different nodes of the distributed system, both the drift of these clocks, and the jitter of the sampling is hand...

Most embedded signal processing applications are developed in at least two separate stages: signal-processing design followed by its digital implementation. With such an approach computational tasks that implement the signal processing algorithms are usually scheduled by treating their execution times and periods as unchangeable parameters. Task sc...

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Self-adaptive software is a technology that allows building fault-adaptive control systems: control software that can survive faults in the system under control, and in the control software itself. This form of self-adaptive software requires capabilities for the detection and isolation of faults when the system is in operation, and then taking app...

A user interface is considered invariant, if its operation is built around a set of predefined fix points of using information systems. We argue that in interfaces of complex software applications such fix points are increasingly necessary, however they have been given far too few attention in the past. Some potential benefits of invariant user int...

Self-adaptive software systems use observations of their own behavior, and that of their environment, to select and enact adaptations in accordance with some objective(s). This adaptation is a higher-level system function that performs optimizations, manages faults, or otherwise supports achieving an objective via changes in the running system. In...

This report investigates the transient phenomena due to run-time reconfigurations in controlled systems. It is shown that in the case of dynamic systems these reconfiguration transients might be reduced to a considerable extent using dedicated design-time and/or run-time methods. The methodology behind applies the so-called model-integrated approac...

Fault adaptive systems must adapt and reconfigure themselves to the changes in the environment or the system itself, and have to maintain operation even in case of system failures. In order to avoid performance degradation due to system reconfigurations, adequate reconfiguration management is necessary. This paper describes a fault-adaptive control...

Complex control applications require a capability for accommodating faults in the controlled plant. Fault accommodation involves the detection and isolation of faults, and taking an appropriate control action that mitigates the effect of the faults and maintains control. This requires the integration of fault diagnostics with control, in a feedback...

Self-adaptive software systems use observations of their own behavior, and that of their environment, to select and enact adaptations in accordance with some objective(s). This adaptation is a higher-level system function that performs optimizations, manages faults, or otherwise supports achieving an objective via changes in the running system. In...

System reconfiguration at run time may cause unacceptable transients. In this paper, a new design methodology is proposed for reducing transients due to reconfiguration in recursive digital signal processing (DSP) systems. The technique utilizes the fact that, 1) transfer functions can be realized by different processing structures, and 2) these al...

A nonparametric identification method for linear systems is proposed. The identification is done via synchronized multisine measurements where the synchronization is ensured by a resonator based generator-observer pair. The advantage of the proposed structure is that it works as a filter bank and provides the measurement results on-line. Exponentia...

Complex control applications require a capability for accommodating faults in the controlled plant. Fault accommodation involves the detection and isolation of faults, and taking an appropriate control action that mitigates the effect of the faults and maintains control. This requires the integration of fault diagnostics with control, in a feedback...

Reconfigurable control systems are promising alternatives to efficiently control complex time-variant and/or non-linear systems, such as vehicles, gas turbines, etc., which might require a certain level of fault-operational behaviour, as well. Reconfigurable control systems are designed to be able to change the controller at run-time to react to fa...

In control systems undesirable transients may occur when either the controller or the plant is reconfigured during the operation. This paper gives a new solution for the transient reduction problem in simple feedback control loops to maintain the smooth steady-state behavior even if both the plant and the controller are changed simultaneously. The...

System reconfiguration at run time may cause unacceptable transients. In this paper a new design methodology is proposed for reducing transients due to reconfiguration in recursive digital signal processing (DSP) systems. The technique utilizes the fact that, (1) transfer functions can be realized by different processing structures, and (2) these a...

In this paper transient management techniques are investigated in a scenario where the reconfiguration or replacement of a forward-loop controller is required due to changes in the environment or in the plant. Such a change in the closed control loop may have undesirable transient effects, which may degrade the performance of the controlled system....

Self-adaptive systems reconfigure themselves to improve their operation when changes in the environment imply to do so. Reconfiguration usually means the replacement or modification of some functional components so that the new components provide better performance, more robust operation, or better functionality. Such a reconfiguration, however, ma...

To solve measurement and control problems, the processing of input data is performed typically by model-based digital signal processing (DSP) systems, which contain a representation of our knowledge about the nature and the actual circumstances of the problem at hand. If the nature or the actual circumstances change, the corresponding model should...

A PLL-like adaptive Fourier analyzer (AFA) was proposed which has shown excellent performance in practical applications. The convergence analysis of this AFA is extremely difficult, and until now theoretical results have not been available. In this paper a modified version of the original AFA is proposed. The new version preserves the effectiveness...

Nowadays in solving measurement and control problems the processing of input data is performed typically by model-based digital signal processing (DSP) systems which contain a representation of our knowledge about the nature and the actual circumstances of the problem in hand. If the nature and/or the actual circumstances change the corresponding m...

Nowadays model based techniques play very important role in solving measurement and control problems. Recently for representing nonlinear systems fuzzy models became very popular. For evaluating measurement data and for controller design also the inverse models are of considerable interest. In this paper a technique to perform fuzzy model inversion...

Measurements of any kind are characterized on one hand by their uncertainty due to modeling and measurement errors. Unfortunately for several reasons this characterization is not easy and requires further (human and/or machine based) considerations and intensive computing. As an alternative measurements are characterized also by their accuracy whic...

Block-oriented signal processing techniques have an exceptional role due to the availability of fast algorithms. However, if larger data segments are to be evaluated in real-time, the delay caused by the block-oriented approach is not always tolerable especially if the response time of the evaluating system is also specified. This can be exceptiona...

Active cancellation of acoustic noise seems to be a real alternative to passive isolation in the low frequency region. There are already many methods to solve this control problem, typically based on adaptive filter techniques. If the noise is periodic, a simple signal model can be integrated into the adaptive controller, the parameters of which ar...

The classical “frequency sampling method” (1975) based on the direct utilization of the Lagrange interpolation technique is extended in a natural way to a rather efficient Hermite interpolation scheme. This structure is a new extension related to the resonator-based digital filter family introduced by M. Padmanabhan et al. (1996). The development r...

The authors have developed a new method for periodic acoustic noise cancellation which is already proved to work efficiently in the practice. A simulation had preceded the implementation, in order to have experiments with different types of acoustic systems. The simulations were carried out in MATLAB which is widely used for such investigations. Th...

In the previous chapters, we discussed the theory and application of various signal processing blocks that fall in the framework of an observer. In this chapter, we will consider hardware implementations of some of these signal-processing blocks.

In this chapter, we will apply the observer-based perspective to the problem of digital filtering and design a filter structure that has good properties under finite precision conditions. As of date, there are several digital filter structures that provide good behavior under these conditions [Pec89, PM93, MR76, Fet86, GM75, DD80, DvdV19, RK84, VM8...

In this chapter, we primarily examine the problem of computing an N * N transform on an input vector, in a time-recursive manner, and show how the feedback-based structure may be used for this application. The N * N transforms, in general, provide alternative signal representations which may be helpful in solving signal characterization problems, o...

In this chapter, we consider the problem of spectral estimation and line enhancement. To simplify matters, we will assume throughout the chapter that the input is a multi-sinusoidal signal; such a signal could be produced by a hypothetical system comprising of a parallel bank of resonators, and our objective is not only to estimate the frequencies...

Due to their simplicity and small computational complexity gradient-type algorithms play an important role in the field of adaptive filtering and system identification. In practical cases, however, these algorithms often fail to converge to the global minimum when the error surface is multimodal. There are algorithms - known and to be presented her...

Insufficient-order system identification can result in a multimodal mean square error surface on which a gradient-type algorithm may converge to a local minimum. In this letter a new composite gradient algorithm (CGA) is presented which is due to achieve global convergence when the output error surface contains local minima. The proposed algorithm...

Due to their simplicity and small computational complexity gradient-type algorithms play an important role in the field of adaptive filtering and system identification. In practical cases, however, these algorithms often fail to converge to the global minimum when the error surface is multimodal. There are algorithms - known and to be presented her...

The applicability of the recursive Walsh-Hadamard transformation to FIR and IIR (finite- and infinite-impulse-response) filtering is investigated. It is shown that using a common structure for recursive transforms recently introduced by G. Peceli (1986), the usual frequency-domain FIR filtering problem can be easily converted into a Walsh sequency-...

A digital filter structure that is structurally passive and can suppress all zero-input limit cycles, and if rounding is applied provides minimum roundoff noise is presented. These properties are due to the fact that this structure generates its output as a linear combination of orthogonal signal components, thus internally implementing an orthogon...

This contribution reports on the endeavours and practical experiences in teaching AI techniques at the Faculty of Electrical Engineering of the Technical University of Budapest. Teaching AI techniques means on one hand an introduction to knowledge-based information processing, expert systems, and expert systems tools, while on the other the introdu...

The sensitivity properties of the recently introduced common structure for recursive discrete transforms are investigated. This structure is based on digital resonators in a feedback loop. It is shown that this structure has very nice sensitivity properties near to the resonator pole frequencies, and that by locating the resonator poles properly, e...

An implementation of FIR (finite impulse response) and IIR (infinite impulse response) filter transfer functions is presented that is structurally passive and hence has very low passband sensitivity. This implementation is based on G. Peceli's (1986) common structure for recursive discrete transforms. This structure consists of digital resonators i...

The authors introduce system design methods that can contribute to the resolution of the rather complex requirements in the field of medical instrumentation, drawing on their own experiences in the development of intelligence EEG recorders and analyzers. They focus on the integration of the knowledge base with the numerical database and the algorit...

This paper presents a common framework for the recursive implementation of arbitrary discrete transformations. The transform coefficients to be applied are periodically time-varying and can be derived from the discrete basis functions of the transforms. The method is based on Hostetter's dead-beat observer approach to signal processing [1], [2], bu...

The authors describe a multi-purpose arrangement enabling the recursive realization of any discrete transformation. Explicit expressions are given for the parameters and there is also a reference to the design of finite and infinite (FIR and IIR) impulse response filters using recursive transformations.

Observer theory is well known from the literature of control technology - the article shows its applicability to signal processing. It deals briefly with fundamental properties of the observers, then with the observer-based recursive derivation of various transformation procedures. Explicit relations are given for recursive transformations with obs...

This paper introduces some practical issues of the deployment of wireless sensor networks (WSNs) in closed loop digital signal processing (DSP) and control systems that require relatively fast, continuous data flow and real-time operation of the data collecting network, as in the case of traditional systems where sensors are attached by wire. The d...

This paper presents a technique for representing distributed data of sensor networks. The approach is based on a general distributed regression framework that models sensor data by fitting a global function to each of the local measurements. The presented method explores the possible extensions of this distributed regression, by using more complex...

This paper presents the design considerations of a modular hardware-software platform devoted to serve education, research and development in the fields of ambient intelligence, ubiquitous/pervasive computing, and networked embedded systems. The primary goal of this new platform is to support Embed-ded Information Systems Engineering education at t...