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Author

Joe F. Chicharo

Bio: Joe F. Chicharo is an academic researcher from University of Wollongong. The author has contributed to research in topics: Adaptive filter & Blind signal separation. The author has an hindex of 24, co-authored 139 publications receiving 2382 citations. Previous affiliations of Joe F. Chicharo include Zhengzhou University & University of Oldenburg.


Papers
More filters
Journal ArticleDOI
TL;DR: A sliding Goertzel algorithm to accurately estimate the Fourier coefficients of multifrequency (MF) sinusoidal signals buried in noise is presented, based on second-order digital resonators that are tuned at the desired frequencies.

312 citations

Journal ArticleDOI
TL;DR: The use of gradient-based algorithms with infinite impulse response (IIR) notch filtering for estimating sinusoids imbedded in noise is investigated and error surface analysis indicates that second-order modules are unimodal and result in guaranteed convergence.
Abstract: The use of gradient-based algorithms with infinite impulse response (IIR) notch filtering for estimating sinusoids imbedded in noise is investigated. Two notch filter model structures are presented. The first is for applications where two signal sources with correlated noise components can be assessed. The second can be used in situations where only one composite signal source is available. Error surface analysis indicates that second-order modules are unimodal and result in guaranteed convergence. Higher-order modules are multimodal and require judicious choice of initial parameter estimates. Simulation results are included to demonstrate the performance characteristics of both filter structures. >

154 citations

Journal ArticleDOI
TL;DR: Combining the new algorithms for estimating the laser phase and updating C value, the paper finally presents a novel technique for displacement measurement with improved accuracy performance in contrast to existing techniques.
Abstract: Approaches that are, to our knowledge, novel, are proposed in this paper to improve the accuracy performance of self-mixing interferometry (SMI) for displacement measurement First, the characteristics associated with signals observed in SMI systems are studied, based on which a new procedure is proposed for achieving accurate estimation of the laser phase The studies also revealed the reasons for the inherent errors associated with the existing SMI-based techniques for displacement measurement Then, this paper presents a new method for estimating the optical feedback level factor (denoted by C) in real time Combining the new algorithms for estimating the laser phase and updating C value, the paper finally presents a novel technique for displacement measurement with improved accuracy performance in contrast to existing techniques The proposed technique is verified by both simulation and experimental data

121 citations

Proceedings ArticleDOI
18 Jun 2000
TL;DR: This work addresses issues with the performance of IEEE 802.11, when used in the adhoc mode, in the presence of hidden terminals, and presents results illustrating the strong dependence of channel capture behavior on the SNR observed on contending hidden connections.
Abstract: We address issues with the performance of IEEE 802.11, when used in the adhoc mode, in the presence of hidden terminals. We present results illustrating the strong dependence of channel capture behavior on the SNR observed on contending hidden connections. Experimental work has illustrated that in a hidden terminal scenario, the connection having the strongest SNR is able to capture the channel, despite the use of the RTS-CTS-DATA-ACK 4-way handshake designed to alleviate this problem. Our results indicate that the near-far SNR problem may have a significant effect on the performance of an adhoc 802.11 network.

105 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new approach which attempts to remedy the underlying problem by modifying the actual sampled sequence such that it becomes an ideal sample sequence which is synchronized with the signal subjected to sampling.
Abstract: Digital periodic signal analysis often requires synchronized sampling with the signal being analyzed. In certain practical situations, however, this condition is difficult to satisfy. As a result, a number of undesirable effect such as the spectral leakage associated with the discrete Fourier transform (DFT), and the truncation errors in digital wattmeters arise and degrade system performance. This paper presents a new approach which attempts to remedy the underlying problem. The basic idea of the proposed method is to modify the actual sampled sequence such that it becomes an ideal sample sequence which is synchronized with the signal subjected to sampling. A simple algorithm for modifying the sampled sequence on-line is derived based on interpolation. The proposed approach requires quite modest additional computational burden which makes it suitable for real-time signal professing. To illustrate the practical applicability of the proposed algorithm, the paper considers two distinct but common cases. First, it shows how the proposed method can be used in the case of DFT analysis of harmonic signals, and secondly, it considers the digital wattmeter application area in electrical power-system measurement. Results show that the proposed algorithm is capable of reducing both the leakage effect in DFT analysis and truncation errors in digital wattmeters.

82 citations


Cited by
More filters
Journal Article
TL;DR: In this article, a fast Fourier transform method of topography and interferometry is proposed to discriminate between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour generation techniques.
Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

3,742 citations

Journal ArticleDOI
01 Oct 1980

1,565 citations

Journal ArticleDOI
TL;DR: Computer and Robot Vision Vol.
Abstract: Computer and Robot Vision Vol. 1, by R.M. Haralick and Linda G. Shapiro, Addison-Wesley, 1992, ISBN 0-201-10887-1.

1,426 citations

Patent
10 Feb 1998
TL;DR: In this article, an electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated.
Abstract: An electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated. The advantage of the power control system is that thermal spread and charring are reduced. In addition, the power control system offers improved performance for electrosurgical vessel sealing and tissue welding. The output power is applied cyclically by a control system with tissue impedance feedback. The impedance of the tissue follows the cyclic pattern of the output power several times, depending on the state of the tissue, until the tissue becomes fully desiccated. High power is applied to cause the tissue to reach a high impedance, and then the power is reduced to allow the impedance to fall. Thermal energy is allowed to dissipate during the low power cycle. The control system is adaptive to tissue in the sense that output power is modulated in response to the impedance of the tissue.

1,164 citations