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1
Content available Comparison of acoustic, electric and laser contactless displacement measurements applied to observe nonlinear behaviour of diaphragm movement in dynamic loudspeakers
Kmiecik Michał, Pluta Marek J.
Vibrations in Physical Systems
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2023
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Vol. 34, nr 2
art. no. 2023203
EN
Dynamic loudspeakers introduce distortion into reproduced auditory signal, especially in case of operation with high power or low frequency. Assessment of distortion by measuring current of voice coil should allow to compensate or prevent the product of distortion. The paper contains a comparison of displacement capture by optical triangulation displacement sensor, acoustic signal acquired using microphone, voltage and current. In case of processing low frequency signals, acoustic signal captured by microphone is dominated by harmonics of the fundamental frequency, and the laser displacement sensor provides more accurate information about the diaphragm displacement. Harmonics recorded in current have the same character as the displacement signal for low frequency, but for frequencies above the resonance, acoustic signal is a better source of displacement information.
2
Elektromechaniczne sprzężenie zwrotne dla niskotonowych głośników dynamicznych z kaskadowym połączeniem dwóch regulatorów PID
Łysek Tomasz
Elektronika : konstrukcje, technologie, zastosowania
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2022
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Vol. 63, Nr 10
24--32
PL
Artykuł zawiera projekt nowej metody redukcji zniekształceń nieliniowych w torze sygnałowym. Publikacja prezentuje opis elektronicznego systemu służącego do redukcji zniekształceń nieliniowych w niskotonowych głośnikach dynamicznych, schemat blokowy oraz schemat ideowy zmodyfikowanego systemu elektromechanicznego sprzężenia zwrotnego a także wyniki pomiarów zniekształceń nieliniowych. Projekt ten stanowi nowe podejście do projektowania tego typu układów. Układ wykorzystuje kaskadowe połączenie dwóch regulatorów PID. Układ podrzędny realizuje sprzężenie prądowe natomiast układ nadrzędny realizuje sprzężenie przyspieszeniowe. Prezentowany układ elektroniczny pozwala na znaczącą redukcję zniekształceń nieliniowych w zakresie najniższych częstotliwości pasma akustycznego. Wyniki pomiarów potwierdzają prawidłowe działanie metody redukcji zniekształceń zaproponowanej w tej publikacji.
EN
This article includes the development of a new method of reducing nonlinear distortion in the signal path. The paper presents the description of the electronic system used to reduce the nonlinear distortion in low-frequency dynamic loudspeakers, the block diagram and the schematic diagram of the modified motional feedback system and the measurement results of non-linear distortion. This project is a new approach to the design of this type of circuit. The system uses a cascade connection of two PID-controllers. The slave controller implements the current feedback, while the master controller implements the acceleration feedback. The presented electronic circuit allows for a significant reduction of nonlinear distortion at the lowest frequencies of the acoustic band. The measurement results confirmed the correctness of the nonlinear distortion reduction method proposed in this publication.
3
Content available Operator o and analysis of harmonic distortion
Borys A.
International Journal of Electronics and Telecommunications
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2016
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Vol. 62, No. 3
261--265
EN
It has been shown that the description of mildly nonlinear circuits with the use of an operator o introduced by Meyer and Stephens in their paper published more than forty years ago was flawed. The problem now with their incorrect and imprecise definition is that it is still replicated in one or another form, as, for example, in publications of Palumbo and Pennisi on harmonic distortion calculation in integrated CMOS amplifiers or an article of Shrimali and Chatterjee on nonlinear distortion analysis of a three-terminal MOS-based parametric amplifier. Here, we discuss the versions of o operator presented in the works mentioned above and show points, where mistakes were committed. Also, we derive the correct forms of nonlinear circuit descriptions that should be used.
4
Content available On Modelling AM/AM and AM/PM Conversions via Volterra Series
Borys A., Sieńko W.
International Journal of Electronics and Telecommunications
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2016
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Vol. 62, No. 3
267--272
EN
In this paper, we present the expressions, not published up to now, that describe the AM/AM and AM/PM conversions of communication power amplifiers (PAs) via the Volterra series based nonlinear transfer functions. Furthermore, we present a necessary and sufficient condition of occurrence of the nonzero values of AM/PM conversion in PAs. Moreover, it has been shown that Saleh’s approach and related ones, which foresee nonzero level of AM/PM conversion, are not models without memory. It has been also shown that using a polynomial description of a PA does not lead to a nonzero AM/PM conversion. Moreover, a necessary condition of occurrence of an AM/AM conversion in this kind of modelling is existence of at least one nonzero polynomial coefficient associated with its odd terms of degree greater than one.
5
Content available On Definition of Operator o for Weakly Nonlinear Circuits
Borys A.
International Journal of Electronics and Telecommunications
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2016
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Vol. 62, No. 3
253--259
EN
For the first time, operator o appeared in the literature on weakly nonlinear circuits in a Narayanan’s paper on modelling transistor nonlinear distortion with the use of Volterra series. Its definition was restricted only to the linear part of a nonlinear circuit description. Obviously, as we show here, Narayanan’s operator o had meaning of a linear convolution integral. The extended version of this operator, which was applied to the whole nonlinear circuit representation by the Volterra series, was introduced by Meyer and Stephens in their paper on modelling nonlinear distortion in variable-capacitance diodes. We show here that its definition as well as another definition communicated to the author of this paper are faulty. We draw here attention to these facts because the faults made by Meyer and Stephens were afterwards replicated in publications of Palumbo and his coworkers on harmonic distortion calculation in integrated CMOS amplifiers, and recently in a paper about distortion analysis of parametric amplifier by H. Shrimali and S. Chatterjee. These faults are also present in some class notes for students, which are available on WWW-pages.
6
Content available Nonlinear Distortions in Electroacoustic Devices
Dobrucki A.
Archives of Acoustics
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2011
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Vol. 36, No. 2
437-460
EN
The task of electroacoustic devices is a transmission of audio signals. The transmitted signal should be distorted as little as possible. Nonlinear distortions are the distortions depending on signal level. The types of nonlinear distortions as well as their measures are presented in the paper. The weakest device in an electroacoustic chain is a loudspeaker. It causes the greatest degradation of the signal. It is usually the most nonlinear part of the electroacoustic system. The nonlinearities in loudspeakers are described in details. Other types of nonlinear distortions as transient intermodulation in power amplifiers and distortions caused by the A/C sampling are also presented.
7
The impact of digital filter parameters on the results of nonlinear distortion measurements in loudspeakers : simulation process
Dobrucki A., Siczek R.
Elektronika : konstrukcje, technologie, zastosowania
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2010
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Vol. 51, nr 3
34-38
EN
In this article the impact of changes of digital filter parameters on nonlinear distortion measurements in loudspeakers is presented. For measurements the measurement method of broad-band noise was used. The procedure of measurement of nonlinear distortion in loudspeakers with the use of digital filters with white or pink noise excitation is described.
PL
W artykule przedstawiono wpływ zmiany parametrów filtrów cyfrowych na wyniki pomiarów zniekształceń nieliniowych w głośnikach. Metodą pomiarową jest metoda szumu szerokopasmowego. Opisano sposób wykonania pomiarów zniekształceń nieliniowych głośników z wykorzystaniem filtrów cyfrowych przy pobudzeniu układu szumem białym lub różowym.
8
Content available remote Elimination of nonlinearity with discontinuities (of dead zone) from static characteristic of converter
Domańska A.
Metrology and Measurement Systems
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2008
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Vol. 15, nr 4
491-500
EN
The characteristics of real converters, including sensors, are - to a smaller or larger extent - nonlinear. Nonlinearity may result from the technologies applied to produce the converter or from the type of processing to be realized by the converter. With respect to the mathematical model describing the characteristics, they can be characteristics with smooth nonlinearity or nonlinearity with discontinuities. The author presented the problem of elimination of nonlinearity with discontinuities from the converter characteristic, which appears in the small-value area, i.e. in the dead zone, with a method utilizing the technique of added noise (dither). The properties of a converter with modified characteristic are shown: the ability to process input signals that previously could not be processed because their values were within the dead zone; removal of discontinuities in the output signal within the range of small values.
9
Content available remote Pulsed nonlinear acoustic fields from clinically relevant sources: numerical calculations and experiments results
Wójcik J., Kujawska T., Nowicki A.
Archives of Acoustics
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2008
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Vol. 33, No. 4
565-571
EN
The goal of this work was to verify experimentally the applicability of the recently developed Time-Averaged Wave Envelope (TAWE) method [1] as a tool for fast prediction of pulsed nonlinear pressure fields from focused nonaxisymmetric acoustic sources in attenuating media. The experiments were performed in water at the fundamental frequency of 2.8 MHz for spherically focused (focal length F = 80 mm) square (20x20 mm) and rectangular (10x25 mm) sources similar to those used in the design of 1D linear arrays operating with ultrasonic imaging systems. The experimental results obtained with 10-cycle tone bursts at three different excitation levels corresponding to linear, moderately nonlinear and highly nonlinear propagation conditions (0.045, 0.225 and 0.45 MPa on-source pressure amplitude, respectively) were compared with those yielded using the TAWE approach. Comparison of the experimental and numerical calculations results has shown that the TAWE approach is well suited to predict (to within ±1 dB) both the spatial-temporal and spatial-spectral pressure variations in the pulsed nonlinear acoustic beams.
10
Content available Vertical cavity surface emitting lasers in radio over fiber applications
Marozsák T., Udvary E.
Journal of Telecommunications and Information Technology
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2003
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nr 1
36-40
EN
Theoretical and experimental study of using direct modulated vertical cavity surface emitting lasers in radio over fiber applications is presented. The nonlinear distortion and signal to noise ratio are investigated and evaluated in case of short-range multi-carrier transmission. Nonlinear characterization and comparison of the different kind of semiconductor lasers are also presented.
11
Content available remote Measurements of quadratic electrooptic coefficients in noncentrosymmetric crystals - analysis of the nonlinear distorsion in experimental setup
Ledzion R., Kucharczyk W.
Scientific Bulletin. Physics / Lodz University of Technology
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2001
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Vol. 21
51-57
EN
Nonlinear distorsions in experimental set-up employed to determine the quadratic electrooptic effect are determined. It is shown that errors due to the nonlinear distorsions may be neglected.
PL
Zmierzono nieliniowe zniekształcenia wnoszone przez układ pomiarowy wykorzystywany do pomiarów kwadratowego efektu elektrooptycznego. Wykazano, że wprowadzają one zaniedbywalnie mały błąd.
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