Person: Carlosena García, Alfonso
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Carlosena García
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Alfonso
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0000-0002-7146-4043
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Publication Open Access Sensing in coin discriminators(IEEE, 2007) Carlosena García, Alfonso; López Martín, Antonio; Arizti, Fernando; Martínez de Guereñu, Ane; Pina Insausti, José L.; García Sayés, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThis paper describes the technologies used in coin discriminator devices, stressing the improvements and novel mechanisms introduced by the authors in the past few years as a result of the cooperation with one leading company in the vending sector. Emphasis is put on how low-cost sensors are used to characterize coins (or tokens) and discriminate them from their counterfeits.Publication Open Access Vibrato in singing voice: the link between source-filter and sinusoidal models(Springer Open, 2004) Carlosena García, Alfonso; Arroabarren Alemán, Ixone; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThe application of inverse filtering techniques for high-quality singing voice analysis/synthesis is discussed. In the context of source-filter models, inverse filtering provides a noninvasive method to extract the voice source, and thus to study voice quality. Although this approach is widely used in speech synthesis, this is not the case in singing voice. Several studies have proved that inverse filtering techniques fail in the case of singing voice, the reasons being unclear. In order to shed light on this problem, we will consider here an additional feature of singing voice, not present in speech: the vibrato. Vibrato has been traditionally studied by sinusoidal modeling. As an alternative, we will introduce here a novel noninteractive source filter model that incorporates the mechanisms of vibrato generation. This model will also allow the comparison of the results produced by inverse filtering techniques and by sinusoidal modeling, as they apply to singing voice and not to speech. In this way, the limitations of these conventional techniques, described in previous literature, will be explained. Both synthetic signals and singer recordings are used to validate and compare the techniques presented in the paper.Publication Open Access Design of low-cost smart accelerometers(Universitat Politècnica de Catalunya, 2005) Carlosena García, Alfonso; López Martín, Antonio; Massarotto, Marco; Cruz Blas, Carlos Aristóteles de la; Lecumberri Villamediana, Pablo; Gómez Fernández, Marisol; Pintor Borobia, Jesús María; Gárriz Sanz, Sergio; Ingeniería Eléctrica y Electrónica; Matemáticas; Ingeniería Mecánica, Energética y de Materiales; Ingeniaritza Elektrikoa eta Elektronikoa; Matematika; Mekanika, Energetika eta Materialen IngeniaritzaThe goal of this project is to design a low-cost smart accelerometer, making use of a piezoelectric element as basic sensing material, and adding a mixed-mode conditioning circuit.Publication Open Access Signal processing in ocean bottom seismographs for refraction seismology(IEEE, 2006) Rodríguez Barbarin, Iban; Mànuel Lázaro, Antonio; Carlosena García, Alfonso; Bermúdez, Antoni; Río, Joaquín del; Panahi, Shahram Shariat; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThis paper presents some experimental results on the application of signal processing techniques to underwater seismic signals. The novelty of this paper stems from the fact that it is the first paper, to the best of the author’s knowledge, dealing with a comprehensive processing of signals obtained from active refraction seismology. In particular, this paper has adapted known signal processing techniques to problems such as time of arrival detection (TOA), compression and representation through conventional images (hodocrones) used in underwater seismology. The work is part of a wider project aimed at the design of a small ocean bottom seismometer (OBS) undertaken by several research and development groups in Spain. This sophisticated easy to handle equipment allows recording useful active and passive seismicity information.Publication Open Access Multichannel blind deconvolution of impulsive signals(2005) Lecumberri Villamediana, Pablo; Gómez Fernández, Marisol; Carlosena García, Alfonso; Matemáticas; Ingeniería Eléctrica y Electrónica; Matematika; Ingeniaritza Elektrikoa eta ElektronikoaIn this communication, the problem of blind deconvolution of transient, impulsive signals in a multichannel environment is addressed. This kind of signals arise naturally, or are used as external excitation, in many mechanical and acoustical systems and can only be observed indirectly, after propagation through the medium. Blind deconvolution or identi cation methods published to date are not suitable for recovering these sources or the system response, as identi ability conditions are not met. We fully develop here a deterministic subspace method for the blind deconvolution in a multichannel environment which does not impose any restrictions on the excitation signals or on the impulse response of propagation channels, apart from nite length and channel diversity. The method is also extended to cope with signals in noisy environments.Publication Open Access Design of MOS-translinear multiplier/dividers in analog VLSI(Hindawi Publishing Corporation, 2000) López Martín, Antonio; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaA general framework for designing current-mode CMOS analog multiplier/divider circuits based on the cascade connection of a geometric-mean circuit and a squarer/ divider is presented. It is shown how both building blocks can be readily obtained from a generic second-order MOS translinear loop. Various implementations are proposed, featuring simplicity, favorable precision and wide dynamic range. They can be successfully employed in a wide range of analog VLSI processing tasks. Experimental results of two versions, based on stacked and folded MOS-translinear loops and fabricated in a 2.4-1am CMOS process, are provided in order to verify the correctness of the proposed approach.Publication Open Access Glottal spectrum based inverse filtering(ISCA, 2003) Arroabarren Alemán, Ixone; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaIn this paper a new inverse filtering technique for the time-domain estimation of the glottal excitation is presented. This approach uses the DAP modeling for the vocal tract characterization, and a spectral model for the derivative of the glottal flow. This spectral model is based on the spectrum of the KLGLOTT88 model for the glottal source. The proposed procedure removes the glottal source from the spectrum of the speech signal in an accurate manner, particularly for highpitched signals and singing voice, and the estimated glottal waveforms present less amount of formant ripple.Publication Open Access Unified analysis of glottal source spectrum(ISCA, 2003) Arroabarren Alemán, Ixone; Zivanovic, Miroslav; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThe spectral study of the glottal excitation has traditionally been based on a single time-domain mathematical model of the signal, and the spectral dependence on its time domain parameters. Opposite to this approach, in this work the two most widely used time domain models have been studied jointly, namely the KLGLOTT88 and the LF models. Their spectra are analyzed in terms of their dependence on the general glottal source parameters: Open quotient, asymmetry coefficient and spectral tilt. As a result, it has been proved that even though the mathematical expressions for both models are quite different, they can be made to converge. The main difference found is that in the KLGLOTT88 model the asymmetry coefficient is not independent of the open quotient and the spectral tilt. Once this relationship has been identified and translated to LF model, both models are shown to be equivalent in both time and frequency domains.Publication Open Access Modelling of vibrato production(2004) Arroabarren Alemán, Ixone; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaIn this paper, a novel Non-Interactive Source-Filter model for singing voice, incorporating vibrato, is proposed. In this way the periodic frequency variation, peculiar to vibrato is included in a simplified signal model for singing voice production. The inclusion of vibrato will further allow to relate two distinct signal models for the voice: The Non Interactive Source-Filter and the Sinusoidal Models. In this way, the Instantaneous Amplitude and Instantaneous Frequency of the harmonics, which are intrinsically Sinusoidal Model parameters, will be related to the glottal source and vocal tract response, typical of the Source-Filter model. Thanks to the proposed model, the most relevant acoustic features of vibrato will be related to the voice production mechanisms.Publication Open Access Analysis and synthesis of vibrato in lyric singers(2002) Arroabarren Alemán, Ixone; Carlosena García, Alfonso; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaIn this paper two aspects of the vibrato signal characterisation are presented. First, an analysis method, which breaks down the musical signal into its different partials, and decomposes them into two separate contributions: AM and FM. This allows an objective characterization of the vibrato according to musical parameters. Second, a procedure for vibrato synthesis is proposed, based on the previous analysis. Even though the results of the synthesis are not fully satisfactory, they shed new light on the vibrato modeling.