Exploració per tema "Processament del senyal"

Ara es mostren els items 21-40 de 40

    • NDA waveform estimation in the low-SNR regime 

      López Salcedo, José Antonio; Vázquez Grau, Gregorio (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERING INC, 2007-12)
      Article
      Accés obert
      This correspondence addresses the problem of nondata-aided waveform estimation for digital communications. Based on the unconditional maximum likelihood criterion, the main contribution of this correspondence is the ...

    • New FTT bit-reversal algorithm 

      Rius Casals, Juan Manuel; Porrata-Dòria i Yagüe, Ramir de (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1995-04-01)
      Article
      Accés obert
      This correspondence presents a very short, simple, easy to understand bit-reversal algorithm for radix-2 fast Fourier transform (FFT), which is, furthermore, easily extendable to radix-M. In addition, when implemented ...

    • Non-linear graph-based codes for joint source-channel coding 

      Matas Navarro, David; Lamarca Orozco, M. Meritxell; García Frías, Javier (2010)
      Text en actes de congrés
      Accés obert
      We study the behavior of a new family of nonlinear graph-based codes, previously introduced for compression of asymmetric binary memoryless sources, for the joint source-channel coding scenario in which the codewords are ...

    • On the common mode response of fully differential circuits 

      Gasulla Forner, Manuel; Casas Piedrafita, Óscar; Pallàs-Areny, Ramon (Institute of Electrical and Electronics Engineers, 2000)
      Text en actes de congrés
      Accés obert
      Differential circuits are often described by their differential gain and common mode rejection ratio (CMRR). This approach, however, neglects the effect that the common mode signal has on the transient response and stability ...

    • On the zero- and first-order interpolation in synthesized wave for testing purposes 

      Lozano Nieto, Alberto; Rosell Ferrer, Francisco Javier; Pallàs-Areny, Ramon (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1992-12-02)
      Article
      Accés obert
      This paper deals with the quality requirements of synthesized sine waves reconstructed through a zero- or first- order hold for testing purposes, in particular when a switching demodulator is used. In this case, the ...

    • On wideband deconvolution using wavelet transform 

      Rebollo Neira, Laura; Fernández Rubio, Juan Antonio (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1997-07-31)
      Article
      Accés obert
      A discussion on the expression proposed in [1]–[3] for deconvolving the wideband density function is presented. We prove here that such an expression reduces to be proportional to the wideband correlation receiver output, ...

    • Optimization of linear multielement antennas for selection combining by means of a Butler matrix in different MIMO environments 

      Grau Besolí, Alfred; Romeu Robert, Jordi; Blanch Boris, Sebastián; Jofre Roca, Lluís; Flaviis, Franco de (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006-11-30)
      Article
      Accés obert
      An optimized linear multielement antenna (MEA) is presented for selection combining schemes that improves the selection diversity gain and selection diversity capacity in medium and low multipath environments, with ...

    • Positive time-frequency distributions based on joint marginal constraints 

      Rodríguez Fonollosa, Javier (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1996-08-01)
      Article
      Accés obert
      This correspondence studies the formulation of members of the Cohen-Posch class of positive time-frequency energy distributions. Minimization of cross-entropy measures with respect to different priors and the case of ...

    • Probabilistic algorithms for blind adaptive multiuser detection 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Zvonar, Zoran; Rodríguez Fonollosa, Javier (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1998-11-30)
      Article
      Accés obert
      In this paper, two probabilistic adaptive algorithms for jointly detecting active users in a DS-CDMA system are reported. The first one, which is based on the theory of hidden Markov models (HMM’s) and the Baum–Wech ...

    • Robust beamforming for interference rejection in mobile communications 

      Riba Sagarra, Jaume; Goldberg, Jason; Vázquez Grau, Gregorio (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1997-01-01)
      Article
      Accés obert
      The problem of robust beamformer design for mobile communications applications in the presence of moving co-channel sources is addressed. A generalization of the optimum beamformer based on a statistical model accounting ...

    • Second-order parameter estimation 

      Villares Piera, Nemesio Javier; Vázquez Grau, Gregorio (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2005-07-31)
      Article
      Accés obert
      This work provides a general framework for the design of second-order blind estimators without adopting any approximation about the observation statistics or the a priori distribution of the parameters. The proposed ...

    • Spatial filtering for pilot-aided WCDMA systems: a semi-blind subspace approach 

      Mestre Pons, Francesc X.; Rodríguez Fonollosa, Javier (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2003-10-31)
      Article
      Accés obert
      This paper proposes a spatial filtering technique for the reception of pilot-aided multirate multicode direct-sequence code division multiple access (DS/CDMA) systems such as wideband CDMA (WCDMA). These systems introduce ...

    • Spectral iterative algorithm for RCS computation in electrically large or intermediate perfectly conducting cavities 

      Rius Casals, Juan Manuel; Lozano Solsona, Angel; Cardama Aznar, Ángel; Jofre Roca, Lluís (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1994-06-01)
      Article
      Accés obert
      A novel algorithm designed to compute efficiently and accurately the high-frequency electromagnetic scattering from open-ended waveguide cavities is presented. The cavity is converted into a stepped-waveguide model so that ...

    • Statistical reference criteria for adaptive signal processing in digital communications 

      Sala Álvarez, José; Vázquez Grau, Gregorio (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1997-01-01)
      Article
      Accés obert
      A general criterion for the design of adaptive systems in digital communications called the statistical reference criterion is proposed. The criterion is based on imposition of the probability density function of the ...

    • System identification using a linear combination of cumulant slices 

      Rodríguez Fonollosa, José Adrián; Vidal Manzano, José (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1993-07-01)
      Article
      Accés obert
      In this paper we develop a new linear approach to identify the parameters of a moving average (MA) model from the statistics of the output. First, we show that, under some constraints, the impulse response of the system ...

    • The continuous wavelet transform as a maximum entropy solution of the corresponding inverse problem 

      Rebollo Neira, Laura; Fernández Rubio, Juan Antonio (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1999-07-31)
      Article
      Accés obert
      The continuous wavelet transform is obtained as a maximum entropy solution of the corresponding inverse problem. It is well known that although a signal can be reconstructed from its wavelet transform, the expansion is ...

    • The floating capacitor as a differential building block 

      Gasulla Forner, Manuel; Jordana Barnils, José; Pallàs-Areny, Ramon; Torrents Dolz, Josep M. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1998-02-28)
      Article
      Accés obert
      This paper analyzes the advantages and limitations of using the floating- (or flying-) capacitor technique as a building block with differential input and either differential or single-ended output to implement voltage ...

    • The IST METRA Project 

      Rodríguez Fonollosa, Javier; Heikkilä, Markku; Kermoal, Jean Philippe; Mestre Pons, Francesc X.; Pagès Zamora, Alba Maria; Pollard, Adam; Schumacher, Laurent; Ylitalo, Juha; Gaspa Maynou, Roger (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2002-07-31)
      Article
      Accés obert
      This article summarizes the main achievements of the Multi-Element Transmit and Receive Antennas (METRA) Project, an IST research and technological development project carried out between January 2000 and June 2001 by ...

    • Threshold and timing errors of 1 bit / 2 level digital correlators in earth observation synthetic aperture radiometry 

      Camps Carmona, Adriano José; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Bará Temes, Francisco Javier; Lluch, J. A. (IEE-INST ELEC ENG, 1997-04-30)
      Article
      Accés obert
      Analytical expressions for the errors generated in 1 bit/2-level digital correlators (IB/2L) are derived: threshold errors in comparators and timing (skew and jitter) errors in samplers. These expressions are used to specify ...

    • Wigner higher-order spectra: definition, properties, computation and application to transient signal analysis 

      Rodríguez Fonollosa, Javier; Nikias, Chrysostomos L. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1993-01-31)
      Article
      Accés obert
      The Wigner higher order moment spectra (WHOS) are defined as extensions of the Wigner-Ville distribution (WD) to higher order moment spectra domains. A general class of time-frequency higher order moment spectra is also ...