Separation of instantaneous mixtures of cyclostationary sources and application to digital communication signals

Publication in the conference proceedings of EUSIPCO, Florence, Italy, 200

Modified k-mean clustering method of HMM states for initialization of Baum-Welch training algorithm

International audienceHidden Markov models are widely used for recognition algorithms (speech, writing, gesture, ...). In this paper, a classical set of models is considered: state space of hid- den variable is discrete and observation probabilities are modeled as Gaussian distributions. The models parame- ters are generally estimated with training sequences and the Baum-Welch algorithm, i.e. an expectation maxi- mization algorithm. However this kind of algorithm is well known to be sensitive to its initialization point. The problem of this initialization point choice is addressed in this paper: a model with a very large number of states which describe training sequences with accuracy is first constructed. The number of states is then reduced using a k-mean algorithm on the state. This algorithm is com- pared to other methods based on a k-mean algorithm on the data with numerical simulations

A Wearable Technology Revisited for Cardio-Respiratory Functional Exploration: Stroke Volume Estimation From Respiratory Inductive Plethysmography

International audienceThe objective of the present study is to extract new information from complex signals generated by Respiratory Inductive Plethysmography (RIP). This indirect cardio-respiratory (CR) measure is a well-known wearable solution. The authors applied time-scale analysis to estimate cardiac activity from thoracic volume variations, witnesses of CR interactions. Calibrated RIP signals gathered from 4 healthy volunteers in resting conditions are processed by Ensemble Empirical Mode Decomposition to extract cardiac volume signals and estimate stroke volumes. Averaged values of these stroke volumes (SVRIP) are compared with averaged values of stroke volumes determined simultaneously by electrical impedance cardiography (SVICG). There is a satisfactory correlation between SVRIP and SVICG (r=0.76, p<0.001) and the limits of agreement between the 2 types of measurements (±23%) satisfies the required criterion (±30%). The observed under-estimation (-58%) is argued. This validates the use of RIP for following stroke volume variations and suggests that one simple transducer can provide a quantitative exploration of both ventilatory and cardiac volumes

SDR4all: a Tool for Making Flexible Radio a Reality

International audienceIn this contribution, we describe the potential of SDR4all (Software Defined Radio for all) to solve the bottlenecks and reduce the innovation cycle related to the design and implementation of flexible radio algorithms. SDR4all is a programmable software tool with radio cards for wireless researchers, students and engineers. It enables to implement in software any wireless scheme between two laptops. Using an flexible orthogonal frequency division multiplexing (OFDM) based implementation example, we describe the tool and show the performance of the transmission on a real wireless channel at 2.4 Ghz ISM band

Heart Rate Estimation from Phonocardiogram Signals Using Non-negative Matrix Factorization

International audienceElectrocardiogram (ECG) is classically considered for heart rate (HR) estimation. However in certain conditions, its use may be difficult and alternative techniques, such as phonocardiograhpy (PCG), are investigated. For PCG signals, in most studies, the challenge is to detect and annotate the heart sounds S 1 and S 2 , which may become quasi-impossible in case of noise. In this paper, we present a novel approach of HR estimation from PCG signals based on non-negative matrix factorization (NMF), applied to the spectrogram of PCG, considered as a source-filter model. Compared to state of the art methods, specific considerations based on the signal properties have been included to ensure the reliability of the decomposition. HR estimations obtained from noise-free and noisy real PCG signals are evaluated by comparison to HR estimation from synchronous ECG

Modeling Quasi-Periodic Signals by a Non-Parametric Model: Application on Fetal ECG Extraction

International audience— Quasi-periodic signals can be modeled by their second order statistics as Gaussian process. This work presents a non-parametric method to model such signals. ECG, as a quasi-periodic signal, can also be modeled by such method which can help to extract the fetal ECG from the maternal ECG signal, using a single source abdominal channel. The prior information on the signal shape, and on the maternal and fetal RR interval, helps to better estimate the parameters while applying the Bayesian principles. The values of the pa-rameters of the method, among which the R-peak instants, are accurately estimated using the Metropolis-Hastings algorithm. This estimation provides very precise values for the R-peaks, so that they can be located even between the existing time samples

An Algorithm for Detection of DVB-T Signals Based on Their Second-Order Statistics

We propose in this paper a detection algorithm based on a cost function that jointly tests the correlation induced by the cyclic prefix and the fact that this correlation is time-periodic. In the first part of the paper, the cost function is introduced and some analytical results are given. In particular, the noise and multipath channel impacts on its values are theoretically analysed. In a second part of the paper, some asymptotic results are derived. A first exploitation of these results is used to build a detection test based on the false alarm probability. These results are also used to evaluate the impact of the number of cycle frequencies taken into account in the cost function on the detection performances. Thanks to numerical estimations, we have been able to estimate that the proposed algorithm detects DVB-T signals with an SNR of −12 dB. As a comparison, and in the same context, the detection algorithm proposed by the 802.22 WG in 2006 is able to detect these signals with an SNR of −8 dB

EPIREUN, les crises épileptiques nouvellement diagnostiquées sur l île de la Réunion (taux d incidence, facteurs de risque et prise en charge thérapeutique)

Une enquête épidémiologique d incidence des crises épileptiques nouvellement diagnostiquées sur l île de la Réunion a été menée sur une période de 12 mois, du 01/07/2004 au 30/06/2005. L inclusion des cas concerne les habitants permanents de l île sans limite d âge et s est faite à partir des laboratoires d électrophysiologie publics et privés de l île. Ont été recensées 773 cas de crises provoquées et non provoquées, soit un taux d incidence global annuel de 101,3/100 000 (H : 123,8 ; F : 79,8) et un taux standardisé à la population des Etats-Unis de 119,4/100 000 (H : 141,8 ; F : 97,7). Le Sex-ratio Hommes/Femmes est de 1,5 ; avec une répartition bimodale. Les taux d incidence les plus élevés étant retrouvés chez les personnes âgées, allant jusqu à 500/100 000. Les crises provoquées représentent 135 cas, soit un taux d incidence de 17,7/100 000 (40,7% d étiologie alcoolique, 10,4% d étiologie vasculaire). Les crises non provoquées représentent 638 cas, soit un taux d incidence de 83,6/100 000 (21,2% d étiologie vasculaire, 8,9% d étiologie alcoolique). Soit crises non provoquées avec condition neurologique stable 35,51/100 000, avec condition neurologique évolutive : 3,14/100 000 ; crises non provoquées d origine inconnue : Idiopathiques : 6,29/100 000, Cryptogéniques : 38,65/100 000. Les Etats de mal, avec un taux d incidence de 8,52/100 000, représentent un événement relativement peu fréquent, mais engendrent 18,5% de décès. Le taux d incidence de la maladie épileptique a été estimé à 28,6/100 000, soit un taux plutôt bas aux vue des chiffres globaux, et serait à réévaluer. Les convulsions fébriles de l enfant, incluses et traitées à part, représentent 116 cas, soit un taux d incidence de 161,6/100 000 (H : 195,5 ; F : 126,9). Conclusion : Cette enquête aura montrée un taux d incidence des crises d épilepsie extrêmement élevé, proche de ceux des pays en voie de développement, bien que nous soyons dans un département français. Les principales étiologies retrouvées sont les pathologies vasculaires cérébrales et les pathologies liées à l alcool.GRENOBLE1-BU Médecine pharm. (385162101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Separation of instantaneous mixtures of cyclo-stationary sources

International audienc