Parametric modeling of photometric signals

This paper studies a new model for photometric signals under high flux assumption. Photometric signals are modeled by Gaussian autoregressive processes having the same mean and variance denoted Constraint Gaussian Autoregressive Processes (CGARP's). The estimation of the CGARP parameters is discussed. The Cramér Rao lower bounds for these parameters are studied and compared to the estimator mean square errors. The CGARP is intended to model the signal received by a satellite designed for extrasolar planets detection. A transit of a planet in front of a star results in an abrupt change in the mean and variance of the CGARP. The Neyman–Pearson detector for this changepoint detection problem is derived when the abrupt change parameters are known. Closed form expressions for the Receiver Operating Characteristics (ROC) are provided. The Neyman–Pearson detector combined with the maximum likelihood estimator for CGARP parameters allows to study the generalized likelihood ratio detector. ROC curves are then determined using computer simulations

Analyse statistique de SMF pour l'étude des signaux à phase polynômiale

L'algorithme SMF permet d'estimer le coefficient du terme de plus haut degré d'un signal à phase polynômiale et à amplitude constante à partir de moments invariants dans le temps des observations. Cet algorithme fait intervenir des moments d'ordre inférieur à la transformée de phase polynômiale (TPP) et ne nécessite pas de maximisations. La contribution majeure de cette communication est une expression analytique de la variance de l'erreur d'estimation de SMF à fort rapport signal sur bruit. Ce résultat permet de montrer l'efficacité asymptotique de SMF si une dépendance entre le nombre de moments et le nombre d'observations est introduite. En outre, il permet de mettre en évidence la supériorité de SMF par rapport à TPP moyennant un choix judicieux du nombre de moments

Application de la théorie de l'information pour l'extraction passive radar en guerre électronique marine

Dans l'environnement électromagnétique naval, les impulsions émises par les radars sont recueillies par des récepteurs passifs. Ces impulsions sont regroupées en blocs selon la similitude de certains paramètres. Le but de cette étude est alors de mettre en place un critère de regroupement des blocs d'impulsions pour reconstruire les formes d'ondes émises par les radars. Cela doit permettre d'obtenir une meilleure qualité d'identification d'émetteur. La méthode de regroupement des blocs utilisée est une méthode de fusion basée sur un calcul d'entropie, l'entropie permettant d'estimer le degré de désordre du signal obtenu pour les cas de fusion envisagés

Performance indicators of the correlation process for non ambiguous doppler frequency estimation in multiple PRF radars

International audienceThis communication investigates the performance of alias-free Doppler frequency estimation in multiple Pulse Repetition Frequency radar systems. Three performance indicators are proposed for Doppler ambiguity resolution algorithms based on the use of a correlation interval of given width : probabilities of correlation, of false correlation and of false measurement. Under the assumption of Gaussian errors on the ambiguous frequencies estimates for each PRF, closed forms (function only of the interval width, the PRF values and the estimation variance on the ambiguous frequencies) are derived for these indicators. Some examples of the expected behavior of MPRF systems obtained with these indicators are presented and discussed

Optimal joint adaptive estimation of parameter and state of a linear stochastic system with application to tracking

An extension is described in this paper of the optimal joint estimation of parametres and state in stochastic linear systems, to the single input-single output situation, which is the kind of system that appears in the tracking of the position of an unknown flying object in one direction if interaction between coordinates is neglected. An application to radar tracking follows, with special emphasis on the description of the discrete filtering algorithm that processes the data given by a radar. Some results of the computer program with simulated and with real data, are disclosed

Optimal joint adaptive estimation of parameter and state of a linear stochastic system with application to tracking

An extension is described in this paper of the optimal joint estimation of parametres and state in stochastic linear systems, to the single input-single output situation, which is the kind of system that appears in the tracking of the position of an unknown flying object in one direction if interaction between coordinates is neglected. An application to radar tracking follows, with special emphasis on the description of the discrete filtering algorithm that processes the data given by a radar. Some results of the computer program with simulated and with real data, are disclosed

Théâtre et pouvoir

Actes du IVe Colloque International sur le théâtre, domaines hispanique, hispano-américain et mexicain, en France, organisé les 8, 9 et 10 octobre 1998 à l’Université de Perpignan, par le Centre de Recherches Ibériques et Latino-américaines de l’Université de Perpignan