International audienceWe investigate the behaviour of the continuous wavelet and Gabor coefficients in the asymptotic limit, using stationary phase approximations. In particular, we show how, under some additional assumptions, these coefficients allow the extraction of some characteristics of the analysed signal, like for example frequency and amplitude modulation laws. We also briefly discuss applications to spectral lines estimations and matched filtering

International audienceUseful approximation formulae for radiation impedance are given for the reflection coefficients of both infinitely flanged and unflanged rigid-walled cylindrical ducts. The expressions guarantee that simple but necessary physical and mathematical principles are met, like hermitian symmetry for the reflection coefficient (identical behaviour of positive and negative frequencies) and causality for the impulse response. A non causal but more accurate expression is also proposed that is suitable for frequency-domain applications. The formulae are obtained by analytical and numerical fitting to reference results from Levine & Schwinger for the unflanged case and extracted from the radiation impedance matrix given by Zorum-ski for the infinite flanged case

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