Cornel Ioana

Learn More
The high-order ambiguity function (HAF) was introduced for the estimation of polynomial-phase signals (PPS). Currently the HAF suffers from noise-masking effects and from the appearance of undesired cross terms in the presence of multi-components PPS. The multi-lag product HAF (PHAF) concept was then proposed as a way to improve the performances of the HAF.(More)
The high-order ambiguity function (HAF) was introduced for the estimation of polynomial-phase signals (PPS) embedded in noise. Since the HAF is a nonlinear operator, it suffers from noise-masking effects and from the appearance of undesired crossterms whenmulticomponents PPS are analyzed. In order to improve the performances of the HAF, the multi-lag HAF(More)
This paper introduces a new generalized complex-lag moment which produces joint time-"phase derivatives" distributions. For the choice of the time-"first-order phase derivative," which stands for time-frequency representation, this distribution can be seen as a form of the Wigner-Ville distribution. Moreover, this generalization leads to distributions with(More)
The estimation of the impulse response (IR) of a propagation channel may be of great interest for a large number of underwater applications: underwater communications, sonar detection and localization, marine mammal monitoring, etc. It quantifies the distortions of the transmitted signal in the underwater channel and enables geoacoustic inversion. The(More)
A time-frequency classifier is applied for human gait classification. Time-frequency (t-f) quadratic distributions are used for time-frequency signal representations. Three specific motions are considered, corresponding to three different scenarios of arm motions which describe free and confined arm swings. The microDoppler signature in the time-frequency(More)
Time-frequency representations constitute the main tool for analysis of nonstationary signals arising in real-life systems. One of the most challenging applications of time-frequency representations deal with the analysis of the underwater acoustic signals. Recently, the interest for dispersive channels increased mainly due to the presence of the wide band(More)
We investigate a characterization of underwater acoustic signals using extracted time-scale features of the propagation channel model for medium-to-high frequency range. The underwater environment over these frequencies causes multipath and Doppler scale changes on the transmitted signal. This is the result of the time-varying nature of the channel and also(More)
Effects of Cauchy integral formula discretization on the concentration of time-frequency (TF) distribution are analyzed. As a result of this discretization, new forms of distributions are produced. In order to increase the accuracy of instantaneous frequency (IF) estimation, two solutions are considered: increasing the number of integration points and(More)