High frequency signal fluctuations in shallow water propagation

In coastal areas, multipath interferences give rise to large fluctuations in received levels, and hence to major difficulties in defining underwater acoustic transmission systems. This paper presents an experimental analysis of high frequency (up to 12 kHz) signal fading from the study of both envelope fluctuations and channel impulse responses. Orders of magnitudes of several parameters such as fading rates, time-bandwidth product, randomicity are given and compared in order to characterise the channel behaviours. They are analysed according to physical conditions of experimentation and to channel geometrical configurations. Envelope probability density functions are also computed, and compared with Rician theoretical distributions