Performance improvements of a 50 km acoustic transmission through adaptive equalization and spatial diversity

Adaptive multichannel equalizers have become an important matter of interest in acoustic underwater communications. Their application has made data transmission over long ranges possible. The purpose of this paper is to present an overview of multichannel equalization applied to underwater acoustic transmissions. We analyze the optimal multichannel filtering structures and calculate their performances analytically. Then, we introduce a simple structure and discuss its implementation for real-time applications. Eventually we show some experimental results obtained with this multichannel receiver on a 50 km acoustic link and analyze the improvements generated by spatial combining.