Characterization of Underwater acoustic channel for a relative positioning system

An Underwater acoustic channel is characterized as time-varying, multipath environment. In order to get a better location result, we firstly analysised the environment in the water tank and modeled it in this paper. Using long time observation, the successive time-variant impulse response and the statistical parameters changing is obtained. All these parameters can effectively avoid multipath (indirect) signals which can be mistaken for the direct signal that would affect the positioning system for a relative positioning system. Compared with the absolute positioning systems, the relative positioning systems don't need an external infrastructure. Only the distances between the buoys are used to obtain their position. The results showed that using LFM signal can get the stable location result. Meanwhile the positioning system is easy on the equipments which has great application future for the specific environment, such as the animal breeding and dolphin protection.