The objectives of this project are: i) to simulate acoustic backscatter time series due to volume reverberation in the sea water, and ii) to develop estimators to determine various characteristics inof the water.
The physics of volume reverberation in water both for continuous media and for discrete scatterers was modelled. The backscattered acoustic field is described in the form of second order statistical moments (auto correlation and cross correlation) of the (stochastic) acoustic waves. These moments drive an echo generator producing synthetic echoes for various transducer input signals. Based on these echoes, estimators have been developed to obtain information from the (sea) water, in particular flow velocity and sediment concentration. The performance of both the model and the estimators have been tested in a laboratory flume. The developed tools (software) should enable instrument manufacturers to design, test and optimize new marine instrumentation under a wide variety of conditions at home, before sailing out for sea trials, thus reducing considerably the costs of the latter.
The simulations are based on (assumed) physical properties inof the water. The product(s) should support to developto get optimum performance of measuring methods based on wideband acoustic volume reverberation. In the present stage the work is confined to: longitudinal (Doppler) and transverse velocity profiling, and refraction index profiling (concentrations). Later applications are temperaturesalinity gradients and turbulence. The product(s) should be capable of replacing (expensive) field tests under poorly known conditions. The work contains the development of a physical model, a signal simulator, and wideband parameter estimators. It includes validation of the model and the estimators by laboratory experiments.