Investigations of hydroacoustic parametric sub-bottom profiler characteristics

Summary form only given. The problem of sub-bottom profiling with large accuracy is urgent and reasonably difficult. The purpose demands the use of high directivity low-frequency wide band acoustic source. The most expedient type of source is a parametric acoustic array. Research on the specific properties of parametric arrays permits one to create a bottom profiler for the shelf, suitable for small-sized vessels for fulfilment of works on geology, marine archeology, ecology, oceanology etc. The power characteristics of parametric systems are little different from conventional sonars. The differences are stipulated by features of parametric arrays. The transmission of energy from pump waves to difference frequency waves is executed within the zone of nonlinear interaction. The authors consider a bottom model consisting of similar layers with flat horizontal borders. The duration of signals is shorter than the propagation time of sound inside the layer and it is possible to select the signals from the bottom and surface of the layer. The reflection factors can be determined for each layer. The received expression permits calculation of the capacity on each frequency pump, necessary to determine bottom sediments in view of their characteristics. The dependence of signal-noise ratio from sediment layer depth and different frequency were calculated. The parametric profiler developed in Taganrog State University of Radio-engineering, is used for the investigation.