The application of vertical sound intensity in shallow and low frequency sound field

Sound field is described by sound pressure and velocity; this is different from the former concept. This paper has discussed the application of vertical sound intensity stream in shallow and low frequency sound field based on fast field program (FFP) model. The vector signal processing technique is analyzed from physical angle of view, and is made use of to judge the surface ship or submarine. For the past several decades, the sound wave had been simulated by many kinds of mathematical models, such as radial model, kraken model, parabola equation model, multipath expand model, FFP model and so on. These models adapt their own scope, run time, solving precision. FFP model calculates the sound filed by wave theory, and the result is shown as wave number integration, this process uses FFP model, the speed is faster than other models, the result covers both disperse pattern component and continuous pattern component, the result is exacter. In this paper the minor factor is ignored, the boundary and absorbing factor are taken into account.