Precise positioning of a transponder placed on a sea floor. 2

For pt.1 see J. Soc. Naval Architects Japan, vol.188 (2000). In the previous paper, it was shown that not only the position of a bottom transponder but also the underwater acoustic velocity distribution can be determined, if the position of surface transponders and ranges between the surface and bottom transponders are known. In the present paper, the theory is extended to include the effects of current The basic nonlinear equations are obtained by a variational principle. Some two-dimensional numerical calculations are conducted, and the convergence of the iteration calculations is verified. The numerical results show that the effects of current can be obtained by the present method and can't be neglected for precise positioning.