Experimental study on waveguide invariant passive ranging based on buoy

The important feature of ocean waveguides is that there is a stable and observable interference structure in the low-frequency sound field.This interference structure can be described by only one scalar parameter beta, which is called waveguide invariant. It reflects the relationship between distance, frequency and interference fringe slope. Therefore, the motion parameter information of the target can be obtained by analyzing the LOFAR diagram of the radiated noise of a moving ship, as a kind of equipment which is easy to be placed in the marine environment, buoy has been widely used in the field of underwater acoustics. In this paper, using the buoy test data, the distance information of the passive target is obtained by the waveguide invariant method, which overcomes the defect that the traditional buoy ranging method needs multiple buoys. The distance estimation of the passive target is realized only by a single buoy, and the distance measurement error within the effective range is no more than 10%.