Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.

Abstract: A system and method of horizontal wave measurement is disclosed. The system for measuring the directional spectrum of waves in a fluid medium having a substantially planar surface may include a sonar system having a plurality of transducers for generating respective acoustic beams and receiving echoes from one or more range cells located substantially within the beams, at least one of the plurality of acoustic beams being angled non-orthogonally to at least one other of the plurality of acoustic beams. The method may calculate the directional spectrum associated with the waves from the received echoes.

Abstract: A system and method of horizontal wave measurement is disclosed. The system for measuring the directional spectrum of waves in a fluid medium having a substantially planar surface may include a sonar system having a plurality of transducers for generating respective acoustic beams and receiving echoes from one or more range cells located substantially within the beams, at least one of the plurality of acoustic beams being angled non-orthogonally to at least one other of the plurality of acoustic beams. The method may calculate the directional spectrum associated with the waves from the received echoes.