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: An acoustic transducer array in which the transducer elements project a plurality of acoustic beams which are not coplanar. In a first embodiment, a cylindrical transducer array housing has each of four transducer elements skewed at an angle relative to the longitudinal axis of the housing. Each acoustic beam formed by the array lies in a unique plane (e.g., in a "pinwheel" configuration), thereby effectively eliminating overlap of the beams throughout the entire profiling range of the array. In another aspect of the invention, acoustic damping material is incorporated throughout selected portions of the transducer housing to mitigate the effects of echoes and undesirable acoustic propagation within the array.

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.