Scholarly Works, Economics

Permanent URI for this collection

https://hdl.handle.net/10919/24332
Research articles, presentations, and other scholarship

Browse

Browsing Scholarly Works, Economics by Subject "Acoustic beamforming"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Beamforming when the sound velocity is not precisely known
    Hinich, Melvin J. (Acoustical Society of America, 1980-08)
    Beamforming is an integral part of most signal processingsystems in active or passive sonars. The delays used to generate a beam are functions of the sound velocity, which depends on temperature, salinity, and pressure. There is a loss in array gain if the delays are incorrectly set. This will occur when the sound velocity in the water surrounding the hydrophones is different from the velocity that was used to set the delays. This paper makes two points: (1) fixed delay line sonars suffer a loss in gain when the true sound speed in the water is different from the velocity that is used to set the delays, and (2) there are signal processing techniques for two- or three-dimensional arrays that yield source bearings that are independent of the true sound velocity. These techniques require variable time delays, which can be realized using digital processing.
  • Thumbnail Image
    Frequency-wave number array processing
    Hinich, Melvin J. (Acoustical Society of America, 1981-03)
    Most array signal processing systems use delay-and-sum beamforming to estimate source bearings. This paper demonstrates the close relationship between beamforming and frequency-wavenumber spectrum analysis. The latter approach has computational advantages over beamforming when the noise is spatially correlated. The wavenumber approach is used to derive the array response of a general linear or planar array to plane wave signals. The statistical properties of the maximum-likelihood estimators of source bearing and amplitude are presented for an array with many elements. Optimal array design is also discussed.