Communications – electrical: acoustic wave systems and devices – Distance or direction finding – With beam steering – scanning – or focussing
Patent
1995-07-31
1997-10-21
Lobo, Ian J.
Communications, electrical: acoustic wave systems and devices
Distance or direction finding
With beam steering, scanning, or focussing
367103, 367119, G01S 386
Patent
active
056803710
ABSTRACT:
A broadband sonar system in which a broadband output from a conventional narrowband sonar sensor array is used to capture broadband acoustical input signals. A single broadband beamformer receives the input from each of the sensors (such as hydrophones) of the array. The broadband output signal from each sensor of a particular subarray is coupled to a corresponding one of a plurality of first filters. Each first filter emphasizes those frequencies of each subarray which have the least noise. In addition, the output is attenuated for frequencies below the design frequency, with lower frequencies being attenuated to a greater degree than higher frequencies. A plurality of second and third filters, each corresponding to a subarray, are provided to compensate for the effects of the frequency and sensor spacing on the signal as the beam rotates. In the preferred embodiment of the present invention, the second filters attenuate certain channels as the beam approaches broadside in a manner that provides near optimum performance. The transfer function of each of the second filters remains constant over a range of beam angles computed by a sector allocation processor. When the beam angle being computed is outside the range, a new transfer function is presented to each second filter by the sector allocation processor. The outputs of all of the channels are presented to a single broadband focused sector beamformer which sums the outputs from each channel in accordance with a beamforming algorithm.
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Thurstone et al., "A new ultrasound imaging technique employing two-dimensional electronic beam steering", Dept. of Biomedical Engineering, Duke University Jun. 27, 1978.
Arete Engineering Technologies Corporation
Lobo Ian J.
Rogitz John L.
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