Experimentation for development of underwater acoustic video camera: In experiment dock

Abukawa, Kazuki; Matsumoto, Sayuri; Hirabayashi, Taketsugu; Shirai, Kohji; Sato, Tomoo; Iida, Hiroshi; Nanri, Mitsuhiko; Yoshie, Muneo; Katakura, Kageyoshi; Takahashi, Koji

doi:10.23919/oceans.2015.7401944

Cited by 3 publications

(1 citation statement)

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“…However, the required distance range is the acoustic near field of the 3D underwater acoustic video camera, and the transmission field is changed in a complicated manner; hence, false acoustic images tend to be captured. [22][23][24] To solve this problem, we studied the self-focusing effect of the polarization-inverted transmitter by up-chirp signal driving for subaperture arrays in the acoustic near field. 25) In this study, we examined these effects experimentally by (1) self-focusing without giving a delay to the driving up-chirp signal of each element of the polarization-inverted transmitter, (2) improving the focusing effect of the subaperture, and (3) moving the focal point to change the frequency component of the driving up-chirp signal.…”

Section: Introductionmentioning

confidence: 99%

Verification of resolution on self-focusing effect of polarization-inverted transmitter by up-chirp signal for subaperture array

Abukawa

Matsumoto

Sato

et al. 2018

Jpn. J. Appl. Phys.

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In this study, we experimentally proved the relationship between the number of subapertures and the self-focusing effect of a polarization-inverted transmitter by up-chirp signal driving. First, experiments on the focusing effect by aperture division were carried out using a prototype polarization-inverted transmitter. As a result, the beam width was improved by dividing the aperture. By increasing the number of aperture divisions, the beam width was reduced and the distance resolution was improved proportionally to the number of divisions. Finally, the beam width at the focal point was measured by changing the frequency component of the up-chirp signal driving the transmitter. Dependent on the focal point, the beam width did not change significantly. As a result, a focal point could be formed within the near field owing to the self-convergence phenomenon of the polarization-inverted transmitter and the convergence effect caused by aperture division.

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Section: Introductionmentioning

confidence: 99%