1995 Fiscal Year Final Research Report Summary
DEVELOPMENT OF SIGNAL PROCESSING ULTRASONIC ARRAY-SENSOR
| Project/Area Number |
06650451
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
計測・制御工学
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| Research Institution | YAMAGATA UNIVERSITY |
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Principal Investigator |
TAMURA Yasutaka Yamagata University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40171904)
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| Co-Investigator(Kenkyū-buntansha) |
AKATSUKA Takao Yamagata University, Faculty of Engineering, Professor, 工学部, 教授 (80091875)
KOYAMA Kiyohito Yamagata University, Faculty of Engineering, Professor, 工学部, 教授 (60007218)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Ultrasonic array sensor / Signal processing / Controll of directivity / Phase conjugate wave / Piezo-electrical polymer transducer |
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| Research Abstract |
We have developed a ultrasonic array-sensor, encoding sperture (EA), which multiplex spatially distributed information of wavefront. We can control the signal processing function by changing transmitted waveforms.
Following results are obtained :
1. We have constructed the data acquisition system. A-2ch EA transducer was constructed by using P (VDF-TrFE) copolymer films according to an M-sequence. The array was constructed with a transmitter on the same film, then the positioning problem of the transducers are reducod. The electrostatic sealed significantly reduced the noise, and no averaging was needed.
2. A new imaging operator was developed by SVD of the transfer matrix in the frequency domain. The calibration data is obtained using actual output waveforms corresponding to a target scanned along lines. A point target can be imaged with reasonable quality by the operator. The proposed technique provided images with high quality by a small number of data acquisitions and by a small scanning range of the transducer. The relative level of averaged artifacts is reduced by -7dB.
3. A new selective focusing method is proposed for echolocation system. Transducers are constructed to a liner array coded with a binary sequence. The array converts a wavefront to a serial signal. Selective focusing is realized by transmitting a time-reversal waveforms. This enables us to control a focusing pattern with serial transmitting singal. The technique was applied to the adaptive focusing which select the object of maximum target strength. The unneeded signal level was reduced to-4dB by two iteration, this level, however, was increased with iteration number over two.
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Research Products
(8 results)
