| Project/Area Number |
17560372
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Measurement engineering
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| Research Institution | Osaka University |
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Principal Investigator |
SAKUTA Ken Osaka University, Graduate School of Engineering Science, Associate Professor, 大学院基礎工学研究科, 助教授 (70221273)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Active noise control / magnetic noise / radio frequency interference / phase control / digital signal processing / field programmable gate array / 電磁波雑音 / SQUID |
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| Research Abstract |
It is important to remove large environmental noise in measurement using hypersensitive sensors without electromagnetic shielding. This research topic has aimed to decrease the environmental noise input to the sensor by active noise control (ANC). The target frequency regions were several hundreds Hz or less and the MHz region.
In the low frequency region, the measurement system assumed the nondestructive testing using the superconducting quantum interference device (SQUID) magnetometer as a sensor. The noise cancellation was attempted using the negative feedback loop composition. To prevent the signal from attenuating, this feedback loop contains the low pass filter (LPF). The large low-frequency noise was extracted by the LPF firstly. Then a signal with an antiphase component was fed back to a compensation circuit. Finally, the magnetic field was canceled by the compensation magnetic field. This ANC system made scanning measurement using robot-arms become possible, while the large noise was observed in the case of steel sample without the ANC system. It is important to choose the optimum characteristics of the LPF in order to get high sensitivity of detection.
On the other hand, the environmental noise in the MHz radio-frequency region, so-called radio frequency interference (RFI) was attempted to be reduced by the ANC system. Firstly, the ANC system including a phase and amplitude control circuit has been designed to allow precise adjustments of the phase and the amplitude of the anti-phase wave against the noise waves in the MHz region. The ANC system suppressed this sinusoidal wave to the white noise level by about 54 dB. Next, the feasibility of the ANC system for MHz RFI that used the digital signal processing was studied for high speed processing. This ANC system suppressed the MHz sinusoidal waves effectively. The amount of reduction was about 40 dB.
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