海洋音響学会誌
Online ISSN : 1881-6819
Print ISSN : 0916-5835
ISSN-L : 0916-5835
論文
超音波水中距離測定における時間反転併用の位相考慮型SC-AFM信号の効果について
五十部 正拓陶 良
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ジャーナル フリー

2022 年 49 巻 3 号 p. 87-95

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To acquire a received signal with broadband width and a high signal-to-noise ratio (SNR) by using a time reversal (TR) method for target ranging, we had developed a sensitivity-compensated amplitude- and frequency-modulated (SC-AFM) signal. The SC-AFM signal has two-order sensitivity compensation to ensure the TR reference transmitting a signal with one-order sensitivity compensation. In that previous work however, the phase distortion of sensitivity was not taken into account in the calculation of the second-order compensation. In the present study, considering the possibility that the phase distortion could unexpectedly influence the shape of the time-domain TR reference signal, we propose a phase-aware SC-AFM signal and studied its ability to enhance the transmitting energy of the TR reference signal and thus improve the accuracy of target ranging. The experimental results show that by using the phase-aware SC-AFM signal,(i) the normalized power of a received signal of its direct wave is enhanced to approx. 0.41 dB,(ii) the SNR of compressed signals for distance measurement is improved to an average of >0.4 dB, and (iii) the accuracy of distance measurement is improved by >3%. Although these quantitative results would depend on the experimental set-up and conditions, they indicate that the phase-aware SC-AFM signal’s efficiency can be expected for higher-accuracy target ranging.

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