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Yoshihiro Okubo

Bio: Yoshihiro Okubo is an academic researcher. The author has contributed to research in topics: Standing wave & Radar. The author has an hindex of 2, co-authored 3 publications receiving 36 citations.

Papers
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Journal ArticleDOI
TL;DR: This work proposes a new method for measuring distances down to zero meters without expanding the frequency range using an analytic signal, which is a complex sinusoidal signal obtained by observing the standing wave with multiple detectors.
Abstract: Various types of radars have been developed and used until now-such as Pulse, FM-CW. and Spread Spectrum. Additionally, we have proposed another type of radar which measures distances by using standing wave. We have named it as Standing Wave Radar. It has a shorter minimum detectable range and higher accuracy compared to other types. However, the radar can not measure distances down to zero meters like other types of radars. Minimum detectable range of the standing wave radar depends on a usable frequency range. A wider frequency range is required if we need to measure shorter distances. Consequently, we propose a new method for measuring distances down to zero meters without expanding the frequency range. We use an analytic signal, which is a complex sinusoidal signal. The signal is obtained by observing the standing wave with multiple detectors. We calculate distances by Fourier transform of the analytic signal. Moreover, we verify the validity of our method by simulations based on numerical calculation. The results show that it is possible to measure distances down to zero meters. In our method, measurement errors are caused by deviations of position and gain of the detectors. They are around 10cm at the largest if the gain deviations are up to ±1% and the position deviations are up to ±6% of the spacing between the detectors. Prevalent radars still have a common defect that they can not measure distances from zero to several meters. We expect that the defect will be eliminated by putting our method into practical use.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a standing wave radar with a minimum detection distance of about 2 m when the frequency bandwidth is 76 MHz and verified the measurement principle by numerical simulation.
Abstract: In general, it is difficult to measure short distances by radar, which has a minimum detection distance of several meters. The standing wave radar proposed by the present authors has a minimum detection distance of about 2 m when the frequency bandwidth is 76 MHz. A solution to reduce the minimum detection distance is to increase the frequency bandwidth. This is not realistic due to limits imposed by radio regulations. The authors have proposed a method with measurable distances down to 0 m without enlarging the bandwidth and have presented the configuration and the measurement principle. The measurement principle has been verified by numerical simulation. In the present paper, the measurement principle is experimentally verified by using an actual standing wave radar and the realizability of a standing wave radar with measurement capability down to 0 m is confirmed. It is shown that the distance to the target at locations closer than the minimum detection distance of 2 m (0.14, 0.3, 0.5, and 1 m) can be measured with an error of several centimeters for a frequency bandwidth of 76 MHz at 24 GHz. For distances less than 0.14 m, the target could not be placed closer than 0.14 m due to positional interference of the target and the antenna in the present experimental environment so that physical confirmation was not possible. However, at the confirmed distance, the range spectrum predicted from the theory is obtained. Hence, it is considered possible to make measurements without special restrictions. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(9): 25– 34, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20375

5 citations


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Patent
14 Jul 2006
TL;DR: In this article, a transmission unit emits an electromagnetic wave having the same frequency f as an output signal from a sending unit in a direction of a measurement axis, and a detecting unit performs synchronous detection on a reflected wave detected by a directional coupler by an in-phase signal and a quadrature signal of the transmission signal.
Abstract: A transmission unit emits an electromagnetic wave having the same frequency f as an output signal from a sending unit in a direction of a measurement axis. A detecting unit performs synchronous detection on a reflected wave detected by a directional coupler by an in-phase signal and a quadrature signal of the transmission signal, and by extracting DC component from the detection signal, detects the in-phase component and quadrature component of the reflected wave. An analysis signal generating unit mixes the in-phase component and quadrature component of the reflected wave and signals having periodicity corresponding to a prescribed distance, and using only one of the resulting side bands, generates an analysis signal. Fourier transform unit finds distance to the object of measurement from a profile obtained by Fourier transform of the analysis signal.

31 citations

Journal ArticleDOI
TL;DR: This paper fundamentally examines the distance estimation method in which acoustical standing wave is used in the research field of microwave radar and focuses its attention on audible sound.
Abstract: In the research field of microwave radar, a range finding method based on standing wave is known to be effective for measuring short distances. In this paper, we focus our attention on audible sound and fundamentally examine the distance estimation method in which acoustical standing wave is used.

26 citations

Journal ArticleDOI
TL;DR: It has been confirmed that short distances to multiple targets, such as the distances of two targets located at 0.5 m and 1 m, can be measured by the fundamental principle of this method applied to measurement of short distance for multiple targets using sound wave.
Abstract: Distance to target is fundamental and very important information in many engineering fields. In some applications sound is often used to measure distances to targets. For this purpose, the time delay of reflected wave is typically used. This method, however, can not measure short distance because the transmitted wave, which has not attenuated enough as of reception of reflected waves, suppresses the reflected waves for short distance. Meanwhile, in the research field of microwave radar, to measure distances to multiple targets even if they are short, a novel method by using standing wave has been recently proposed. In this paper, we apply the fundamental principle of this method to measurement of short distance for multiple targets using sound wave. Specifically, we focus our attention on audible band-limited signal with random phases. To verify the validity and effectiveness of our method, we perform computer simulations and experiments. As a result, it has been confirmed that short distances to multiple targets, such as the distances of two targets located at 0.5 m and 1 m, can be measured by our method.

19 citations

Proceedings Article
12 Dec 2011
TL;DR: Measurement results show detection capabilities of a -20 tlBsm cylinder up to 35 m which is 10 m less than the FAA recommendations, and antenna improvements are discussed for reaching the requirements and system performance.
Abstract: The paper is a joint work between the LEAT (France) and the ENRI (Japan) in the framework of a Sakura project supported by the JSPS and the French Ministry of Foreign Affairs. The purpose is the study of a FOD (Foreign Object Debris) detection system on airport runways. A FM-CW mm-Wave radar working between 76.25 and 76.75 GHz is used together with a high directivity printed reflectarray. Measurement results show detection capabilities of a -20 tlBsm cylinder up to 35 m which is 10 m less than the FAA recommendations. Antenna improvements are discussed for reaching the requirements and system performance as well as the use of calibration objects.

18 citations

Journal ArticleDOI
TL;DR: In this paper, a joint work between the LEAT (France) and the ENRI (Japan) in the framework of a Sakura project supported by the JSPS and the French Ministry of Foreign Affairs is presented.
Abstract: The paper is a joint work between the LEAT (France) and the ENRI (Japan) in the framework of a Sakura project supported by the JSPS and the French Ministry of Foreign Affairs. The purpose is the study of a FOD (Foreign Object Debris) detection system on airport runways. An FM-CW mm-wave radar working between 76.25 and 76.75 GHz is used together with a high directivity printed reflectarray. In addition, a second measurement campaign has been conducted with a 73.8–79.8 GHz (6 GHz band) radar. Measurement results show detection capabilities of a −20 dBsm cylinder up to 35 m that is 10 m less than the FAA recommendations. Antenna improvements are discussed for reaching the requirements and system performance as well as the use of calibration objects.

12 citations