Nagano Japan Radio Co.

Nagano Japan, Japan

Nagano Japan Radio Co.

Nagano Japan, Japan
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Suzuki H.,Shinshu University | Fuwa Y.,Shinshu University | Asano D.K.,Shinshu University | Komatsu M.,Okayama University | And 5 more authors.
Proceedings of the 2015 2nd International Conference on Information and Communication Technologies for Disaster Management, ICT-DM 2015 | Year: 2015

For some time, we have been working toward the Realization of a Safe and Secure Society using ICT in Shiojiri-City, Nagano Prefecture. This is a project comprised of two phases: information gathering, and dissemination of information. For information gathering, we are developing systems to confirm the whereabouts of children and the elderly, who are vulnerable in disasters, and systems to gather information on the situation in mountainous regions, rivers etc. For dissemination of information, we are developing systems using broadcast technology for disseminating information to residents, such as disaster information and evacuation warnings derived from the gathered information. This presentation will describe the project goals, the background of the project thus far, and an overview of the developed system. The current situation and plans for the future will also be discussed. © 2015 IEEE.

Hinata H.,Japan National Institute for Land and Infrastructure Management | Fujii S.,University of Ryukyus | Furukawa K.,Japan National Institute for Land and Infrastructure Management | Kataoka T.,Japan National Institute for Land and Infrastructure Management | And 5 more authors.
Estuarine, Coastal and Shelf Science | Year: 2011

Signals from the tsunami waves induced by the March 11, 2011 moment magnitude (Mw) 9.0 Tohoku-Oki earthquake and from subsequent resonances were detected as radial velocity variability by a high-frequency ocean surface radar (HF radar) installed on the eastern coast of the Kii Channel, at a range of about 1000 km from the epicenter along the eastern to southern coasts of Honshu Island. A time-distance diagram of band-passed (9-200 min) radial velocity along the beam reveals that the tsunami waves propagated from the continental shelf slope to the inner channel as progressive waves for the first three waves, and then natural oscillations were excited by the waves; and that the direction of the tsunami wave propagation and the axis of the natural oscillations differed from that of the radar beam. In addition, spectral analyses of the radial velocities and sea surface heights obtained in the channel and on the continental shelf slope suggest complex natural oscillation modes excited by the tsunami waves.The major advantage of the HF radars as tsunami detection is early warning as the tsunami is still far offshore. There is no doubt on this importance beside still technical and operational studies are needed. Our results adds a new role of the HF radars to measure the detailed surface current fields with high spatiotemporal resolution toward understanding detailed processes of resonant response to tsunami waves in coastal regions. © 2011 Elsevier Ltd.

Nose H.,Nagano Prefectural Institute of Technology | Motoyama E.,Nagano Japan Radio Co. | Suzuki H.,Shinshu University | Fuwa Y.,Shinshu University
2012 IEEE Globecom Workshops, GC Wkshps 2012 | Year: 2012

In recent years, there have been many cases of violent crimes against children. As a result there is an increasing need for systems which can identify the current positions of children, and keep watch over them in time slots where they may be alone, such as on the way to and from school. At present, the most typical approach is to have the children carry a wireless terminal so they can be tracked, but the power-saving performance of such devices needs to be improved. As a result, we have proposed a method of estimating the position of children without using GPS, and thereby improved the power-saving performance of the wireless terminals. In addition, we have confirmed through measurement experiments in an experiment field that the position of children can be appropriately estimated using this technique. © 2012 IEEE.

Asano D.,Shinshu University | Kuroyanagi D.,SCSK | Suzuki H.,Shinshu University | Motoyama E.,Nagano Japan Radio Co. | Fuwa Y.,Shinshu University
IEICE Transactions on Communications | Year: 2014

Landslides during heavy rainfall cause a great amount of damage in terms of both property and human life. To predict landslide disasters, we designed and implemented a wireless sensor network using our existing highly fault tolerant ad-hoc network. Since many sensors must be used, we propose a new MAC protocol that allows the network to support more sensor terminals. Our protocol is a hybrid CSMA/Psuedo-TDMA scheme which allows the terminals to decide their transmission timing independently in a random fashion. A timing beacon is not required, so power consumption can be reduced. Simulation results show that the number of terminals supported by the network can be greatly increased. © 2014 The Institute of Electronics, Information and Communication Engineers.

Ryukawa T.,Niigata University | Yamada H.,Niigata University | Yamaguchi Y.,Niigata University | Hirano K.,Nagano Japan Radio Co. | Ito H.,Nagano Japan Radio Co.
IEEE iWEM 2014 - IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition | Year: 2014

Ocean surface current radar has attracted attention as a system which can be observed ocean phenomenon effectively. In this report, we evaluate the aperture enhancement effect by applying the Khatri-Rao (KR) product array to the Doppler frequency and angular resolution. Since Doppler frequency represents surface current velocity, resolution enhancement leads to estimation accuracy improvement of the velocity. In this paper, we apply the KR product to actual data set of the ocean surface current radar, and estimated surface current velocity. © 2014 IEEE.

Yamada H.,Niigata University | Ozawa N.,Niigata University | Yamaguchi Y.,Niigata University | Hirano K.,Nagano Japan Radio Co. | Ito H.,Nagano Japan Radio Co.
IEICE Transactions on Communications | Year: 2013

Ocean surface current radar is a Doppler radar to observe oceanographic information using the Bragg scattering resonance mechanism. In this paper, we consider angular resolution improvement of the radar. The radar employs an antenna array with FMICW operation, then it can resolve angular distribution by Digital Beam Forming (DBF) and distance by Fourier transform of the beat signal obtained by the FMICW radar. In order to obtain sufficient angular resolution, large array length or aperture with increasing the number of elements is needed, that is often difficult to realize in the HF/VHF ocean surface current radar. In this paper we propose to apply the Khatri-Rao (KR) product array processing to the radar. To verify effectiveness of the KR product array processing in angular resolution enhancement for the ocean surface current radar, we apply the KR product array to actual experimental data set of the radar, and show that the method is available to angular resolution enhancement and Doppler spectrum improvement. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

Murata Y.,KOKUSAI KOGYO CO. | Nagakura T.,KOKUSAI KOGYO CO. | Kokai T.,Nagano Japan Radio Co.
Proceedings of the Coastal Engineering Conference | Year: 2010

HF Oceanographic radar is an equipment, for instantaneously sensing velocity distribution of sea surface current. It has a wide field of view, which extends approximately ±45° in direction and beyond 50km in distance. There are high expectations that the radar observation of Tsunami will become a new road path for preventing disasters. In this paper, we describe a method to enhance the resolutions of radar in both time and current. At first, resolutions required for tsunami observation are estimated by simulating a Tokachi-oki earthquake tsunami (2003). Here it is pointed out that traditional data processing indicates inadequate resolutions for tsunami early detection. Secondly, two techniques are proposed to achieve the necessary resolutions. Short-time Fourier transform (STFT), in place of normal FFT, enhances the time resolution of Doppler analysis. Further, zero-padding technique improves the current resolution, by interpolation of data within the frequency domain. Finally, by means of simulation, it is verified that these proposed techniques give improved resolutions in both time and current.

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