Masahiro Nishi

Human detection system using UHF band terrestrial TV receiving waves

This paper proposed the new human detection system, which remarkably used the indoor multi-path propagation of UHF band TV broadcasting waves. In order to investigate the human detection abilities of the system, the received levels of the UHF band TV waves in the room with or without human presence was measured. From the measurement results, the following subjects were clarified: (a) the proposed system could detect human presence using an appropriate threshold of the received level fluctuation; (b) the detectable area of the system was the whole room; (c) the monitoring time of 7 seconds could realize 100% probability of human detection

Proposal of new information traffic platforms in UHF band for communication and broadcasting services

In the second half of the twentieth century, the technological environments in communication and broadcasting services have been greatly advanced, and the information services (IS) of the next generation are going to be developed towards the twenty first century. The IS will require broadband, mobile and asymmetrical communications. What media will be suitable for the IS in the future information traffic platforms? In this paper, it is considered that the UHF band used in the existent analog terrestrial TV broadcasting will be suitable for the download channel of the new IS. In order to clarify the validity of using the UHF band, the propagation loss is compared between 470 MHz of UHF TV broadcasting and 2 GHz of IMT-2000. Furthermore, since it is necessary to seamlessly provide the IS not only in outdoor but also in indoor environments, the basic radio propagation is measured in indoor environments.

Measurements on UHF radio propagation over the Seto Inland Sea

This paper investigates the characteristics of UHF band radio propagation over the Seto Inland Sea in order to obtain primary data to estimate interferences of the terrestrial digital TV system that will be operated in UHF band. The authors have measured UHF band TV broadcasting waves from the Matsuyama station at two observatories in Hiroshima prefecture since June in 2005. From the measurement data, it was clarified that short-term fading with a duration time less than 1 hour frequently occurred in summer season and that long-term fading related to sea level fluctuations occurred in winter season. It was also found that the received level became stable when the typhoon with strong winds hit the propagation paths.

Measurements of UHF band radio propagation in mobile outdoor environments by use of existent TV broadcasting waves

This paper proposes an original method for UHF band radio propagation measurements by use of existing TV broadcasting waves and describes how to develop a mobile measurement system for UHF band radio propagation in mobile outdoor environments. And the paper shows measurement limitation, frequency selectivity, antenna directivity and temperature characteristics of our developed measurement system. As a result of experiments in UHF band radio propagation, the paper shows the received level contour map of Hiroshima City. This map clarifies that the received level is dependent on the surrounding features.

Observation of co-seismic electromagnetic waves associated with the Geiyo earthquake in 2001

Many observations have been conducted to clarify the relationship between electromagnetic (EM) phenomena and earthquake (EQ) activities. In our observation system, EM waves associated with EQs have been received in the very high frequency (VHF) band. We have newly developed a dual frequency observation method with a highly sensitive synthesized FM tuner. Our observation method can clarify and judge whether a received signal is a broadband EM wave or an FM broadcasting wave. We had the Geiyo EQ (M/sub J/=6.4, d=60 km) and the aftershock of the Geiyo EQ (M/sub J/=5.2, d=50 km) in 2001. Our observation system detected co-seismic broadband EM waves associated with the Geiyo EQ in the VHF band. The observed EM waves reached a peak right after the EQ and slowly returned to a normal level about three hours later. We also describe a new phenomenon: a small fluctuation of about 2 dB occurred about one day before the Geiyo EQ, then, the fluctuation just disappeared at the occurrence of the earthquake.

Digital Signage with Audience Detection Using TV Broadcasting Waves

We propose of a digital signage system with a new audience detection system using TV broadcasting waves and show its experimental trial at our university for about three months. For audience motion detection, we use received level fluctuations of TV broadcasting waves by sensing physical movement. The authors have already developed this detection technique and we applied this as audience detection of digital signage. When our detection method detects human motion, a digital signage system will turned on its display. This flow grabs more attention to the signage display and effectiveness of saving electric power. Through the experimental trial, we show that our detection method provides effectiveness for audience detection of digital signage with a big monitor and we can save the electric power of 60-70% of the signage display and one of 94% in business days and in holidays, respectively.

Observation of Co-seismic Electromagnetic Waves in VHF Band Associated with Earthquakes

We have developed a novel dual frequency method to observe electromagnetic (EM) phenomena associated with earthquakes. Our observation started from 1998, during our observation, co-seismic EM phenomena have been observed on three earthquakes, Tottori-ken-seibu EQ in 2000, Geiyo EQ in 2001 and Ibaraki-ken-oki EQ in 2002. In this paper, we describe our observation method and co-seismic observation results associated with the earthquakes

Measurements on overreach propagation of TV and FM waves from Korea to Japan

In this study, we measured terrestrial TV waves and FM waves from Korea to Japan to investigate overreach interference in digital TV waves. In order to evaluate co-channel interference in the TV waves, we proposed a measurement method that monitored both RSSI (Received Signal Strength Indicator) and CNR (Carrier to Noise power Ratio) of the digital TV waves and RSSI of FM broadcasting waves from several cities at the same time. Based on measurements of TV and FM waves, this study clarified that our proposed method was effective to evaluate the interference from Korea.

Proposal on human detection system around detached house using UHF band transmitters

This paper newly proposes the human detection system around a detached house using UHF band transmitters, for the purpose of crime-prevention on the premises. In Japan, we can easily utilize some licence-free specified low power radio stations as UHF band transmitters, such as transceivers using 400 MHz band and wireless microphone systems using 800 MHz band; they are commercially available systems. In our proposed system, therefore, 400 MHz band or 800 MHz band specified low power radio stations are used as radio transmitters. In general, the shape of premises around detached house is rectangle, and this paper studies one configuration of our proposed human detection system with two transmitters installed at the diagonal corners and two receiving antennas installed at the other diagonal corners. Based on the measurement, this paper evaluates the detection performances of the proposed systems using 400 MHz band and 800 MHz band transmitters. From the measurement results, it is found that both 400 MHz and 800 MHz band system can detect human motion around the detached house and that the detection probabilities are over 80 % in most areas on the premises.

Classification method for reflection and duct propagation of FM radio waves observed at Hiroshima and Aso in Japan

Electromagnetic waves in the FM broadcasting frequency band have been observing at our eleven observatories in Japan. We have been frequently observed anomalous FM radio waves due to reflection by the ionospheric sporadic-E layer, and due to the tropospheric duct propagation. For large amounts of data observed in years, it is important to classify them automatically. Thus, we propose a method to classify above two FM radio waves based on their propagation characteristics. We evaluated the method using data observed at Hiroshima and Aso from 2005 to 2010. As a result, we confirmed that the classification method worked correctly.