Koichi Shin

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.

Characteristics of the FM radio waves propagated over the epicenters

We have gotten the first opportunity to observe characteristics of the FM radio wave propagated over the epicenter. In our observation system installed at Nobeyama, fluctuations of the FM radio wave of 82.3MHz had been observed on the two Niigata Prefecture earthquakes on October 23 in 2004 and on July 16 in 2007. In this paper, the propagation characteristics of FM radio wave are carefully checked for six years. Some EM anomalies of the FM radio waves had been detected before the earthquakes. However, the similar EM anomalies were detected not only before the earthquakes but also the following years. They have good correlated with the refractive index gradient of the atmosphere. Then, these EM anomalies are concluded not due to seismic but meteorological phenomena.