Naokazu Hamamoto

Satellite Terrestrial Integrated mobile Communication System as a disaster countermeasure

Creating a safer society requires communication methods available during disasters. This need has prompted the start of research and development to build a mobile satellite communication system for the satellite terrestrial common terminal. The system is called STICS (Satellite/Terrestrial Integrated mobile Communication System). A dual communication function that can connect to both the terrestrial system and the satellite system is formed by using a common terminal with a portable, handheld shape. This paper discusses the research and development and the current status of STICS.

Outdoor/indoor propagation experiment for estimation of interference to satellite caused by cellular phone in satellite/terrestrial dual-mode frequency-shared cellular phone system

This paper describes the overview and data analysis of the outdoor/indoor propagation experiment planned to estimate the interference level in hybrid satellite/terrestrial cellular phone system. The system, which is a dual-mode frequency-shared cellular phone system, needs fundamental interference level data in the system feasibility study. This work focuses on the estimation of interference level to satellite caused by the cellular phone using terrestrial link, which varies depending on the location of the cellular phone user. The experimental system using an IMT-2000 cellular phone, a continuous wave (CW) transmitter, and a pseudo satellite (PS) located on top of a 50-m tower which mimics the interference situation of the hybrid cellular phone system. In the experiment, dynamic range of measurement is enhanced and number of cellular phone location is increased compared with our previous fundamental experiment held in 2009. Measurement was carried out at over six-hundred positions of cellular phone in outdoor/indoor locations in the office building site. Measured transmit powers of cellular phone and received powers of CW at the PS as well as the estimated received powers of cellular phone transmit wave at the PS are analyzed to extract the difference of trend between outdoor/indoor locations. Analysis of the estimated received power of cellular phone transmit wave at the PS indicates that the estimated PS received power of indoor cellular phone transmit wave is lower than that of outdoor cellular phone transmit wave (differences of average and median values are 8dB and 10dB, respectively). These results are useful in the estimation of the interference level to satellite caused by cellular phone using terrestrial link in the hybrid cellular phone system.

DESIGN AND PROTOTYPE OF SATELLITE TRACK WITH QUADRANT DETECTOR FOR AMBULANCES

Tokai University has been conducting research on ambulances and related onboard systems for transmitting video images from vehicles in motion via the quasi-zenith satellite and HEO, which are scheduled to be launched by the Communications Research Laboratory (CRL) and the National Aerospace Laboratory (NAL). This paper describes a newly-developed high-precision satellite tracking system, which we have developed for use with this system. The core of this tracking system comprises a few mutually complementing independent signal processing subsystems. Within this system, the absolute coordinates of the satellite are estimated by a quadrant detector, while its relative coordinates are estimated by a GPS-based continuous kinematic positioning technique that relies on directional data provided by a fiber-optic 3D gyro and calculations of six orbit elements. The newly-developed technique, which employs coaxial non-backlash gears for high- precision mechanical control and absorbs vibrations generated during vehicle operation with an air cushion installed in the basement of the antenna, can track the satellite with a tracking error of one degree or less as the ambulances move over paved streets. 1.Objective

Measurement experiment of deployable large scale reflector antenna with DBF using A-METLAB

Space base large scale deployable antenna is common element technologies for space development. It will be used not only communication but also observation satellite or solar power satellite. Now, we proposed new satellite communication system called STICS (Satellite/Terrestrial Integrated mobile Communication System) by using large-scale deployable antenna (LDR) of 30m class in the gestational orbit. It has dual communication function that can be connected with both the terrestrial system and the satellite system is composed by using the common terminal with a handheld shape. This communication system will be especially useful for the emergency disaster. For small scale model of STICS satellite beam former and digital bent pipe system, NICT developed 16-element feeding antenna with Digital Beam Former and Channelizer for flexible usage of frequency. To the realistic demonstration, we are now measuring 16-elements DBF with large scale deployable reflector (3.3m Diameter). In this measurement we used A-METLAB (Advanced Microwave Energy Transmission LABoratory) and Plane Polar Near Field Measurement system in Kyoto University. We will introduce preliminary result of this experiment.

A study of an optical profile for the prediction of satellite mobile communication channel to support telemedicine on route

We are aiming to create an optical profile to support mobile e-Health and to confirm the merits of the High inclined Earth Orbiter in the nation wide. This paper deals with actual optical data in the urban and sub-urban area in Japan captured with Fisheye camera, and 6 Hi-vision cameras. Also the data of the receiving power density on S band of the mobile satellite(GEO) obtained, and we show the analysis of the both data(optical and radio), and its models to predict propagation from the land mobile satellite service(LMSS). This optical study was well done. The result of comparing with ITU-R simulation might be acceptable to predict the satellite propagation of the line of sight in urban area. We intend to study more using with ETS-VIII the next generation mobile communications satellite with NICT.