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A Study on the Portable Space Optical Communication System for Disaster Communications
Keiichi YANO,Yoshihisa TAKAYAMA,Hiroo KUNIMORI,Koichi GYODA 대한전자공학회 2015 ITC-CSCC :International Technical Conference on Ci Vol.2015 No.6
An examination is made to simplify the existing optical transmitter and receiver for the realization of the portable space optical communication system. In the proposed system, a high-precision tracking mechanism of the receiver is reduced for the simplification. In addition, pointing is performed based on the GPS location information to reduce the optical beacons capture mechanism. Both irradiation angle error of atmospheric propagated laser and positioning error of GPS are executed, and the data transmission speed is derived from the estimated result of the diameter of the photodetector which can include these errors.
Comparison of Three Magnet Array-type Rotors in Surface Permanent Magnet-type Vernier Motor
Kataoka, Yasuhiro,Takayama, Masakazu,Matsushima, Yoshitarou,Anazawa, Yoshihisa Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.1
Surface permanent magnet-type vernier motors with three magnet array-type rotors (parallel magnetized type, repulsion type, and Halbach type) are compared based on the pull-out torque. It was clarified that increasing the rotor radius increases the pull-out torque at a fixed three-phase alternating voltage. The mechanism for the pull-out torque increase on each magnet array type was different, when the effects of the increase were analyzed based on an induced electromotive force and a synchronous reactance. As a result, the design of the Halbach-type rotor was found to be especially effective for achieving high pull-out torque, because this array type achieves a large induced electromotive force $E_0$ and a small synchronous reactance $x_s$.
Reconfigurable Communication Satellite System "SoftSAT"
Nishinaga, Nozomu,Ogawa, Yasuo,Takayama, Yoshihisa,Takahashi, Takashi,Kubooka, Toshihiro,Hiroaki, Umehara Hanako 통신위성우주산업연구회 2002 Joint Conference on Satellite Communications Vol.2002 No.-
Satellite communications provides characteristics such as wide-area coverage and flexibility of network construction. Since an enormous budget and time are require for satellite development, however, it is difficult to implement the latest techniques onboard. Even of the latest communications technology is implemented at the time of launch, it is impossible to follow paradigm shifts in terrestrial network technology. In this paper, we propose a reconfigurable communication satellite system based on the formation-flight technique and inter-satellite communication technology. This satellite system consists of a group of layered satellites that can operate together like one satellite.
Design of Surface Permanent Magnet-type Vernier Motor
Kakihata, Hironori,Kataoka, Yasuhiro,Takayama, Masakazu,Matsushima, Yoshitarou,Anazawa, Yoshihisa Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.2
In this paper, the authors designed a surface permanent magnet (SPM)-type vernier motor whose maximum output is more than 5.2 kW, whose power factor at 4 kW is more than 90%, and whose efficiency at 4 kW is 85% under the conditions that the operating voltage, frequency, and synchronous speed are 400 V, 50 Hz, and 100 min-1, respectively.
Measurement of atmospheric turbulence in a ground-to-low earth orbit optical link
Toyoshima, Morio,Kunimori, Hiroo,Jono, Takashi,Takayama, Yoshihisa,Arai, Katsuyoshi 통신위성우주산업연구회 2006 Joint Conference on Satellite Communications Vol.2006 No.-
Ground-to-satellite laser communication experiments between the optical ground station located in the Koganei ward of downtown Tokyo and the low earth orbit (LEO) satellite, Optical Inter-orbit Communications Engineering Test Satellite (OICETS), also known as "Kirari", were conducted in March and May, 2006. Optical communication links through the atmosphere are affected by the refractive index fluctuation in the atmosphere, making measurement and evaluation of atmospheric turbulence crucial issues. The Differential Image Motion Monitor (DIMM) method was used to estimate atmospheric coherence length, hence the seeing size as well, on the ground to satellite optical link. In the DIMM method, several beam spots are formed on the CCD, and the relative motions between the beam spots are calculated as the relative variance of the centers of the spots, which protects the telescope from the effects of vibrational noise and tracking error of the satellite. In contrast to stellar observation, an additional turbulence factor due to the fast movement of the telescope must be considered for ground to satellite optical links. We present the results of our measurements of atmospheric turbulence and estimate the parameters of the analytical model based on those measurements.