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Kobayashi N.,Information Technology R and nter | Misawa M.,Information Technology R and nter
Mitsubishi Electric Advance | Year: 2014

For telematics-compatible in-vehicle information systems, security related requirements and issues were reviewed, and a new system has been proposed to prevent an increase in the processing load on in-vehicle equipment, to ensure long-term security strength, and to keep the security system functioning in case of disrupted communications and other troubles.


Tashima Y.,Japan Aerospace Exploration Agency | Tashima Y.,Japan Atomic Energy Agency | Inaoka K.,Japan Aerospace Exploration Agency | Yajima M.,Japan Aerospace Exploration Agency | And 6 more authors.
33rd AIAA International Communications Satellite Systems Conference and Exhibition, ICSSC 2015 | Year: 2015

The observation capabilities of Earth observing satellites have grown. To increase data transmission speeds, we have investigated a Ka-band data downlink system for Earth observing satellites. One of the most important components of the onboard Ka-band communication subsystem is the RF power amplifier which has the greatest power consumption. Linearization using distortion compensation techniques reduces the amplifier’s output power back-off and enables the utilization of 16-quadrature amplitude modulation (16-QAM) signals, which are more sensitive to linear and non-linear distortion than quadrature phase shift keying signals. This paper describes the performance evaluation of a Ka-band satellite communication subsystem using pre-distortion techniques by both simulation and experiment. It was demonstrated that pre-distortion could reduce the output power back-off of the amplifier by 2.2 dB under the same error vector magnitude of the 16-QAM signal. © 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All Rights Reserved.


Horiguchi K.,Information Technology R and nter | Yamamoto K.,High Frequency and Optical Device Works | Nakayama M.,Information Technology R and nter
Mitsubishi Electric Advance | Year: 2012

We have developed a 3.4-V, 1.95-GHz band stage-bypass power amplifier capable of operating in three power modes. This amplifier switches the signal path to use different transistors and circuit configurations for high, medium and low power modes. The new amplifier satisfies the distortion specifications of the wideband code division multiple access (W-CDMA), while achieving superior performance of power added efficiency (PAE) of 40%, 23% and 12% at high, medium and low power mode, respectively.


Angelov I.,Chalmers University of Technology | Thorsell M.,Chalmers University of Technology | Andersson K.,Chalmers University of Technology | Inoue A.,Information Technology R and nter | And 2 more authors.
IEICE Transactions on Electronics | Year: 2010

The large signal performance and model for GaN FET devices was evaluated with DC, S -parameters, and large signal measurements. The large signal model was extended with bias and temperature dependence of access resistances, modified capacitance and charge equations, as well as breakdown models. The model was implemented in a commercial CAD tool and exhibits good overall accuracy. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.


Fujimura A.,MItsubishi Electric | Fujimura A.,Information Technology R and nter | Tani S.,MItsubishi Electric | Tani S.,Information Technology R and nter | And 6 more authors.
31st AIAA International Communications Satellite Systems Conference, ICSSC 2013 | Year: 2013

A novel DEMUX/MUX method that is compatible with variable bandwidths for digital channelizers has been developed. The proposed method has a tree structure composed of Frequency Converters (FC) and Half Band Filters (HBF) which achieves less hardware complexity and lower over sampling speed. Excellent characteristics have been confirmed by hardware experimentations using the developed engineering model. By utilizing the proposed method to digital channelizes, they can satisfy various satellite communication system requirements such as low power consumption, flexible bandwidth management, onboard modulation and demodulation.

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