Tatsuyuki Hanada

JAXA's efforts toward next generation space data-relay satellite using optical inter-orbit communication technology

JAXA has made an effort to build the next generation space data relay network. The inter-orbit optical links are essential segments for such a network in order to fulfill requirements of high resolution earth observation satellite applications and humaned space flight mission. In this paper, JAXAs R&D activities towards realizing advanced optical communication terminals are introduced. The target of the terminals is to establish the optical data relay link between LEO and GEO up to 2.5 Gbps of data-rate. The space data relay network with the terminals will provide seamless and high rate data downlink service for user spacecrafts in LEO.

Coherent homodyne receiver with a compensator of Doppler shifts for inter orbit optical communication

This paper presents Bread Board Model (BBM) of coherent homodyne receiver with an optical phase locked loop and a frequency compensator of Doppler shifts for inter satellite optical communication link. 2.5Gbps BPSK data has been demodulated with sensitivity of -49.1dBm at bit rate of 1e-6 under initial frequency offset of +/-7 GHz simulated as Doppler shifts due to variation of distance between each satellite.

Homodyne BPSK receiver with Doppler shift compensation for inter satellite optical communication

This paper presents Bread Board Model (BBM) of homodyne BPSK (Binary Phase Shift Keying) receiver with an optical phase locked loop and a Doppler shifts compensator for inter satellite optical communication link. 2.5Gbps BPSK data has been demodulated with sensitivity of −49.1dBm at bit error rate of 1e-6 under initial frequency offset of +/−7.5 GHz simulated as Doppler shifts due to relative motion of each satellite.

Study of optical inter-orbit communication technology for next generation space data-relay satellite

JAXA has made efforts to build the next generation space data relay network. The inter-orbit optical links are essential segments for such a network in order to fulfill requirements of high resolution earth observation satellite applications (such as Advanced Land Observing Satellite (ALOS) follow-on missions by JAXA) and manned space flight missions. JAXAs R&D activities for advanced optical communication terminals are introduced. The target of the terminals is to establish the optical data relay link between the LEO user satellite and the GEO data relay satellite up to 2.5 Gbps of data-rate. JAXA has started the development of a Bread Board Model (BBM) of the terminal in order to evaluate the feasibility of the terminal. The terminal is aimed to be small and light-weighted, which is helpful for an onboard capability of the LEO satellite. Furthermore, the modulation of carrier and the acquisition and tracking sequence are selected in order to achieve the interoperability of optical space communication systems. We recently study the feasibility of the acquisition and tracking sensor, the waveguide high power amplifier for a transmitter and the homodyne coherent receiver etc. in the development of BBM.

R&D status of the next generation optical communication terminals in JAXA

Optical free space communication is a key element of the future data-relay satellite system which supports space activities, especially in the fields of earth observation satellite programmes and manned flight missions. Aiming to realization of small and light-weight onboard optical terminals, JAXA launched research and development activities in 2008. The terminals have capabilities to enable communication links up to 2.5 Gbps between data relay satellites in GEO and LEO earth observation satellites. The target weights of terminals are less than 35 kg for LEO terminal and less than 50 kg for GEO terminal, respectively. In this paper, the current status and outcomes of R&D toward JAXAs next generation optical communication system are reported. The system design of the terminals and studies of critical technologies which are necessary to realize the terminals are performed. As a study of critical technology, a homodyne coherent optical receiver has been developed and successfully operated under Doppler optical carrier shift which is unenviable in GEO-LEO communication links. In addition, JAXAs efforts toward to establish future data relay satellite system are also presented.

Development of acquisition and tracking sensor for next-generation optical inter-satellite communication

Laser-based optical inter-satellite communication equipment enables large capacity communication, which is essential for future observation satellites that handle huge amounts of data. One of the key technologies for optical inter-satellite communication equipment is the rapid, highly accurate acquisition and tracking of the corresponding satellite. Therefore we are developing a prototype of an acquisition and tracking system. Key specifications and experimental results of the sensor for the system are described in this paper.

Optical homodyne BPSK receiver with Doppler shift compensation for LEO-GEO optical communication

This paper presents Bread Board Model (BBM) of homodyne BPSK (Binary Phase Shift Keying) receiver with an optical phase locked loop and a Doppler shifts compensator for inter-satellite optical communication link. 7.2Gbps BPSK data has been demodulated with sensitivity of -43dBm at bit error rate of 1e-6 under initial frequency offset of +/-7.5 GHz simulated as Doppler shifts due to relative motion of each satellite.

Development of acquisition and tracking system for next-generation optical intersatellite communication

One of the key technologies for optical inter-satellite communication equipment is the rapid, highly accurate acquisition and tracking of the corresponding satellite. Therefore, we are developing a prototype of an acquisition and tracking system. This paper describes the specifications and performance test results of the prototype acquisition and tracking system.

Three-year program to improve critical 1-micron Qsw laser technology for Earth observation

Laser remote sensing technologies are valuable for a variety of scientific requirements. These measurement techniques are involved in several earth science areas, including atmospheric chemistry, aerosols and clouds, wind speed and directions, prediction of pollution, oceanic mixed layer depth, vegetation canopy height (biomass), ice sheet, surface topography, and others. Much of these measurements have been performed from the ground to aircraft over the past decades. To improve knowledge of these science areas with transport models (e.g. AGCM), further advances of vertical profile are required. JAXA collaborated with NICT and RIKEN started a new cross-sectional 3-year program to improve a technology readiness of the critical 1-micron wavelengths from 2011. The efficient frequency conversions such as second and third harmonic generation and optical parametric oscillation/generation are applied. A variety of elements are common issues to lidar instruments, which includes heat rejection using high thermal conductivity materials, laser diode life time and reliability, wavelength control, and suppression of contamination control. And the program has invested in several critical areas including advanced laser transmitter technologies to enable science measurements and improvement of knowledge for space-based laser diode arrays, Pockels cells, advanced nonlinear wavelength conversion technology for space-based LIDIRs. Final goal is aim to realize 15 watt class Q-switched pulse laser over 3-year lifetime.

Ka-band High Data Rate Transmission Tests for DRTS follow-on mission

Japan Aerospace Exploration Agency (JAXA) is now under planning on the mission of Data Relay Test Satellite(DRTS) follow-on that named as the DRTS-2 temporarily. The overview of DRTS-2 data relay communication is introduced with the expansion for Kaband higher data rate from DRTS. The Ka-band high data transmission tests are performed and the test results are verified to be able to realize for 800Mbps high data transmission.