Tokyo, December 10, 2020 - NEC Corporation (NEC; TSE: 6701) today announced the development of laser communications terminals (LCTs) for satellites that use laser light to deliver broadband data transmission in outer space. This terminal has been provided for the Laser Utilizing Communication System (LUCAS) being coordinated by the Japan Aerospace Exploration Agency (JAXA) (*1). Two types of LCT were developed, featuring one for geostationary (GEO) satellites and the others for low earth orbiting (LEO) observation satellites.

In order to commercialize ultra-long-haul laser communications over a distance of 40,000km between GEO and LEO satellites, NEC developed technologies for stably amplifying low-output semiconductor laser light (wavelength@1.5μm) to high output under a vacuum environment, which is ideal for use in submarine cables and LANs, as well as technologies for locating and tracking moving communication partner satellites with high accuracy, and technologies for re-generating broadband signals from very weak light.

In particular, LCTs have been designed to withstand severe vibrations, shocks and radiation - both during launch and while in orbit - and have been designed to dissipate heat generated by laser oscillation adequately. As a result, the newly developed LCT has a transmission rate of 1.8Gbps between satellites, which is more than seven times faster than existing equipment.

NEC's LCT for GEO satellites (*2) is boarded on the optical data relay satellite that JAXA launched from Tanegashima Space Center on November 29, 2020. Moreover, NEC's LCTs for LEO satellites (*3) will be boarded on JAXA's Advanced Land-Observing Satellites, the 3rd DAICHI-3 (ALOS-3) and 4th DAICHI-4 (ALOS-4), which will be launched in the future, when broadband laser communications will be demonstrated and utilized with LUCAS.

LEO satellites directly transmit data to ground stations. Until now, satellites have only been able to transmit to the Earth's surface for approximately 10 minutes during each orbit. A mechanism has been constructed to send data from LEO satellites to ground stations via data relay satellites in GEO, enabling data transmission to be maintained for approximately half of the time for one orbit around the Earth (about 90 minutes), ensuring data transmission time of more than four times (more than 40 minutes) that of the direct transmit system. Conventional data relay satellites that use radio waves have a transmission speed of 240Mbps, even when a few meters in diameter antenna is mounted on a satellite. The LCT has a very small antenna diameter of 14cm, which is about 1/30 that of conventional systems, and the transmission rate between satellites has been increased to 1.8Gbps, 7 times faster than conventional data relay systems.

Due to the expansion of data transmission time and higher bandwidth, more data can be obtained in real time than before, and satellite utilization is expected to advance in various fields.

"NEC has accumulated a wealth of experience in information and communications technology since its establishment in 1899, including a half-century in the development of satellite systems and satellite-mounted mission equipment (*4)," said Hiroaki Miyoshi, Deputy General Manager, Space Systems Division, NEC Corporation. "The innovation of space laser communication technology, which is used in submarine cables to connect regions across the world's oceans, with space environmental technology is resulting in the development of advanced new communications products," he added.

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Reference material:

NEC Space Systems
https://www.nec.com/en/global/solutions/space/index.html

Reaching for the stars
https://www.nec.com/en/global/ad/cosmos/index.html

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