TOMIKI ATSUSHI

Balloon Symposium 2016 (November 1-2, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan

16th Space Science Symposium (January 6-7, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan

A high-speed downlink communication system is required to meet various applications for nano/small satellites. Therefore, it is essential to implement a transmitter with small weight and power in such satellites. We have developed high speed communication system over 300 Mbps for small satellite. In order to reduce DC power consumption of transmitter, we have developed GaN-HEMT power amplifier for X band downlink. The Hodoyoshi-4 satellite equipped with the developed communication system was launched in 2014 and we demonstrated 348 Mbps downlink from 50-kg class satellite. This paper describes the summary of the developed system, the experiment of high speed downlink, and future works.

A high-speed downlink communication system is required to meet various applications for nano/small satellites. Therefore, it is essential to implement a transmitter with small weight and power in such satellites. We have developed high speed communication system over 300 Mbps for small satellite. In order to reduce DC power consumption of transmitter, we have developed GaN-HEMT power amplifier for X band downlink. The Hodoyoshi-4 satellite equipped with the developed communication system was launched in 2014 and we demonstrated 348 Mbps downlink from 50-kg class satellite. This paper describes the summary of the developed system, the experiment of high speed downlink, and future works.

This report described measurements and characterization of ultra-wideband (UWB) radio propagation within a small scientific satellite and simulation of transmission performance based on propagation measurements, with a view to (at least partly) replacing wired on-board data buses with wireless communications. Adoption of wireless technologies within spacecrafts could contribute to (i) reduction of cable weight and resulting launching cost, (ii) reduction in the cost of manufacture and test, (iii) ensuring reliable robust communication due to effect of route diversity, (iv) more flexibility in layout of subsystems, and (v) more reliable connection at rotary, moving, and sliding joints. However, narrowband wireless communication systems yield dead spot and intersymbol interference (ISI) due to multipath propagation, particularly in metal-enclosed spaces such as inside of satellites. To apply wireless communication within satellites, a combination of UWB and orthogonal frequency division multiplexing (OFDM) overcomes the dead spots and ISI. Bit error rate (BER) performance of the UWB-OFDM wireless transmission was evaluated through simulation using measured propagation data. Simulation results revealed that the system attained BER ≦ 10^<-5> at 400 Mb/s in all measurement points while ensuring a margin of approximately 15 dB to -41.25-dBm/MHz equivalent isotropic radiated power.