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WINDS is equipped with a switch matrix (SWMTX) composed of many 4 GHz band analog switches. WINDS switches reception beam/transmission beam connection combinations at a specic interval (2 milliseconds).Synchronization of the onboard SWMTX and high-speed burst modem is maintained by a 155 Mbit/s reference burst (JRB) generated by a JAXA ground terminal. is JRB is 155 Mbit/s, QPSK, which is used for a regenerative transponder, and its error-correcting code is RS (255, 223). One of the NICT terminals transmits the reference burst (Winds RB: WRB) for a 622 Mbit/s bent-pipe transponder that is synchronized with the received JRB. e other earth terminals use only 622 Mbit/s WRB to synchronize with the SWMTX. e JRB carries slot allocation information of regenerative TDMA, and WRB carries slot allocation information for 622/1,244 Mbit/sTDMA. e frame con-guration of TDMA is shown in Fig.　2.e transmission timing of WRB and data burst are corrected to synchronize with the SWMTX by calculating the propagation delay time from the information on the positions of the satellite and earth terminals. e slot length of TDMA is 2 ms, including the guard time of 75 µs.One frame consists of 20 slots, and one super-frame consists of 16 frames. e multi-beam antenna (MBA) is capable of receiving a maximum of eight beams. JRB and WRB are deployed at the front edge of the frame and are capable of transmitting signals in response to communica-tion beams.2.2Satellite transponder and earth terminale onboard transponder of WINDS consists of two MBAs with an antenna aperture of 2.4m, an active phased array antenna (APAA: 128 pixels for both receiver and transmitter), a Tx/Rx-IF switch matrix (IF-SWMTX), an FiF1　High speed satellite TDMA communicationMODEM-1MODEM-2(Slave)PC-1PC-2WRB/DataData622/1244Mbit/s622/1244Mbit/sJRBReference Station(JAXA)LETSDR-VSATJRBreceiverSatellite position,slot assign info., etc.Synchronous signal(Master)FiF2　TDMA frame format Frame 1012345678910111213141516171819Frame 22021222324252627282930313233343536373839Frame 34041424344454647484950515253545556575859Frame 16300301302303304305306307308309310311312313314315316317318319Super Frame40ms2msGuard Time >75μsData Slot WRBJRBTabT1　Satellite payloadOrbitGEO (143 degrees East)MassApproximately 2,700 kg (In Orbit)Size2 m × 3 m × 8 m(solar array paddles deployed: 21.5 m)Design Life5 years (targeted life)PowerMore than 5,200 WAttitude Control3-axis stabilizedFrequency Band18.25 GHz / 28.05 GHz (1.1 GHz BW)AntennaMBA: Two dish of 2.4 m diameter APAA: 128 elements each TX and RXEIRPMBA: more than 68 dBW APAA: more than 55 dBWG/TMBA: more than 18 dB/K APAA: more than 7 dB/KCommunication ModeRegenerative switch by ABS & IFS and Bent-pipe relay with IFSService AreaMBA: Japan and 10 Asian cities APAA: Asia and Pacific areaLaunch VehicleH-IIALaunch DateFebruary 23, 20083 Ultra-High-Speed Satellite Communication Technology102　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)