ASTRO-G Ground Tracking Station Plan Y.Murata (JAXA) Start from HALCA design Functions –Uplink reference signal –Data demodulation –Data recording –Telemetry Data Extraction –Doppler measurement

Signal from Astronomical Objects Orbit Prediction VSOP tracking station H maser Uplink Freq. Cntl. Downlink Freq. Cntl. D/C LNAANT A/D MOD TX HGA RX LOCAL VLBI data SYNC (4byte) DEMOD 2way phase residual 2way Doppler TLM Header (8byte) VLBI data 32M clock 1PPS gen. 1 PPS VLBI Recording TLM ground １５．３ GH ｚ＋ Doppler Correction CW １４．２ GH ｚ QPSK 1 Frame (10,000 byte / 5 ms)

Difference from HALCA tracking station Frequencies – Up: 40 GHz + Doppler Compensation(?) –Down: 37 – 38 GHz Data demodulation –1 Gbps QPSK Data recording –Giga-bit recording, VSI (VERA, Mark 5, K5/VSI, …) Telemetry Data Extraction –Realtime / near realtime Doppler measurement No Phase cal pulse

Number of Tracking stations

Tracking time (%)

FAKESAT for VSOP-2 D.W.Murphy Linux/Cygwin ○ Kaj Wiik,R.Dodson

Visibility of HALCA from tracking stations (ah=21,000km, i=31) ω= 270 ω= 0 ω= 90 ω= 180 SANT MALI HART USUD TIDB MADR GOLD GBANK North Apogee South Apogee

Visibility of ASTRO-G from tracking stations (ah=25,000km) ω= 270 ω= 0 ω= 90 ω= 180 SANT MALI HART USUD TIDB MADR GOLD GBANK

Visibility of ASTRO-G from tracking stations (ah=36,000km, i=28) ω= 270 ω= 0 ω= 90 ω= 180 SANT MALI HART USUD TIDB MADR GOLD GBANK

Tracking station coverage requirements 3-4 tracking stations Uniform Longitude coverage Low Latitude is better