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ASTRO-GGround 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
LNA ANT
A/D
MODTX
HGA
RXLOCAL
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 CorrectionCW
14.2 GH zQPSK
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
Number of Tracking stations
Trac
king
tim
e (%
)
FAKESAT for VSOP-2
D.W.MurphyLinux/Cygwin
○Kaj Wiik,R.Dodson
Visibility of HALCA from tracking stations (ah=21,000km, i=31)
ω= 270
ω= 0
ω= 90
ω= 180
SANTMALIHARTUSUDTIDBMADRGOLDGBANK
NorthApogee
SouthApogee
Visibility of ASTRO-G from tracking stations (ah=25,000km)
ω= 270
ω= 0
ω= 90
ω= 180
SANTMALIHARTUSUDTIDBMADRGOLDGBANK
Visibility of ASTRO-G from tracking stations (ah=36,000km, i=28)
ω= 270
ω= 0
ω= 90
ω= 180
SANTMALIHARTUSUDTIDBMADRGOLDGBANK
Tracking station coverage requirements
• 3-4 tracking stations• Uniform Longitude coverage• Low Latitude is better