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

Tra

ckin

g ti

me

(%)

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