ISAS/JAXA Tracking station

Usuda Deep Space Center

• Diameter 10m– AE 44% expected

• Feed & Receiver – Ka-band

• Trx < 50K expected– cooled LNA– Tsys 140 K (fine condition)

Feed DIP

TX-AMP

U/C

D/CLNA

H-Maser

DDS

O/E E/O

E/O O/E

LO O/E E/O

U/C

DDS

LO

D/C

LO

DEM PD

FMT

CLK GEN

LO

LO

Mark5B

Cooled

VSOP-2 Ground System (Based on halca method)

PC

OBSSimulator

CMD/MON Freq, PhaseController

40.0GHz

37.5GHz

100MHz(±2MHz)

100MHz

1100MHz

100MHz(±2MHz)

500MHz

5,900MHz

7,000MHz

26,000MHz

4,500MHz

7,000MHz

7,000MHz 7,000MHz

6,500MHz

100MHz

100MHz

500MHz

100MHz 10MHz

VSI-H

1PPS

1PPS

100MHz

400MHz

400MHz

Freq, PhaseControl

26,000MHz

Software Spectro-scope

Ether

Freq, PhaseControl

Network

Ether

7,000MHz

Ether GP-IB

Antenna Room Operation Center

U/C1,000MHz

LO

FIFO

Carriertrack

Feed DIP

TX-AMP

U/C

D/CLNA

H-Maser

O/E E/O

E/O O/E

LO O/E E/O

LO

D/C DEM PD

FMT

LO

LO

Mark5B

Cooled

VSOP-2 Ground System (w/o Doppler Comp.)

PC

OBSSimulator

CMD/MON Freq, PhaseController

40.0GHz

37.5GHz

100MHz

500MHz

7,000MHz

26,000MHz

4,500MHz

7,000MHz

7,000MHz

7,000MHz

6,500MHz

100MHz

100MHz

500MHz

100MHz 10MHz

VSI-H

1PPS

1PPS

26,000MHz

Software Spectro-scope

Ether

Network

Ether

7,000MHz

Ether GP-IB

Antenna Room Operation Center

LO

FIFO

Doppler compensation needed?

• Related Matters– Band mismatch– PLL Loop stress– Phase characteristics of onboard instruments– Correlator capability– System construction cost

Band mismatch

• Doppler shift: ~1MHz (f=40GHz, rr=7km/s)

• Band-mismatch: 126 MHz (128 – 2 MHz)

• Degradation of SNR ： 0.99 (√126/ 128)

PLL Loop stress• Relation between Doppler rate and PLL

thresholderr

Ln

thresholderrn

err

B

,

,2

)2(

: Natural angular frequency of second order loop(rad/sec)

: Rate of change of angular frequency (rad/sec2)

: Phase error of Phase Lock Loop, threshold ( ~12deg.)

HzBL 100

Phase characteristics of instruments

• Phase fluctuation dφ by df :

• Easy estimation – Hup(f)- Hdown(f)=2πfτ– Group delay characteristicsτ: ～ 1nsec– Phase fluctuation dφ ～ 0.36 deg (df~1MHz)

• Phase characteristics measurements needed before launch

2

df)(fHdf)(fH - df)H(f d downdownupup

up

Data Storage• Storage Terminal with VSI

– Mark5B (Haystack)– K5-VSI (NiCT)– Clock fluctuation compensated by FIFO?

• Corrlator interface– VLBA correlator Mark5– ENV correlator Mark5– EAVN* correlatorMark5, K5, VERA terminal*EAVN (East Asia VLBI Network)

East Asia VLBI Network Correlator

• Korea-Japan Joint VLBI Correlator (KJJVC)– KVN and NAOJ

• KVN, VERA, JVN, VSOP-2• Seoul• 16 stations• Data buffer• Data rate

– Max. 8 Gbps/st

Summary

• UDSC 10m antenna is expected to VSOP-2 GTS

• Doppler compensation system depends on cost.

• Several VSI storages are available – Mark5B is better

• for operational easiness at three correlators.