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ISAS/JAXA Tracking station

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). VSOP-2 Ground System (Based on halca method). Freq, Phase Controller. H-Maser. CMD/MON. 100MHz. 10MHz. 1PPS.

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ISAS/JAXA Tracking station

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  1. ISAS/JAXA Tracking station

  2. Usuda Deep Space Center • Diameter 10m • AE 44% expected • Feed & Receiver • Ka-band • Trx < 50K expected • cooled LNA • Tsys 140 K (fine condition)

  3. VSOP-2 Ground System (Based on halca method) Freq, Phase Controller H-Maser CMD/MON 100MHz 10MHz 1PPS Ether GP-IB 7,000MHz 7,000MHz 1100MHz 1,000MHz TX- AMP U/C U/C LO U/C O/E E/O 100MHz 100MHz (±2MHz) 5,900MHz 7,000MHz Freq, Phase Control LO DDS LO 400MHz 37.5 GHz 26,000MHz 40.0 GHz Feed DIP LO 100MHz 100MHz O/E E/O CLK GEN 100MHz (±2MHz) 26,000MHz 400MHz LO 4,500MHz OBS Simulator Freq, Phase Control LO DDS 6,500MHz Carrier track 100MHz 7,000MHz 7,000MHz 500 MHz 500MHz Ether LNA D/C E/O O/E D/C DEM PD Cooled VSI-H FMT Mark5B Network 1PPS Ether Software Spectro- scope PC FIFO Antenna Room Operation Center

  4. VSOP-2 Ground System (w/o Doppler Comp.) Freq, Phase Controller H-Maser CMD/MON 100MHz 10MHz 1PPS Ether GP-IB 7,000MHz TX- AMP 7,000MHz U/C LO O/E E/O 100MHz 7,000MHz LO 37.5 GHz 26,000MHz 40.0 GHz Feed DIP LO 100MHz O/E E/O 26,000MHz LO 4,500MHz OBS Simulator LO 6,500MHz 100MHz 7,000MHz 7,000MHz 500 MHz 500MHz Ether LNA D/C E/O O/E D/C DEM PD Cooled VSI-H FMT Mark5B Network 1PPS Ether Software Spectro- scope PC FIFO Antenna Room Operation Center

  5. Doppler compensation needed? • Related Matters • Band mismatch • PLL Loop stress • Phase characteristics of onboard instruments • Correlator capability • System construction cost

  6. Band mismatch • Doppler shift: ~1MHz (f=40GHz, rr=7km/s) • Band-mismatch: 126 MHz (128 – 2 MHz) • Degradation of SNR ： 0.99 (√126/ 128)

  7. PLL Loop stress • Relation between Doppler rate and PLL : 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.)

  8. 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

  9. 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* correlator Mark5, K5, VERA terminal *EAVN (East Asia VLBI Network)

  10. 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

  11. 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.

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