A plan for real-time monitoring of the earth orientation parameters using the Internet VLBI

Transcription

1 EGS /4/25 A plan for real-time monitoring of the earth orientation parameters using the Internet VLBI T.Kondo, Y.Koyama, J.Nakajima, M.Sekido,, R.Ichikawa, E.Kawai, H.Okubo, H.Osaki, and M. Kimura Communications Research Laboratory Key Technology for Establishing Space-Time Infrastructure in Space QSO Spacecraft Space-time Positioning Standard Coordinates Space-borne Hydrogen Maser Standard Time Keeping of Fiducial Satellites Real-time EOP measurements Keeping Ground Fiducial Points Space lighthouse sattelite (Space-time fiducial point) Time and Frequency Supplying

2 SUN UT1-12h Real-time EOP Monitoring and Spacecraft Positioning Polar Motion Spin Axis Wobble QSO Longitude =0 Spacecraft KSP VLBI network ( ) Around Tokyo Koganei Kashima Miura Japan Tateyama 100km

3 Real-Time VLBI System 256Mbps(=16Mbps 16ch)/station INPUT INTERFACE INPUT INTERFACE KOGANEI KASHIMA MIURA TRANSMITTER 256Mbps TRANSMITTER 256Mbps NETWORK NTT MITAKA CROSS-CONNECT RECEIVER 1Gbps INPUT INTERFACE INPUT INTERFACE TRANSMITTER operation ended in Mbps TATEYAMA TRANSMITTER operation ended in Mbps OC-48 Max 2.4Gbps INPUT INTERFACE CORRELATOR KOGANEI Kashima-Tateyama June 26: Volcanic Activities Began 45mm

4 Demonstartion of Real-time EOP Determination on the KSP Network A ch 1 ch 2 Internet-VLBI for Geodetic Use (Multi channel system) A PC-based VLBI ch 1 ch N B ch 1 B A B ch 2 ch 2 A B ch N Band width synthesis ch N Internet Data Transmission Data Reception Correlation Processing

5 Internet-VLBI System First Fringe on Kashima-Koganei Koganei Baseline PCI Sampler board 16MHz sampling Sept.17, C273B 10sec integration (Note : This is offline processing!) Specifications of Sampler Board Reference signals 10MHz (+10dBm), 1PPS Number of INPUT CH 1 : main board only 4 : with auxiliary board A/D 1, 2, 4, 8 bits Sampling Freq. 40kHz, 100kHz, 200kHz, 500kHz, 1MHz, 2MHz, 4MHz, 8MHz, 16MHz

6 Operation form of Internet VLBI Real-time VLBI Quasi real-time VLBI Station A Station B IP Transmission Correlation Station A Station B Hard Disk Off-line VLBI (ftp-vlbi or e-vlbi) IP Transmission Correlation Station A ftp Correlation Station B Hard Disk Disk volume requirements Off-line VLBI(ftp ftp-vlbi) Station A ftp Correlation Station B Hard Disk 24-hour session scan length : 200 sec number of scans : 300 Data rate 256Mbps (16ch X 16Mbps) 64Mbps (16ch X 4Mbps) 1.92TB 480GB

7 K5 Data Acquisition Terminal K-5 Data Acquisition Terminal (coming soon) 7625A (Reference signal distributor) 7626 (16ch video amps) 7680 (Versatile Scientific Sampling Processor) x 4 Hard disk drive 120GB x 16 = 1.92TB K5 PC-based Data Acquisition Terminal (under consideration) K-5 Data Acquisition Terminal 7625A (Reference signal distributor) 7626 (16ch video amps) 2U rack mount server (with an IP-VLBI board (9260) and removable hard disk drive 120GB x 6) x 4

8 K5 Block Diagram ch Sampler(9260) & PC x 4 Hard Disk Units A/D A/DA/DA/D 120GB x 4 100BASE-TX 1000BASE-T A/D A/DA/DA/D Hub Video Sig In A/D A/DA/DA/D A/D A/DA/DA/D 16 Ref. Sig In 10MHz, 1PPS Ref.Sig Distributor 7625A Characteristics of K5 Terminal Item Reference signals Number of input channels 16 Low pass filter Characteristic Sampling frequency 40kHz, 100kHz, 200kHz, 500kHz 1MHz, 2MHz, 4MHz, 8MHz, 16MHz A/D resolution (bit) 1, 2, 4, 8 Hard disk drives 120GB (minimum)/ch total > 1.92TB Maximum sampled data rate 256Mbps Real-time VLBI 10MHz(+10dBm), 1PPS 4MHz / 8MHz supported Typical operation mode 16ch x 4Mbps 16ch x 8Mbps 16ch x 16Mbps Cost < 40,000 US$ VSI out will be supported

9 K5 PC-based correlator K-5 Correlator Rack mount server with 240GB hard disk drive x 16 Progress in Software Correlation Processing Speed Time required for 1sec integration (sec) Pentium II 300MHz Pentium III 1GHz PV-WAVE C/C++ Pentium IV 2GHz 4MHz Sampling 16 lag

10 Real-time monitoring of Earth Orientation Parameters Sun Spin Axis Wobble QSO UT1-12h Polar Motion Lon=0 Internet EOP Analysis Real-time Correlations Conclusions Internet real-time VLBI sytem to take over current geodetic VLBI system is under development PC-based system for signal sampling and data correlations has been developed Ftp VLBI is possible