Geodetic VLBI activities in China Fengchun Shu Shanghai Astronomical Observatory, CAS Dec. 5, 2012, Saint-Petersburg

Outline Early history of geodetic VLBI in China Related VLBI technique development Shanghai Correlator CDAS digital backend Geodetic VLBI observing program CMONOC project IVS sessions Outlook for the future development

Early history of geodetic VLBI in China 1985&1986 Shanghai(6m)—Kashima(26m) (X-band only) geodetic VLBI experiments April, 1988 Seshan25 began to participate in international geodetic VLBI experiments, such as: CDP and DOSE/NASA Chinese-Japanese Joint VLBI Experiments Chinese-German geodetic VLBI Cooperative Project March, 1994 Nanshan(25m), Urumqi began to participate in international geodetic VLBI experiments

Shanghai-Kashima Geodetic VLBI Experiments(X-band only, 1985/86) Shanghai(6m)

Seshan25 station Installation completed 1987, and became operational since 1988

First Geodetic VLBI Experiment of Seshan25 S/X-band 1988-4-9 Gilcreek Kashima Sheshan Kauai

Urumqi station - Nanshan 25m antenna Opening Ceremony was held in October 1994

First Geodetic VLBI Experiment of Urumqi 1994-3-16 Gilcreek Nanshan Kokee Sheshan DSS45

Outline Early history of geodetic VLBI in China Related VLBI technique development Shanghai Correlator CDAS Geodetic VLBI observing program CMONOC project IVS sessions Outlook for future development

Shanghai Correlator Operational for ChangE-1 Lunar project since 2006 Hardware platform SMP (Symmetric Multiple Processor) commercial PC server Software platform: Linux Operation System Correlation speed: 40Mbps/station, 4 stations Special correlation ability Data latency < 3 min Fast fringe search and satellite delay model reconstruction

Specifications of Shanghai correlator Architecture station based FX type Correlation station number 1~4 IF number 1~16 Frequency channel 32~4096/IF Integration period 0.1~60 second Input data format Mark5A Output data format CVN Fringe search 2-4 stations Correlation speed 40Mbps/station (4 stations, 1024/IF) Data latency < 3 minutes PCAL detection Yes

Block diagram NFS: Network File System

Shanghai correlator upgrade for geodesy correlator control system SKED/SCHED/SATSKD interface Scan-based processing MK5B playback capability observable extraction flag, fringe fit, manual phase calibration, bandwidth synthesis, NGS format output Graphic display, data quality statistic

Software architecture

Correlation system hardware

New platform for correlation Blade Cluster 6 x Blade Server Blade Configuration: 2xIntel Xeon 5570 (2.93G), 12G DDR3 Memory, 10GbE NIC with TOE && RDMA Storage 3x10TB Raid,10GbE NIC

MARK5 system Mark5 data playback 30 disk modules, 8TBytes

Performance evaluation of the correlator 3 stations: ~800Mbps 5 stations: ~400Mbps 10 stations: ~140Mbps

CDAS development 2007/6: the project initiated, meeting the requirement from 2 new VLBI stations (Kunming+ Beijing) 2010/4: deployment of 16 channels CDAS at 4 Chinese stations 2010/7: CDAS+MK5B(+)+eVLBI setup for satellite tracking 2010/8: Seshan25 participated in IVS-R1445 with the use of CDAS, the project concluded

Diagram of CDAS

CDAS 16 channels Platform (digital part) 4 IFs input 512MHz/IF 16 channels output VSI-H interface 1/2 bit output

CDAS Poly-Phase Platform 1 U Box One main Board 2x512Mhz IF input 1x16x32MHz output with VSI-H 2x16x32MHz output with 10GE (in developing)

Outline Early history of geodetic VLBI in China Related VLBI technique development Shanghai Correlator CDAS Geodetic VLBI observing program CMONOC project IVS sessions Outlook for future development

CMONOC project the National Key Scientific Infrastructure Project --- Crustal Movement Observation Network of China CMONOC-1 CMONOC-2 Construction period 1998～2000 2008～2010 Permanent GNSS stations 27 260 Other GNSS sites 1000 2000 SLR stations 5 7 Domestic VLBI obs. No 8 sessions/year

CMONOC-2: fiducial network stations

CMONOC-2: regional network stations

Goals of VLBI in CMONOC-2 Establishing an operational geodetic VLBI observing system Full functional system Full compatible with international VLBI community Operational in stand-alone mode with Chinese domestic stations Routine service with product quality data Performing regular geodetic VLBI observations Connection between global reference frame and Chinese regional network.

Chinese geodetic VLBI observing system

Distribution of Chinese VLBI Network

Geodetic observations for CMONOC project Observing mode 128(data rate)-8(channel)-1(bit) 256-16-1 Observing sources ~35 sources from ~80 ~65 sources from ~100 Observing sessions 6~12 on annual basis Lower priority than satellite tracking/IVS/EVN sessions

Geodetic observations in IVS R1、RDV、INT3 Participated with Seshan25 only Participate in IVS-INT3 sessions as a backup station since April 2011 300Mbps to Bonn Correlator via Tein3 circuit T2、APSG Participated with Seshan25, Kunming and Urumqi

Kunming station January, 2011 July, 2011 Began to participate in the domestic geodetic observations with the use of CDAS July, 2011 Began to participate in IVS-T2 and IVS-APSG sessions with CDAS To get more precise station coordinates on global scale. To further validate the performance of CDAS in geodetic observations.

Urumqi station New S/X feed installed at Urumqi with wider frequency coverage: 8.0～9.0GHz Ready to participate in IVS-R1/R4 sessions next year

Outline Early history of geodetic VLBI in China Related VLBI technique development Shanghai Correlator CDAS Geodetic VLBI observing program CMONOC project IVS sessions Outlook for future development

CDAS future development Performance improvement on 32MHz bandwidth based on geodetic test obs. Better delay alignment among different BBC channels Better Field System support VDIF interface

Shanghai Correlator short term Mid-term Long term Support the operation of CVN Support the application of CVN in satellite tracking and radio astrometry Mid-term Improve e-VLBI capability of Chinese stations participating in international VLBI Provide domestic geodetic results to IVS data center Support data correlation of specific IVS sessions Long term Support data correlation of VLBI2010 observing sessions

VGOS - VLBI2010 Global Observing System Plans have been put forward to construct at least 2 antennas in China, meeting the requirement of IVS2010. A few candidate sites have been identified. Collocated with SLR technique Less RFI Better sites distribution from global view

Candidate GGOS sites

Thank you!

NEW Receivers (2012)

Seshan25 station April, 2010 April, 2011 VLBA4 analog system was upgraded with VSI interface CDAS was installed for the domestic observations Mark5B+ recorder April, 2011 Participate in IVS-INT3 sessions as a backup station 300Mbps to Bonn Correlator via Tein3 circuit Contribution more to IVS by rapid UT1 measurement

Chinese VLBI sites in ITRF C- Name---- --DOMES-- CDP- Comments/description cc nnnnnnnn ssssstmmm mmmm --------------------------- Km KUNMING 21609S003 7367 40-m antenna at Kunming Sg SHANGHAI 21605S008 7226 6-m at Shanghai Sh SESHAN25 21605S009 7227 Shanghai Ur URUMQI 21612S001 7330 Urumqi

IVS UT1 intensive observing stations