VLBI2010 Current status of the TWIN radio telescope project at Wettzell, Germany

Transcription

1 VLBI2010 Current status of the TWIN radio telescope project at Wettzell, Germany Alexander Neidhardt, FESG/TU München (on behalf of the BKG) G. Kronschnabl, (BKG); Hase, H. (BKG); Schreiber, U. (BKG); K. Pausch (Vertex GmbH); W. Göldi (Mirad); B. Petrachenko (NRCan); A. Emrich (Omnisys) and the VLBI team Wettzell 1 The geodetic observatory Wettzell and the current VLBI System 2 1

2 The geodetic observatory Wettzell and ist location Federal Agency for Cartography and Geodesy, Frankfurt See: Download 2010/0217 Technische Universitaet Muenchen Research Group Satellite Geodesy Geodetic Observatory Wettzell Germany surrounded by the Bavarian Forest 3 The geodetic observatory Wettzell and ist location Time& Frequency Radio Telescope Wettzell Ringlaser (Large gyroscope) New gravimetry house Meteo Laser Ranging Telescope GPS Area of the new Twin Radio Telescope Wettzell Gravimetry See: Download 2010/

3 Radio telescope Wettzell (RTW) and its team RT Wettzell/Germany TIGO Concepción/Chile GARS O Higgins/Antarctica The Wettzell VLBI crew (from left to right): Ch. Plötz, E. Bauernfeind, G. Kronschnabl, R. Schatz, W. Schwarz, R. Zeitlhöfler, A. Neidhardt (missing in picture: E. Bielmeier). And in the future: TTW Wettzell RTW: D=20m, S/X-Band; Velocities: 3 & 1.5 /s; Tsys=40K; 1Gbps; 5 Radio telescope Wettzell (RTW) and its team 6 3

4 Radio telescope Wettzell (RTW) and its team 7 Main participation International VLBI Service for Geodesy and Astrometry 8 4

5 VLBI VLBI2010 a vision VLBI 2010 IVS WG 3 VLBI2010: Current and future requirements for geodetic VLBI Systems Goals for a next generation VLBI-System: Determination of the relative position better than 1 mm / year Continuous observation of the Earth Orientation Parameters (EOP) Very fast generation and distribution of IVS-products and results Ł continuous and precise UT1 monitoring for UT1-UTC determination Ł improvement of the Celestial Reference Frame (CRF) Source: IVS WG3 Final Report - ftp://ivscc.gsfc.nasa.gov/pub/annual-reports/2005/pdf/spcl-vlbi2010.pdf 10 5

6 Improvements where: SNR = signal to noise ratio f = VLBI processing factor (ca for 1bit Data streams) S = source-flux (Jy) D i = antenna diameter per Station k = Boltzmann constant e i = beam efficiency of the antenna BR = bit rate t = integration time T sys = system temperature per station (at the same frequency) higher bandwidth better quantization of the signals higher effectivity of the dish higher data acquisition rate reduced system temperature better path lengths behaviour Source: IVS WG3 Final Report 11 New frequency band simulations Phase Standard S/X Bands with a band width of 250 & 720 MHz SNR to resolve the phase BW=1 GHz BW=2 GHz BW=0.5 GHz frequency (GHz) No. of frequency bands Phase Broadband-Sequence with 4 Bands and a band width of 1 GHz Phase delay precision BW=0.5 GHz BW=1 GHz BW=2 GHz frequency (GHz) No. of frequency bands Source: B. Petrachenko: Broadband Delay Tutorial, FRFF Wettzell

7 Basic antenna and system requirement definitions Fast moving antenna (6 /sec) Antenna dish diameter of min. 12m Broadband receiving system (2 to 14 GHz or higher including S- and X-band for compatibility to the current systems; optional Ka-band) 1 mm position and 1 mm/year velocity stability of reference position (stiff construction, new system calibrations) Optimized antenna dish and receiving system efficiency Digital data acquisition systems with high sampling rates and quantization (min. 2 Gbit/sec with 2, 4 and 8 bit) Phase center stability over different frequencies Phase delay measurement systems High mechanical quality for gears, motor servos, bearings, etc. More than one antenna at one site Remote controllable, automatable techniques 13 A complete realization the TWIN radio telescope concept 14 7

8 A complete realization the TWIN radio telescope concept Technical details: Main reflector: 13.2m Ring focal design f/d = 0.29 Path Length Error <0.3mm ALMA Mounting with drive velocities of 12 /s in Azimuth and 6 /s in Elevation Balanced antenna design 27Bit Encoder : resolution Adjustable sub-reflector using a Hexapod Lifetime min. 20 years 15 A complete realization the TWIN radio telescope concept Technical details: Main reflector: 13.2m Ring focal design f/d = 0.29 Path Length Error <0.3mm ALMA Mounting with drive velocities of 12 /s in Azimuth and 6 /s in Elevation Balanced antenna design 27Bit Encoder : resolution Adjustable sub-reflector using a Hexapod Lifetime min. 20 years 16 8

9 A complete realization the TWIN radio telescope concept 17 A complete realization the TWIN radio telescope concept Ground and soil analysis 18 9

10 Location analysis 19 Location analysis BK20 BK18 BK21 BK

11 A complete realization the TWIN radio telescope concept Ring focus design 21 The ring focus design (1) Source: Hase, H.; et. al.: TWIN Telescope Wettzell A VLBI2010 project. FRFF Workshop,

12 The ring focus design (1) Source: Hase, H.; et. al.: TWIN Telescope Wettzell A VLBI2010 project. FRFF Workshop, The ring focus design (2) Distribution of the radiated energy 13.2m Ring Focus Antenna Aperture Field Distribution, f = 5 GHz Relative Amplitude [db] dual-reflector receiving system optimal for large flare angles no blockage by the sub-reflector high illumination efficiency the feed horn is prevented by radiation from the sun rho [m] 24 12

13 The ring focus design (2) Effective beam efficiency Source: Hase, H.; et. al.: TWIN Telescope Wettzell A VLBI2010 project. FRFF Workshop, A complete realization the TWIN radio telescope concept Reduction of deformations 26 13

14 A stable path length (error < 0.3 mm) subreflector (ellipse) P1=P1' P3 focus ellipse P3' L3 focus feed P4 L2 L1 P4' feed cone P2 L4 main reflector P2' P5' P5 elevation axis not deformed deformed L1 = distance main axis to reflector surface L2 = distance reflector surface to sub-reflector L3 = distance sub-reflector to feed focus L4 = distance feed focus to axis intersection point Reduction of the gravitational effects using a hexapod to position the sub-reflector 27 Gravitational deformation Quelle: Vertex Design Review; Dez

15 Wind uploads (40km/h) Wind Wind Wind Quelle: Vertex Design Review; Dez A complete realization the TWIN radio telescope concept Surface accuracy 30 15

16 Surface quality 7 Z-profile supports on the backside Surface error RMS < 65 um Gap between panels < 1mm 31 A complete realization the TWIN radio telescope concept Broadband receiving system 32 16

17 Tri-band corrugated horn (Mirad) S-, X- and Ka-band The planned horns Eleven feed (Omnisys/Chalmers University Goteborg) 2-11 GHz Quelle: Willi Göldi, Mirad; M. Pantaleev, Chalmers Univ.; Schweden 33 Tri-band corrugated horn (Mirad) S-, X- and Ka-band The planned horns Eleven feed (Omnisys/Chalmers University Goteborg) 2-11 GHz Dewar B PF LNA Turnstile X-Ba nd 3dB/90 X/RHCP X/RHCP Horn S-Band Turnstile S-Band Hybrid X/LHCP B PF B PF LNA LNA X/LHCP T FEED, L FEED T LNA, GLNA T next Horn X-Band Ka/RHCP Ka/RHCP T ANT Feed Ka-Band LNA Septum Polarizer Ka/LHCP Ka/LHCP B PF 3dB/90 Hybrid S/RHCP S/LHCP B PF LNA LNA S/RHCP S/LHCP T, L optic optic T8 port, L8 port B PF Quelle: Willi Göldi, Mirad; M. Pantaleev, Chalmers Univ.; Schweden 34 17

18 Cryogenic dewar for the Eleven feed (Omnisys/Chalmers University Goteborg) Quelle: A. Emrich; Omnisys.; Schweden 35 The whole receiving system Phase-Calibrationsystem Other channels 5/10 MHz- Distributor Phasetrack -Cable H-Maser Feed/Dewar LNA s MW-Filter 0-14 GHz VPol HPol Amp MW-Mixer Synthesizer GHz MW-Filter MW-Filter 20-22GHz Amp MW-Mixer PLDRO 22.5 GHz Amp MW-Kabel DAQ-System DBBC, DBE MK5B, MK5C A/D MK5 MW-Filter 0-14 GHz Amp MW-Filter 20-22GHz Amp Amp MW-Kabel MW-Mixer MW-Mixer Subreflectorhorn NoiseCal Injection MW-Filter Controller RMS-Detector FS-PC 36 18

19 Cable wrap optimized for cable delay stability and used space 37 A complete realization the TWIN radio telescope concept Remote control and unattended observations 38 19

20 The new observation strategies in a new operator room Internet Internet Local Remote Shared Unattended RTW TTW1 TTW2 OHIGGINS TIGO SOSW WLRS Data center 39 The TWIN radio telescope some impressions 40 20

21 Impressions of TWIN construction

22 Thank you! 43 22