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Дата индексирования: Sun Feb 3 17:48:31 2013
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The main principles of the new generation Russian VLBI network development
·Radio telescopes of this network should be fully compatible with QUSAR radio telescopes. ·This project should be based on the results of VLBI-2010 work group. ·The real site radio climate conditions should be taken into account. ·Radio telescopes should work on 24 by 7 basis. ·Radio telescopes should be placed at maximal longitude distance from each other.

Proposed location of the new generation Russian VLBI network radio telescopes

Kaliningrad

St. Petersburg

Zelenchukskaya (Zc) Badary (Bd) Ussurijsk

Working frequency bands for the new generation Russian VLBI network
S X Ka

2.2 2.6

7.0

9.5

27

33 F, GHz

Data acquisition parameters 4 frequency bands: 512 MHz bandwidth x 2 polarisations or 1024 MHz bandwidth x 1 polarisation 2-bit sampling Data rate 2 Gbps in each channel 16 Gbps total

First project stage Frequency bands placing
3 bands side by side, on 8.0 9.5 GHz frequencies (X-band), for group delay obtaining 1 band on 2.2 GHz (S-band), near to 300 MHz bandwidth really (high noise) for ionosphere delay calculation

S

X

Ka

2 .2 2 .6

7 .0

9 .5

27

33

F, GHz

Group delay accuracy to 4 ps

Second project stage Frequency bands placing
3 bands, on 27 33 GHz frequencies (Ka-band), with 6 GGz synthesis bandwidth for group delay obtaining 1 band on 8-9 GHz (X-band) for ionosphere delay calculation
S X Ka

2.2 2.6

7.0

9.5

27

33 F, GHz

Group delay accuracy to 2 ps

Future system
"Bill Petrachenko" projects Preliminary frequency channels placing, 4 bands:
ba ba ba ba nd nd nd nd o o o o n n n n 2.2 GHz 6.4 GHz 8.2 GHz 13.5 GHz

Synthesis bandwidth from 2 to 14 GHz
S X Ka

2

6

8

14

F, GHz

Group delay accuracy up to 1 ps (theoretical)

New 13.2 m VERTEX antenna in Wettzell

Antenna reflection system geometry

The three-band S, X and Ka feed for the new generation Russian VLBI network

Front-end block scheme for the new generation Russian VLBI network

S

The Digital Data Acquisition System for the new generation Russian VLBI network

The prototype of the DSP unit of the Digital Data Acquisition System

The prototype of the DSP unit of the Digital Data Acquisition System

First test experiment of the prototype of the DSP unit of the Digital Data Acquisition System

Svetloe - Zelenchukskaya Source 1803+784, Flux ~2 Jy, X band, RCP, f = 512 MHz, ti = 2 sec SNR ~135 (theoretical 186)

Phase compensation system
5MHz

Active Hydrogen Frequency Standard

5MHz 100MHz

в
5MHz

VCXO 95MHz

в

5MHz Driver of the optical transceiver 100MHz

ref

в
100MHz

95MHz

Conversion scheme RFsignal into an optical signal

в
VCXO 105MHz

VCXO 5MHz

в
5MHz

в

100MHz

5 MHz

= ref -d

el a y

Optical transceiver optical isolator
1

105MHz

в
100MHz

5MHz
5

3

Cable delay compensation scheme

Amplifier

Optical receiver

2

laboratory building Optical fibre link
2 5 3 1

Conversion scheme of the optical signal in the RF-signal

5MHz

delay

Optical receiver Amplifier
Driver of the optical transceiver

ref

Conversion scheme of the optical signal in the RF-signal

Conversion scheme RFsignal into an optical signal

RF Distribution Amplifier

5MHz

M ul t i pl i e d output

100MHz

Optical transceiver optical isolator

telescope

Parts of phase compensation system

Conversion scheme RFs i g n a l i n to a n o p ti c a l s i g n a l

Conversion scheme of the optical signal in the RF-signal

Optical Circulator and o p ti c a l i s o l a to r

Frequency instability (Allan variance) after passing through the optical cable (the results of the experiment)
Integration time, s 1 10 100 1000 Frequency instability at the input of the optical transceiver 4,7·10 5,7·10 1,3·10 3,6·10
-13 -14 -14 -15

The instability of the signal after conversion RF signaloptical signalRF-signal 5,4·10 8,3·10 1,7·10 5,1·10
-13 -14 -14 -15

Software Correlator for data processing for new generation VLBI network

Input data:
6 1 4 2 2 5 2 stations 6 Gbps from each station frequency bands, polarizations, Gbps in each channel 12 MHz bandwidth, -bit sampling
FX program correlator Realising on blade-servers with NVIDIA's GPU Blade-servers T-Platforms V-Class V200F 2CPU Intel E5-2670, 8-core, 2.6 GHz, 2NVidia Tesla M2090 on each blade-server

Correlating
Each polarization of one station with each polarization of another station for each frequency band 4096 points of cross-spectra Multiple tones of calibration signals from each band

Water vapour radiometer

Parameters : Frequency bands: 21 GHz 32 GHz T ~ 50-60mK , = 1s (Ts 120K-190K, f 0,5GHz), G/G ~ (2В3)·10-4 on 10 В 60 minutes Total power measurement Continuous observations Two-level thermo stabilization WVR prototype in Svetloe Observatory

Badary Observatory
-2010 , 11-12

20