The Noto VLBI station was fully operational in 2012, and the upgrade projects could be restarted, involving mainly the receiver area. Another important improvement was the activation of the 1 Gbps network

Buttaccioi, S.

Cassaro, P.

Contavalle, C.

Nicotra, G.

Nicotra, L.

Nocita, C.

Papaleo, L.

Paterno, M.

Platania, P. R.

Schilliro, F.

Tuccari, G.

NASA Technical Reports Server

Noto VLBI Station Istituto di Radioastronomia INAF, Stazione VLBI di Noto
Noto Station Status Report
G. Tuccari, S. Buttaccio, P. Cassaro, C. Contavalle, G. Nicotra, L. Nicotra, C. Nocita,
L. Papaleo, M. Paterno´, P.R. Platania, F. Schilliro´
Abstract
The Noto VLBI station was fully operational in 2012, and the upgrade projects could be restarted,
involving mainly the receiver area. Another important improvement was the activation of the 1 Gbps
network.
1. Frequency Agility
A frequency agility system is in the design phase. The system will install a set of receivers
in the antenna secondary focus so that the receivers will automatically become operative within
a few minutes. The primary focus will receive a revised version of the SXLP receiver that was
developed some years ago but was never used due to the difficult mechanical operations required to
implement it. This frequency agility project has been funded, and the activities started in summer
2012. The C, K, Q, and W receivers will be placed in the secondary focus in fixed position to make
it possible to switch between them in a very short time. The W band will be covered by a revised
version of a receiver acquired from IRAM. This solution is particularly convenient because it can
be implemented as part of the vertex room reconstruction. The receiver will require specialized
installation because it is filled with liquid helium in order to cool it down to the 4K stage, and
the helium must remain in its tank while the antenna moves through a 0 to 90 degree range of
elevation. Noto could join the millimeter VLBI network as soon as it becomes operational.
2. Fiber Optics Connection
A fiber optics link for e-VLBI activities has been activated by the GARR (Italian Academic
and Research Network), and it is now operating at a 1 Gbps data rate since March 2012. An
upgrade increasing the connection rate up to 10 Gbps is planned to become available in the next
few months. The new connection permitted Noto to participate in the e-VLBI EVN observations
and greatly reduced the need to send disk packs to the correlators for the IVS sessions.
3. VLBI2010 at the Station
The Noto station will participate in VLBI sessions with the legacy antenna until it is possible to
install a VLBI2010 12-m antenna. Operations in this technology require adoption of a broadband
receiver and a dedicated backend. The first is under construction with a prototype feed. This
receiver covers the range 2-14 GHz and, apart from the first amplification stages, is fully digital.
Indeed no analog down-conversion is included for the entire band covered up to 14 GHz. In order to
adapt the feed to the 32-m antenna optics, an additional tertiary mirror is planned, to be installed
on the antenna surface during the observation periods. The final destination for this receiver is a
12-m fast slewing VLBI2010 compliant antenna.
The DBBC2 backend in Noto was partly upgraded to DBBC2010. This requires the installation
of a total number of eight 1 GHz bandwidth IFs to provide a total number of boards able to support
120 IVS 2012 Annual Report
https://ntrs.nasa.gov/search.jsp?R=20150003865 2019-08-31T11:10:15+00:00Z
Istituto di Radioastronomia INAF, Stazione VLBI di Noto Noto VLBI Station
eight wideband PFB (Polyphase Filter Bank) elements, for a minimum total aggregate output
data rate of 32 Gbps. A FILA10G Ethernet interface, which is already operational at several EVN
stations, is required to produce 32 Gbps output; producing more than 32 Gbps output requires
additional interfaces. Such a board will be installed in Noto in 2013, with the completion of the
DBBC2010 upgrade.
The DBBC3 project financed by Radionet started in July 2012. This project will produce the
newest front-backend system compliant with EVN32Gbps and VLBI2010. The new system will
provide the entire dual polarization VLBI2010 14 GHz broadband coverage in full digital fashion,
including the support for data processing and multiple 40G network capability. It will also include
burst modes and a buffer/recording system, which is an alternative to other VLBI high data rate
recorders and which is able to support external disk-packs at 32-64-128 Gbps. A DBBC3 schematic
block view is shown in Figure 1.
Figure 1. DBBC3 schematic block view.
4. Observations
Noto was scheduled for one 24-hour session per month, starting from February 2012, when the
antenna was again operational after the azimuth track replacement. The scheduled experiments
have been: EUROPE-116, CRF67, EUR117, EUR118, T2084, EUR119, T2085, CRF70, T2086,
IVS 2012 Annual Report 121
Noto VLBI Station Istituto di Radioastronomia INAF, Stazione VLBI di Noto
EUR120, and CRF71. Due to the high number of inoperative, old analog baseband converters, the
efficiency was not as desired. A great effort was made to reactivate the maximum possible number
of such units, but the actual solution to the problem will come with the operational introduction
of the upgraded DBBC backend, in the first half of 2013.
122 IVS 2012 Annual Report


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