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Enhancing the European VLBI Network of Radio Telescopes


Original research objectives:
a. for the EVN Data Processor at Joint Institute for VLBI in Europe (JIVE), development of a post-correlation integrator subsystem involving high-speed readout electronics to allow the full design capabilities of the data processor for multiple field centre correlation, pulsar gating and high spectral resolution to be exploited.
b. development of radio astronomical receivers (detectors) which can operate in an increasingly hostile radio frequency interference (RFI) environment.
c. development of new experimental techniques to take advantage of new and unique hardware capabilities of the data processor at JIVE.
d. a study of optical fibre data transfer between the radio telescopes and data processor, with the eventual goal of replacing tape recorders.

Expected deliverables:
1. A prototype post-correlator integrator for the EVN MkIV data processor.
2. A prototype receiver in the frequency range 250 - 1200 MHz which is less sensitive to RFI than current devices.
3. Demonstration of Cluster-Cluster, multiple field centre, pulsar gating and high spectral resolution techniques can be used in conjunction with the new correlator.
4. A feasibility study of the use of optical fibres in a VLBI network.
1). The EVN MkIV correlator at JIVE has been upgraded with the performance-enhancing DSP software. The design study of the novel hardware item, the Post Correlator Integrator (PCI) was completed. The design has been confirmed as suitable for replication for a full production system. Successful tests of the new hard- and software elements of the PCI have been conducted.

2). All observatories participating in the project continued monitoring of the RFI situation. RFI monitoring data are being produced routinely since the end of 1999. The RFI monitoring will continue after completion of the present contract.

3). The design concept of the Feed Forward System (FFS) for the RFI-robust receiver was accepted as a basis for the detailed design of the receiver. The design study resulted in the production of a laboratory prototype of the FFS system and its successful tests at the ASTRON Technical Laboratory (NFRA) in Dwingeloo

4). A special test observation using the EVN telescopes was completed to demonstrate the wide-field capability of the new MkIV correlator. The result of correlation and post-processing indicated that the test had been successful (more details in the report on this subject).

A Cluster-Cluster VLBI experiment was conducted, and the data analysed (see details in the final report on the Cluster-Cluster VLBI technique).

The first Pulsar-gating experiment was successfully correlated at the MkIV correlator at JIVE.

The VLBI Field System has been developed by joint efforts of the university of Helsinki and the NVI, Inc. (USA) sub-contacted by JIVE.

5). The preliminary design of optical fibre links for EVN and respective cost estimates were prepared. Further work aimed at a "live'" demonstration of real-time fibre links between several EVN telescopes and the MkIV correlator at JIVE commenced. The work is based on the results published in the final report on the sub-project 4 "Optical Fibre Communications between Radio Telescopes in the European VLBI Network" (released in June 2000).

Funding Scheme

LFC - Access to Research Infrastructures


4,Oude Hoogeveensdijk 4
7990 AA Dwingeloo

Participants (5)

Conseil National de Recherche

Netherlands Foundation for Research in Astronomy
Victoria University of Manchester
United Kingdom