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29th of March 2022
ATCA data flows
The Australia Telescope Compact Array (ATCA) at Narrabri is built on the site of the Culgoora Radio-heliograph, which operated from 1967 to 1984. Five of the ATCA's six 22-m antennas are visible in the image above. Data from these antennas are taken by optical fibre to the correlator in the central Control Building for processing. The image above also shows the remains of the data transmission system of the old Radioheliograph, which consisted of 96 13-m diameter dishes spaced around a circle of 3km diameter. The signals from each antenna had to be transmitted to the Control Building at the observing frequency of 80 MHz. Coaxial cable would normally be used, but affordable coaxial cable suffered from too much attenuation over the 1.5 km distance. Instead, a system of open-wire copper transmission lines were used. While a much more economical solution, care had to be taken in keeping cross-coupling between lines to a low level, and minimizing electrical connections at support points. The posts just to the left of centre of the image above were two of many used to bring the signals from the 96 antennas to the Control Building.

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