Abstracts Astronomy & Space Science

Digital data processing in radio astronomy

by Mark David Apperley

Research in radio astronomy at the University of Aucklan School of Engineering has been in progress for a period of six years. The program was initiated primarily to provide a variety of topics for post-graduate research in the Department of Electrical Engineering, and at the same time to develop a useful radio telescope installation. Initial work was concentrated on the development of antenna arrays (Lim, 1968) and low noise receivers at a frequency of 42MHz, utilising both phase-switched and correlation interferometer principles (Irving, 1966; Yarrall, 1968; Saunders, 1968). At the beginning of 1969, the Department moved from its former country site into the centre of Auckland city. As no alternative field site was available, the telescope was also moved, but space limitations meant that the city site was inadequate for any useful observations at 42MHz. It became clear that to utilise the site more fully a higher observation frequency would be necessary, and a frequency of 200MHz was chosen, as this was the upper limit of most of the available laboratory equipment, yet still within the range of semiconductor devices. In view of the inadequacies of the site, it was obvious that the performance of the system could be significantly improved by processing the output in a digital computer.