 The indicator loop was supplemented with a photo-electric beam above the water, to detect the presence of surface vessels entering the Brisbane River.RAN Station 9 in Brisbane was one of only three photo-electric beam installations built in Australia during World War II, the others being between South Head and Middle Head in Sydney, and between Point Lonsdale and Point Nepean at Port Phillip in Melbourne.Lieutenant Colonel Buckland of the Australian Army was responsible for the installation of all three.