The 547 Signal Troop was deployed to Vietnam in March 1966 and returned in December 1971. Its main task was to identify and locate enemy units by intercepting radio communications. The enemy would send messages in quick bursts of Morse code.

The signalers worked at the Australian task-force base at Nui Dat, and in the air in light planes packed with sensitive monitoring equipment. Over the period of the Vietnam War 200 to 300 men went through the unit.

The troop also used light planes such as the Cessna 180A in covert missions to intercept radio signals. Two missions were flown every day at low altitude in a straight line which of course made those aircraft very attractive targets. Using equipment produced by the Weapons Research Establishment in Adelaide, they were able to locate enemy radio stations.

The North Vietnamese were aware that the Americans were intercepting them because the American technique was to fly the aircraft directly at the enemy radio station. But nobody assumed that Australians would have such proficient operators and the Australian radio direction finding technique was "fly past". That is, the aircraft did not point at the enemy radio station. There was so much aircraft activity in Vietnam that one more airplane flying passed that it didn't draw the attention of enemy radio operators.