The Vital but Little-Known Radio Direction Finders
US forces in Vietnam had such a decisive firepower and training advantage over their communist adversaries, that pitched battles inevitably ended in lopsided American victories. After a few hard lessons, the communists eventually learned that, and learned to avoid stand up fights with the US military. They hid in jungles, mountains, deltas, and other inaccessible terrain, and fought a guerrilla war of ambushes and hit and run attacks. Before American firepower could be brought down to annihilate them, they broke off contact, and faded back into their lairs and hideouts. Finding the enemy thus became the most important – and most frustrating – task faced by the US military in Vietnam.
The lion’s share of the ASA’s workload in Vietnam revolved around the interception of communist forces’ radio signals. If deciphered, the signal’s contents were passed on for further action, but even if a signal could not be deciphered, its very existence was still useful. ASA personnel used Ground Radio Direction Finding (GRDF) and Airborne Radio Direction Finding (ARDF) devices to identify and triangulate the location of communist forces’ radio transmitters. Such radio transmitters were often located close to enemy headquarters and hostile troop concentrations, so pinning down their location helped locate the often hard to find communist forces. Because of just how important – and difficult – finding the enemy in Vietnam was, ARDF units were described as: “the single most valuable intelligence resource available to American and allied forces during the war in Vietnam“.