The US DCL (Detection Classification and Localisation) demonstrator program is aimed at proving that an active torpedo detection system is able to resolve a salvo of torpedoes with sufficient time and accuracy that an anti-torpedo torpedo may be fired back to hit and destroy the threat. The DCL systems consist of an active source emitter which sends high-frequency pings into the water. Reflections from in-water objects are received by a towed array tuned to those frequencies. By processing the reflections it is possible to determine whether objects are torpedoes, or non-threat objects.