In the 1930's the Allied Anti-Submarine Detection Committee invented a method of interpreting an echo generated by a burst of energy reflecting off of a naval target. The Americans named the technique "sonar" after its acronym sound navigation and ranging. Sonar could identify the range, speed, distance, and direction of both surface vessels and submarines. Sonar buoys remained hidden from the enemy though they allowed military intelligence to remotely gather information about the enemy's naval activities.