Active / Passive Locators
Active locators have some sort of signal generation device, in addition to a listening device. The two devices do not have to be located together.
Read more about this topic: Acoustic Location
Famous quotes containing the words active and/or passive:
“Even if you find yourself in a heated exchange with your toddler, it is better for your child to feel the heat rather than for him to feel you withdraw emotionally.... Active and emotional involvement between parent and child helps the child make the limits a part of himself.”
—Stanley I. Greenspan (20th century)
“To make oneself an object, to make oneself passive, is a very different thing from being a passive object.”
—Simone De Beauvoir (1908–1986)