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:
“True contentment is a thing as active as agriculture. It is the power of getting out of any situation all that there is in it. It is arduous and it is rare.”
—Gilbert Keith Chesterton (1874–1936)
“We have not passed that subtle line between childhood and adulthood until we move from the passive voice to the active voice—that is, until we have stopped saying “It got lost,” and say, “I lost it.””
—Sydney J. Harris (b. 1917)