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:
“Many writers who choose to be active in the world lose not virtue but time, and that stillness without which literature cannot be made.”
—Gore Vidal (b. 1925)
“It is my conviction that in general women are more snobbish and class conscious than men and that these ignoble traits are a product of men’s attitude toward women and women’s passive acceptance of this attitude.”
—Mary Barnett Gilson (1877–?)