ABSTRACT
The essence of an acoustic remote-sensing system is in generating sound into a wellformed beam which interacts with the atmosphere in a known manner and then detecting that interaction. In Chapter 2 we learned about the nature of the atmosphere into which the sound is projected, and in Chapter 3 the way in which sound travels. In this chapter we describe how to form a beam of sound, how scattered sound is detected, and how systems are designed to optimize retrieval of various atmospheric parameters. The main emphasis of Chapter 4 is on geometry and timing, but details on some of these aspects are left to Chapter 5.
