Infrared wireless transmission can be either directed or diffused. A directed transmission
requires that the emitter and detector be directly aimed at one another (called the lineof-
sight principle), as shown in Figure 2-4. The emitter sends a narrowly focused beam of
infrared light. The detector has a small receiving or viewing area. A television remote control,
for example, uses directed transmission, and this is the reason that most of us point the
remote at the TV or other remote-controlled devices.