TABLE OF CONTENTS Alan Bensky
In this chapter we take an overall view of the characteristics of the communication system. While these characteristics are common to any wireless communication link, for detail we ll address the peculiarities of short-range systems.
A simple block diagram of a digital wireless link is shown in Figure 6.1. The link transfers information originating at one location, referred to as source data, to another location where it is referred to as reconstructed data. A more concrete implementation of a wireless system, a security system, is shown in Figure 6.2.
Let s first take a look at what information we may want to transfer to the other side. This is important in determining what bandwidth the system needs.
Many short-range systems only have to relay information about the state of a contact. This is true of the security system of Figure 6.2 where an infrared motion detector notifies the control panel when motion is detected. Another example is the push-button transmitter, which may be used as a panic button or as a way to activate and deactivate the control system, or a wireless smoke detector, which gives advance warning of an impending fire. There are also what are often referred to as technical alarms gas detectors, water level detectors, and low and high temperature detectors whose function is to give notice of an abnormal situation.
All these...
