Teach Yourself Electricity and Electronics, Sixth Edition, 6th Edition

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CHAPTER

Wireless Transmitters and Receivers

IN WIRELESS COMMUNICATIONS, A TRANSMITTER CONVERTS DATA INTO ELECTROMAGNETIC (EM) WAVES intended for recovery by one or more receivers. In this chapter, we’ll learn how to convert data to an EM field, and then learn how we can intercept and decode that field at remote points.

Modulation

When we modulate a wireless signal, we “write” data onto an EM wave. We can carry out this process by varying the amplitude, the frequency, or the phase of the wave. We can also obtain a modulated signal by generating a series of multiple-wave pulses and varying their duration, amplitude, or timing. The heart of a wireless signal comprises a sine wave called the carrier whose frequency can range from a few kilohertz ...