In this chapter we review the basic concepts of digital modulation and demodulation in the absence of noise. Digital modulation is the process of mapping information bits into transmitted waveforms. Demodulation is the process of mapping received signals back into bits. Concepts from signals and systems that are needed in understanding modulation and demodulation are reviewed.
Because sinusoidal signals are fundamental in communication systems, we first review representations of sinusoidal signals. Next, we show how vectors can be mapped into waveforms, as described in Chapter 1. For binary modulation, 1 bit of information (a 0 or a 1) is mapped into one of two vectors. These vectors along with a set of orthonormal waveforms (described below) determine two signals. So 1 bit of information will be mapped into one of two signals that is transmitted.
Review the options below to login to check your access.
Log in with your Cambridge Higher Education account to check access.
If you believe you should have access to this content, please contact your institutional librarian or consult our FAQ page for further information about accessing our content.