Digital Communications Fundamentals
Michel Terré, Mylène Pischella, Emmanuelle Vivier · 2013
This chapter focuses on digital communications fundamentals. The most useful signal processing tool to perform signal-to-noise ratio calculations is the mathematically expected value. Digital modulations allow us to transmit several bits at the same time in a given symbol time. For this purpose, bits are grouped into symbols. Two types of modulations can be distinguished: linear modulations and frequency modulations. Three main types of linear modulations exist: amplitude modulations (amplitude shift keying (ASK)), phase modulations (phase shift keying (PSK)) and amplitude and phase modulations (quadrature amplitude modulation (QAM)). The chapter talks about linear equalization and nonlinear equalization. It explains ASK 2 modulation error probability and discusses spectral occupancy, symbol rate and binary throughput. The chapter compares 16-QAM and 16-PSK modulations and presents zero-forcing linear equalization and minimum mean square error (MMSE) equalization. Controlled Vocabulary Terms amplitude shift keying; digital communication; least mean squares methods; phase shift keying; quadrature amplitude modulation; signal to noise ratio