Chapter 10. Digital vs. Analog: Communications Basics

Years of taking "walking around polls" reveals a startling fact—excluding engineers and scientists, the percentage of the population that actually understand the difference between digital and analog communications hovers around zero. Since it is extremely difficult to comprehend developments in computers and communications without being conversant with digital systems, this chapter will focus on three fundamental aspects of the digital communications revolution. The first section covers the ways in which information can be carried in communications. It explains the difference between analog and digital and gives meaning to the popular term bandwidth. The second and third sections describe how engineers have dealt with the two principal challenges of digital communications: 1) the need to compress data so that it can fit into communications channels, and 2) making sure that what is sent and what is received are the same by providing error detection and correction systems. By the end of this chapter you should understand

• How frequency waves can carry information and what bandwidth really means

• The difference between analog and digital means of sending data

• The reasons that digital communications are superior for most purposes

• How digital information can be compressed to conserve bandwidth

• Why is it possible to send digital data with a high degree of accuracy