e design, philosophy, structure, and use of data com- munications protocols. Chapter 1 Questions What is the difference between telecommunications and data communications? What is the difference between a protocol and a standard? Why do you suppose the United Nations has global responsibility for the development of telecommunications standards? Why are there so many different standards bodies? How do they work together to ensure global acceptance of new standards? Give examples of each of the following: simplex, half-duplex, and full-duplex services. Which are most common? What is the difference between intelligibility and recognizability? Define the following terms: amplitude modulation, frequency modulation, and phase modulation. Explain the difference between data encoding and signaling. It is possible to transport digital data across an analog facility. Explain. In simple terms, explain the difference between the work done by Harry Nyquist and Claude Shannon. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. First Things First Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. CHAPTER Protocols Protocols Chapter 2 Click. One simple action that kicks off a complex series of events that results in the transmission of an e-mail message, or in the creation of a digital medical image, or in the establishment of a videoconference between a child and a grandmother. The process through which this hap- pens is a remarkable symphony of technological complexity, and it is all governed by a collection of rules called protocols. This chapter is dedi- cated to them. Data Communications Systems and Functions If I were to walk up to you on the street in pretty much any Western country, 