TABLE OF CONTENTS This chapter describes the wide variety of transmission systems used in telecommunications networks today. In doing this, we will be drawing upon the concepts of multiplexing and analogue to digital conversion introduced in the previous chapter. Earlier chapters have also introduced the important distinction between the access network, which serves the subscribers, and the core transmission network, which provides links between network nodes only. In general, the transmission systems described in this chapter may be deployed in both the access and the core transmission networks although they are usually more appropriate to one or the other, and this will be indicated. Chapter 2 introduced the model of the networks associated with the PSTN (Fig. 2.11), in which the access and core transmission networks act as a common utility for providing circuits to the various specialised networks as well as the PSTN. However, we will leave the description of how the various transmission systems are deployed in the access and core transmission networks until Chapter 5.
