tomatic Switching Systems 4.3.6 Common Control (Hard-Wired) 4.3.7 Stored Program Control 4.3.8 Concentrators and Remote Switching CONTENTS Essential Concepts in Transmission 4.4.1 Introduction 4.4.2 Two-Wire and Four-Wire Transmission 4.5 Introduction to Multiplexing 4.5.1 Definition 4.5.2 Frequency Division Multiplex 4.5.3 Pilot Tones 4.5.4 Comments on the Employment and Disadvantages of FDM Systems Review Exercises References Chapter 5 Transmission Aspects of Voice Telephony Chapter Objective Definition of the Voice Channel 5.2.1 The Human Voice Operation of the Telephone Subset 5.3.1 The Subset Mouthpiece or Transmitter 5.3.2 The Subset Earpiece or Receiver Subscriber Loop Design 5.4.1 Basic Design Considerations 5.4.2 Subscriber Loop Length Limits 5.4.3 Designing a Subscriber Loop 5.4.4 Extending the Subscriber Loop 5.4.5 "Cookbook" Design Methods for Subscriber Loops 5.4.6 Present North American Loop Design Rules Design of Local Area Wire-Pair Trunks (Junctions) 5.5.1 Introduction 5.5.2 Inductive Loading of Wire-Pair Trunks (Junctions) 5.5.3 Local Trunk (Junction) Design Considerations VF Repeaters (Amplifiers) Review Exercises References Chapter 6 Digital Networks Introduction to Digital Transmission 6.1.1 Two Different PCM Standards 6.2 Basis of Pulse Code Modulation 6.2.1 Sampling 6.2.2 Quantization 6.2.3 Coding PCM System Operation 6.4 Line Code Signal-to-Gaussian-Noise Ratio on PCM Repeatered Lines CONTENTS Regenerative Repeaters PCM System Enhancements 6.7.1 Enhancements to DS1 6.7.2 Enhancements to E1 6.8 Higher-Order PCM Multiplex Systems 6.8.1 Introduction 6.8.2 Stuffing and Justification 6.8.3 North American Higher-Level Multiplex 6.8.4 European E1 Digital Hierarchy 6.9 Long-Distance PCM Transmission 6.9.1 Transmission Limitations 6.9.2 Jitter and Wander 6.9.3 Distortion 6.9.4 Thermal Noise 6.9.5 Crosstalk Digital Loop Carrier 6.10.1 New Versions of DSL Digital Switching 6.11.1 Advantages and Issues of Digital Switching 6.11.2 Approaches to PCM Switching 6.11.3 Review of Some Digital Switching Conc