UNDERSTAND1 -1 NC STEPHEN 1. BICELOW JOSEPH J. CARR STEVE WINDER Understanding Te I e p h o ne Electronics Fourth Edition Understanding Telephone Electronics Fourth Edition Stephen J. Bigelow Joseph J. Carr Steve Winder Newnes Boston Oxford Auckland Johannesburg Melbourne New Delhi Newnes is an imprint of Buttenvorth-Heinemann. Copyright 0 200 1 by Buttenvorth-Heinemann GA member of the Reed Elsevier group All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Recognizing the importance of preserving what has been written, Buttenvorth- Library of Congress Cataloging-in-Publication Data Bigelow, Stephen J. @ Heinemann prints its books on acid-free paper whenever possible. Understanding telephone electronics / Stephen J. Bigelow, Joseph J. Carr, Rev. ed. of: Understanding telephone electronics, 3rd ed. 1997. Includes index. ISBN 0-7506-7175-0 (pbk. : alk. paper) 1. Telephone. I. Carr, Jose h J. 11. Winder, Stephen W. 111. Understanding Stephen W. Winder. p. cm. telephone electronics. IV. Tile. TK6162 .C37 2001 621.385-4~2 1 2001030412 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. The publisher offers special discounts on bulk orders of this book. For information, please contact: Manager of Special Sales Butterworth-Heinemann 225 Wildwood Avenue Woburn, MA 01801-2041 Tel: 781-904-2500 For information on all Newnes publications available, contact our World Wide Web home page at: http://www.newnespress.com 10987654321 Printed in the United States of America Fa: 78 1-904-2620 [...]... = 1 b- TRANSMITTER I i ' I ' TELEPHONE /CRADLE T(TIP) / -I a Telephone Set Circuits TONE GENERATOR s3 TALKING BATTERY b Central Office Circuits UNDERSTANDING TELEPHONE ELECTRONICS 5 1 THE TELEPHONE SYSTEM Figure 1-3 Early Telephone with Separate Receiver Hanging on Switchhook Sending a Number Some older telephone sets send the telephone number by dial pulses while newer telephones send it by audio... the called phone to let the caller know that the exchange is ready to accept a telephone number (The telephone number also may be referred to as an address.) UNDERSTANDINGTELEPHONE ELECTRONICS 1 THE TELEPHONE SYSTEM Figure 1-2 Telephone Set and Central Office Exchange Simplified Circuits (Source: D L Cannon and G Luecke, Understanding Communications Systems, SAMs, a Division of Macmillan Computer Publishing,... to occm 10 UNDERSTANDINGTELEPHONE ELECTRONICS 1 THE TELEPHONE SYSTEM Figure 1-5 Local Network FEEDER ROUTE BOUNDARY BLOCK ’ OF HOUSES - SERVING AREA INTERFACE , SERVING AREA BOUNDARY I L_ _ _ _ _ _ _ _-I I I _ _ _ _ _ _ _ _J L a Local Distribution Area , SERVING AREA INTERFACE NUMBER OF HOUSING UNITS SERVED BY THIS CABLE b Detail of a Serving Area UNDERSTANDINGTELEPHONE ELECTRONICS 11 1 THE TELEPHONE. .. system is ready for use by receiving a tone, called the dial tone UNDERSTANDING TELEPHONE ELECTRONICS THE TELEPHONE SYSTEM 1 Figure 1-1 Telephone Set (Courtesy Radio Shack) I 3 It sends the number of the telephone to be called to the system This number is initiated by the caller when the number is pressed (or the dial is rotated in older telephones) 4 It indicates the state of a call in progress by receiving... network facilities are currently compatible with Touchtones (tone pulse dialing telephones, today’s standard embraces the Touchtone method of dialing dialing) 0 UNDERSTANDING TELEPHONE ELECTRONICS THE TELEPHONE SYSTEM 1 Dual-Tone Multifrequency Most modern telephone sets employ the newer method of using audio tones to send the telephone number called the dual-tone multifrequency (DTMF) method Audio tones... insightful developmental reviews were invaluable to us in planning this edition xiv UNDERSTANDINGTELEPHONE ELECTRONICS 1 The Telephone System ABOUTTHIS CHAPTER The telephone was invented a little over a hundred years ago by Alexander Graham Bell The telephone industry has since become one of the largest on earth The telephone arrived as a practical instrument over a century ago in 1876, an outgrowth... level in volts, Z is the impedance in ohms 14 UNDERSTANDINGTELEPHONE ELECTRONICS THE TELEPHONE SYSTEM Figure 1-8 In-Band and Out-of-Band Signaling OUTPUT VOLTAGE OR ENERGY OUT OF BAND ->u T 0.2 1 2 3 4 5 6 TONE DIALING SYSTEM CONTROL SIGNALS SIGNALS FREQUENCY (KILOHERTZ) Figure 1-9 Power Delivered to Wire Pair ,,,I P e , is Z UNDERSTANDING TELEPHONE ELECTRONICS = Power in watts to load = Signal... Of course, for a telephone to be of any use, it must be connected to another telephone In the very early days of telephony, the phones were simply wired together with no switching As the number of phones increased this became impractical, so the local exchange or central office was established to handle the switching and other functions UNDERSTANDING TELEPHONE ELECTRONICS 3 1 THE TELEPHONE SYSTEM THE... competing companies By the mid-1970s, several competitors obtained the capacity to offer long-distance telephone service UNDERSTANDINGTELEPHONE ELECTRONICS 1 THE TELEPHONE SYSTEM Advances in technology and the challenges of competition caused the government once again to rethink its position on the telephone monopoly On November 20, 1974, the Department of Justice filed a new antitrust suit against... telephone service We begin by presenting the fundamentals of the telephone network: how it began, what the components are, and how they are connected Next we review the basic nonelectronic telephone set We then consider the effect of microelectronics on the construction and operation of the telephone set; for example, the effect on functions such as speech signal processing and interface with the telephone . Data Bigelow, Stephen J. @ Heinemann prints its books on acid-free paper whenever possible. Understanding telephone electronics / Stephen J. Bigelow, Joseph J. Carr, Rev. ed. of: Understanding. Engineering Services, UK) for his numerous contributions and efforts in developing this new edition. Steve lent his expertise to several chapters, providing his most extensive revisions to Chapters. passes the ac ringing signal. (The ringer circuit presents a high impedance to speech signals so it has no effect on them .) When the handset is removed from its cradle, the spring-loaded