ISDN Explained [antikvár]

Preface Five years ago, when the first edition of this book was written, ISDN was a matter of specialist interest; now it is becoming commonplace and for that reason is routinely part of telecommunications courses at all levels. It is therefore right that this book should be issued in a form suitable for student use. This book is pitched at a level deeper than the general "gee-whiz, isn't it wonderful" by going into the principles of all facets of the ISDN operation. It does not pretend to go down to the detail needed to build network or terminal equipment. The full details would require a book several times the size of this but it does set out the principles on which the whole lot works. This book gives an overview to set the operations in context, to introduce Standards, Recommendations and operating manuals. Changes to this book from the second edition have involved the rewriting of some areas in which I felt there was scope for making explanations easier to understand; in this connection I would like to thank Iain Richardson of The Robert Gordon University for the graphical way of explaining the DCT in chapter 8. I have also included a "route map" to ISDN, printed on the inside cover, which sets out to clarify the ISDN story by indicating the relationship between the various strands. Readers may also wish to note that references to "CCITT" are now more properly to "ITU-T" as a result of changes in that organisation. The work recorded in this book is the result of many people's inspiration. I would like to thank the contributors to this book who have filled in their own areas of expertise. However, in addition to all those mentioned by name, there were also many others whose advice and information have also contributed and whom I must thank. I would also like to compliment Peter Adams, who wrote chapter 4, for his leadership of the team at BT Labs whose work on local network transmission and the 2B1Q line code has led to what has become the standard local network ix