Date: Mon, 15 Aug 1994 12:19:01 -0600 (MDT) From: "Rob Slade, Ed. DECrypt & ComNet, VARUG rep, 604-984-4067" Subject: "Understanding Data Communications" by Held BKUNDTCM.RVW 940603 SAMS 11711 N. College Ave., Suite 140 Carmel, IN 46032-5634 317-573-2500 317-581-3535 800-428-5331 800-428-3804 or 201 West 103rd St. Indianapolis, IN 46290 317-581-3718 fax: 317-581-4669 "Understanding Data Communications", Held, 1991, 0-672-30005-2, U$24.95/C$31.95 The first edition of this book had six authors, and one could therefore have understood some disjointedness between chapters. The second and third editions, however, were revised by a single author. Why, then, does this purported textbook seem more like a collection of essays only loosely linked by a common topic? The choice of topics for the chapters seems to be quite "application" specific for a general text on data communications. The overview of chapter one is the usual historical look at various electronic communications systems. Chapter two, "Data Terminals", is quite dated, as well as displaying a decided IBM bias in both terminology and concepts. Chapter three is supposed to say something about messages, but concentrates primarily on transmission media. This chapter highlights the widely varying technical level in the book, as well as the disorganization of the material. There are discussions of attenuation and impedance, as well as lists of utilized frequencies--but no discussion of keying or fibre optic functioning. Although the definitions of keying and fibre optics are missing, certain details are discussed--which make little sense without the background. Chapters four and five discuss modems. Again, the discussion is quite anachronistic, and, again, the content fails to find a logical flow. Keying is discussed in chapter four--but only frequency shift keying. Chapter five then details quadrature amplitude modulation--which makes little sense without amplitude and phase shift keying. (Actually, amplitude and phase shift keying were illustrated in chapter four--literally. The figures in the book are generally clear when they list tables of information, but the graphical figures are often incomprehensible.) Chapters six to twelve are again mostly concerned with specific applications; multiplexing, fibre and satellite, protocols, LANs, packet data, network management and ISDN. The questions at the end of each chapter are not only highly simplistic but also "multiple guess". It would be difficult to use this as a comprehensive text for data communications. In spite of the flaws, however, there is some good information buried here. The engineering and hardware aspects of data communications is quite strong, and this tends to be a weakness in some other texts. Therefore, while not perhaps suitable as the sole text for a data comm course, it may see good use as an adjunct text or reference. copyright Robert M. Slade, 1994 BKUNDTCM.RVW 940603 ====================== DECUS Canada Communications, Desktop, Education and Security group newsletters Editor and/or reviewer ROBERTS@decus.ca, RSlade@sfu.ca, Rob Slade at 1:153/733 DECUS Symposium '95, Toronto, ON, February 13-17, 1995, contact: rulag@decus.ca