BKULMDHB.RVW   980115

"The Ultimate Modem Handbook", Cass R. Lewart, 1998, 0-13-849415-0,
U$39.95/C$56.00
%A   Cass R. Lewart
%C   One Lake St., Upper Saddle River, NJ   07458
%D   1998
%G   0-13-849415-0
%I   Prentice Hall
%O   U$39.95/C$56.00 800-576-3800 betsy_carey@prenhall.com
%P   426 p. + CD-ROM
%T   "The Ultimate Modem Handbook"

A handbook tends to indicate either small size, or a compendium of
reference information.  This book is neither small nor a particularly
good reference, but it is quite complete.

The introduction to data communications given in chapter one is quite
technical, and generic.  Chapter two, although ostensibly about modem
speeds, is probably of interest only to engineering students.  I'm not
sure why it was divided from chapter three, on modulation techniques. 
The material starts to become slightly less technical, and possibly of
more use to the modem installing reader at this point.  Certainly
chapter four, dealing with data communications, and particularly
modem, protocol standards is a very useful reference in choosing a
modem.  Chapter five discusses synchronous and asynchronous
transmission, again, mostly of interest to the professional.  The
serial interface, in chapter six, blends the technical and more
general material reasonably well.

Part two is a more practical section, and the home user might be well
advised to skip part one for the moment and start here.  Chapter seven
does not repeat the discussion of protocols, but otherwise is a fairly
complete and useful guide to modem choice and purchase.  The
installation instructions, in chapter eight, are a bit more complete
and informative than the usual optimistic guide.  However, I doubt
that it would be an awful lot of help in the all too frequent case
that installation did *not* go as advertised.  Lewart, like most modem
book authors, is rather willing to believe that there are "standard"
AT command sets, but he does at least provide a handy means of
communicating directly with the modem under Windows 95 in the command
set discussion in chapter nine.  Chapter ten, on communications
software, also suffers from limited exposure.  However, I can forgive
a lot to someone who finally knows how good Kermit is.  He also
touches briefly on compression, encoding, and encryption.  Oddly,
though, the whole class of Internet software is left until chapter
eleven, which talks about who you can call.  Chapter twelve gets back
into the real techie stuff, with circuit diagrams for the Rockwell
chipset modems.  This chapter also contains additional AT commands for
fax modems.

Part three looks at specialized modems, with chapter thirteen covering
the commercial modem standards other than those common in home use. 
Chapter fourteen deals with ISDN (Integrated Services Digital
Network), cable, wireless, and combination modems.  Chapter fifteen
covers limited distance modems.

Part four offers troubleshooting tips and guidance.  Chapter sixteen
suggests testing, most of which the home user can do, but some of
which will be available only to the professional.  Some fixes are
easier than others: under "Frequent disconnects" one of the possible
causes is poor line quality and the suggested remedy is to "try to
convince the phone company to improve your phone line."  I had to call
monthly for two years to get BC Tel to check egregious line noise
whenever the weather turned suddenly cold or wet.  After all that, it
was traced to an improper connection in the junction box.  End of line
noise.  However, Lewart also suggests turning *off* the error
correction software.  I don't understand that suggestion, since error
correction can deal quite well with low level and sporadic line noise. 
(There was the time that I made my contribution to discussion of
fairly consistent line noise affecting one particular BBS by saying
that *I* hadn't seen any, to be told by the sysop that of course I
hadn't: I always called with an error correcting modem.)  Chapter
seventeen is back to engineering class, with attenuation and frequency
graphs.  Chapter eighteen projects into the future for possible
emerging technologies.

In the preface, Lewart states that this book is for both the personal
computer user, and for the communications professional.  Even given
these two distinct audiences, the material is both too technical, and
not technical enough.  The first chapter, introducing data
communications concepts, is a case in point.  The text describes the
two-wire and four-wire options for the local loop.  
However, it does not enlighten the reader as to why one should need to
know about the number of wires in the local phone circuit or hybrid
circuits, and neither the written content nor the illustrations
explain why a four-wire loop can be used to send high-speed data over
longer distances.  Again, there is a five page overview of the OSI
(Open Systems Interconnection) model of networking in a book which is
going to deal with only the physical (or, at most, the data link)
layer.  Information on Nyquist, Shannon, and noise due to digital
quantization is of use only to modem engineers, and the material given
here is too limited to be of use to them.  (The figures and tables are
particularly useless in the book.  Even knowing the field I was often
unable to determine what was supposed to be illustrated or clarified
by a figure.  Generally they add no explanatory value to what is being
discussed.)

While sometimes too technical, and occasionally pedantic, this book is
nonetheless much more accurate, and generally more complete, than the
bulk of the modem library.  Some gaps could be filled, and care could
be taken with the writing level, but for those needing a modem guide,
this should be considered.

copyright Robert M. Slade, 1998   BKULMDHB.RVW   980115