 The magazine of the Melbourne PC User Group Fax Power Major Keary |
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The ubiquitous fax machine has much more potential than most users realise, and a remarkably long history - almost as long as modern telegraphy. The word, fax, is well-entrenched in the English language (the first recorded use was in a 1948 issue of Time, which reported, "The big news about "fax" was that, technically, the bugs were pretty well worked out of it".
Telegraphy derives from the Greek for "writing". The term was coined as telegraphe by a Frenchman, Claude Chappe, who invented a semaphore device in 1791. Even the present-day concept of telegraphy - the transmission of signals as electrical impulses over wire - has a long history. Schemes were devised as early as 1727, but modern telegraphy was not firmly established until the 1830s.
In 1843, just six years after Samuel Morse filed his patent, the first fax machine was patented. Andrew Bain, a Scottish physicist, called his invention a recording telegraph; it involved styluses attached to pendulums driven by clockwork mechanisms at either end and kept in synchronisation by electromagnets and synch pulses.
In 1850 another device, called a copying telegraph, was invented by F.C.Bakewell of London. His machine used tinfoil, wrapped around a cylinder, and written on by a pen dipped in varnish; a contact was moved across the rotating cylinder by an endless screw. At the receiving end paper saturated in a chemical solution was used to record the image. It was not until 1934 that a dry paper process became available and made the technology more widely available.
As a matter of interest, Morse originally designed his code to be transmitted by means of metal type (each letter represented by its dots-and-dashes code) held in a long composing stick and passed under electrical contacts. The now-familiar key was a much later development preceded by the use of paper tape.
Pen technology also has a long history. In 1895 a device called the TelAutograph was invented; it enabled a hand-held stylus to be used to create almost identical writing at the receiving end.
Fax technology was given impetus by World War II and the post-war years saw those advances quickly taken up by business. In 1966 the first fax standard, RS-328, was issued.
Further development was inhibited by AT&T's monopoly of the American telephone network. They claimed to be concerned about possible damage caused by non-compliant signals and would permit only their own equipment to be connected, an impediment not fully removed until the late 70s.
Digital facsimile and integrated circuits made their appearance shortly afterwards and, with the parallel development of high speed data transmission and compression techniques, resulted in the fax as we know it.
The Fax-Modem
The capacity to create a raster (digitised image) file directly from a computer-generated document has made the fax-modem a powerful communications tool. However, not all fax-modems are equal: there are dumb ones, smart ones, CAS-compatible, Faxbios, and T.611-compliant equipment.
Most current fax-modem equipment provides the same speed for both data transmission and fax. If you are thinking of buying one, an important consideration is the intended primary use. If mostly for fax, then there may not be any point in buying equipment with a speed of more than 9600 bps (the norm for fax machines). There is a significant price premium for fax-modems with higher than 9600 bps fax capacity.
Smart fax-modems carry their on on-board process - and cost more. Dumb ones use the host computer's processor and are driven by separate software for modem and fax.
A fax-modem may not be as economical as two separate pieces of equipment, each designed to do one thing well. For ordinary users fax-modem is the best option, but if your fax traffic is heavy and time-charged then some research is warranted.
Compression Makes the Difference
Most fax run at 9600 bps, but in modern equipment the data is compressed before transmission. Presently three techniques are used: MH (Modified Huffman), MR (Modified Read), and MMR (Modified Modified Read). The best compression rate is achieved by MMR.
A fax machine treats a document as a graphics image, not text. Horizontal white space compressed particularly well, large black areas yield a much lesser compression rate, and vertical white spaces do not compress as efficiently as horizontal white space. Where a regular format is used for fax it is worth while considering document design for compression efficiency.
Data compression is a different matter; fax-modem driven by software will normally use different compression algorithms for data and fax respectively.
Fax Bureaux
Developments in fax and communication technology have made it possible for fax bureaux (not the newsagent-with-a-fax) to provide efficient, cost effective commercial services, particularly in broadcast faxing, which is not necessarily the same as junk-fax.
Fax-on-demand is well established in North Amenica as a means of obtaining information. There are two kinds, subscription services and free calls. A subscription service would, for example, provide stock exchange information; a free-call service mi€ be provided by a vendor to deliver on-request information (usually technical) about products.
The NSW Department of Agriculture provides a fax-on-demand service. It is not automated, but users can obtain faxed copies of Agfact titles on hundreds of topics, such as enzootic bovine leucosi or beginning in bees.
New Technology
A recent development is the ability to transmit files (including executables) and scanned colour image; by fax. The technology is mentioned in PC Update of Jan-Feb 94. It is not something in development that will will be available real s-o-o-o-n, but is here, now.
Literature
Fax has become ubiquitous, particularly as it is now available to ordinary PC users. Little, however, has been published, even in the professional/technical/ reference field.
The only current publication I know of is Fax Power, written by Philip Sih who has been involved in the development of products including interactive fax equipment, online communications services, and data communications products.
It covers a wide range of topics including fax broadcasting and fax-on-demand; computer-driven fax; how fax works; fax performance (problems, getting the best results, factors affecting transmission speed, etc.); fax document design; digital direct fax output methods; integration of fax into traditional DTP packages; and a directory.
The book is a valuable resource for those who use fax for more than just pushing documents through, regardless of how they come out at the other end. How often have you received a fax that is close to unreadable, skewed, streaky, lines dropped out, and so on? Well, give a thought to how your faxes arrive. If presentation is important, then Fax Power is recommended reading.
Commercial users of fax should certainly make Fax Power available to staff responsible for preparing and carrying out fax transmissions. Managers who read it will find much to improve their understanding of what fax can do, and are sure to see prospects for productive innovation.
Fax Power (ISBN 0 442 01207 1) is easy reading with a minimum of technical jargon. Mysterious terms, when used - such as ECM (error correction mode) - are explained.
The book is published by Van Nostrand Reinhold and has an RRP of $54.95.
Reprinted from the April 1994 issue of PC Update, the magazine of Melbourne PC User Group, Australia
