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A Facsimile (FAX) machine is a device to copy a document and
send the image, or facsimile, across the network to a similar
device at the receiving end, where a copy is reproduced onto
paper or into a PC. Sending documents in this way is quicker
than postal services and since pictures can also be sent more
efficient than verbal descriptions. This saves time and money
as the information transfer is immediate and action can be
taken on the document in all but the most sensitive circumstances
when originals are required. In recent time Fax and now email
have become the preferred means of communication in business,
after the telephone.
The document is scanned and digitised to become a bitstream
(series of 0’s and 1’s) which is then encoded and
control information added for transmission across the network
using a modem. At the receiving end the control information
is used to recreate a copy of original document. The scanning
and encoding may be performed live once a connection between
the two machines is established, which is why documents are
sent in sections, each is coded transmitted and reception
confirmed before the next part is sent.
FAX equipment is divided into groups depending upon its type.
In general terms these are Group 4, digital (I.431) able to
connect directly to the digital network; Group 3 the current
standard for connection to the analogue network and the older
groups 1 and 2, now discontinued, for the analogue network.
Group 4 can communicate with Group 3 machines; Group 3 can
communicate with some Group 2 of which there are still some
in service; Group 1 can only communicate with other Group
1 machines.
Common FAX features include:
| Copy |
The ability to scan and copy locally, doubling
as a light use photocopier. |
| Broadcast |
The same document can be stored and sent
to multiple destinations automatically. |
| Memory Dial |
Frequently used numbers can be stored and
dialled using abbreviated codes. |
| Memory Store |
Received documents are held in the machine
memory if the paper runs out. |
| PC Transfer |
Received faxes are transferred to a PC or
office network for on screen viewing |
| Print / Scan |
The fax machine doubles as a printer / scanner
for a connected PC |
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