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Facsimile and Electronic
Mail
Facsimile (known as fax) and
electronic mail (known as e-mail) are ways to send documents
without using the conventional mailing system. These two
means of communication have become very popular. The reason
for this popularity is the speed. Both are much faster than
ordinary mail. Telephone lines are used to transmit
information by the use of a modem (short for
modulator-demodulator). The modem converts digital
information from a computer or a fax machine into a sound signal
that is sent along a telephone line. A modem at the other
end of the line changes this signal back to the original format.
A fax machine can send any
document, whether it contains pictures or words. The
document is placed in the machine. It is then pulled over a
strip of bright light where a scanner measures the reflectivity of
the paper. The white areas reflect the light much more than
areas with writing or drawing on them. The information is
recorded in a sequence of numbers. This information is then
sent along a telephone line to the receiving fax machine, where it
is used to make a copy of the original page.
E-mail allows people to
communicate through the computer. A computer uses a modem
linked into the telephone system. Information can be sent
and shown on the receiver's computer screen at once. If the
computer is turned off, the message can be stored in the computer
memory bank for later retrieval.
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