Modems
Getting
on-line To access the Internet you must have a PC, which has a device to
allow data to be transferred via the telephone line. The device required is
a MODEM; this can be either internal or external. The way a modem works is
to convert the signal from your computer into an analog signal to be
transmitted through the telephone line, and converts the incoming signal
into a digital signal. Hence, the process of modulating and demodulation is
where the device received its name the MODEM.
A modem is fed digital
information, in the form of ones and zeros, from the CPU. The modem then
analyses this information and converts it to analog signals, that can be
sent over a phone line. Another modem then receives these signals, converts
them back into digital data, and sends the data to the receiving CPU.
Analog" refers to information
being presented continuously, while "digital" refers to data defined in
individual steps. Analog information's advantage is its ability to fully
represent a continuous stream of information. Digital data, on the other
hand, is less affected by unwanted interference, or noise. In digital
computers, data is stored in individual bits, which have a value of either 1
(on) or 0 (off). If graphed, analog signals are shaped as sine waves, while
digital signals are square waves. Sound is analog, as it is always changing.
Thus, in order to send information over a phone line, a modem must take the
digital data given it by the computer and convert it into sound, an analog
signal. The receiving modem must convert these analog signals back into the
original digital data.
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