Computer to Computer: Modems

Signals

Two types of signals are used for data transmission:

Digital and Analog.

A digital signal is a stream of 0's and 1's. So this type is particularly appropriate for computers to use.
An analog signal uses variations (modulations) in a signal to convey information. It is particularly useful for wave data like sound waves. Analog signals are what your land-line phone and sound speakers use.

Modems

When communications between computers use the telephone system for at least part of the channel, a device is needed to translate between the analog phone line and the digital computer. Such a device is the modem, which comes from Modulate/Demodulate, which is what a modem does. It modulates a digital signal from the computer into an analog one to send data out over the phone line. Then for an incoming signal it demodulates the analog signal into a digital one.

Though rather small, modems are very complex devices. There are entirely too many commands, protocols, and configuration choices available. Once you get a modem set up and working right the first time, you probably won't have to tinker with it much afterwards. Hurrah!!

Date: 2015-01-11; view: 922