What Is a Modem?

In this tutorial, we are going to see What Is a Modem?

A modem is a device used to transfer information between several computers (2 at least) via telephone lines. Computers work digitally, they use binary language (a series of zeros and ones), but modems are analog. Digital signals go from one value to another, there is no middle, no half, it is All Or Nothing (one or zero). Analog on the other hand does not evolve “by steps”, it covers all values. So you can have 0, 0.1, 0.2 … 1.0 and all intermediate values.

The modem converts the binary information from the computer into analog. It then sends this new code down the telephone line. Weird noises can be heard if you turn up the sound coming from the modem.

Thus, the modem modulates digital information into analog signals; in the opposite direction, it transcribes data in analog form into digital data.
 

 
This is why modem is the acronym for MOdulator/DEModulator.
 

 

Connecting via the telephone line

A telephone line is designed to work with a telephone, which is why a modem needs to establish communication with a remote computer using a telephone number before it can exchange information. A protocol is a language used by computers to communicate with each other. The two most used protocols are :

• the PPP protocol
• the SLIP protocol

 
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