What is modem? and How does a modem work?

What is modem?

Modem is a hardware networking device which is used to change Analog Signal into Digital Signal and Digital Signal into Analog Signal.  In computer, data remains in digital form i.e. binary form 0 and 1, whereas in telephone line, data is in analog form.

 Modem is used in computer to convert digital data into analog data.  So that it can be transmitted over the telephone line, the analog data transmitted over the telephone line is converted into digital data so that computers can easily understand it.

 In other words – Modem acts as both an input and output device, which facilitates the transfer of data between devices on the telephone line.

Types of modem –

 There are many types of modems.  They are generally classified based on data transmission and how they are installed.  Let’s learn about the different types of modems:

1. Internal Modem :

 As its name suggests, it resides inside the computer as an expansion card.  It is installed in the slots present in the motherboard.  Nowadays most computers come with such built-in-modems.

 These are slower than external modems but are cheaper.  Since it is part of the circuit board in the computer, it remains fixed and is not portable.  There are two types of internal modems, dial-up and wireless.

2. External Modem :

 It is a small box-shaped device that resides outside the computer.  It is a peripheral device which is connected to the computer using a wire.  These are a little more expensive than internal modems, but definitely faster.

 They are portable and can be connected to different computers.  It is very easy to install, and it also offers high speed data transfer rates.

3. Dial-up Modem :

 A dial-up gives you Internet access through ordinary telephone lines.  These were the first to be used, in which you were able to access the Internet on your computer by dialing a specific number provided by the ISP.

4. DSL Modem :

 DSL (Digital Subscriber Line) uses telephone lines (usually Ethernet cables) to transfer data from one location to another.  These are faster than dial-up but much slower than cable service.  There are three main types of DSL connections: SDSL, VDSL, and ADSL.

5. Cable Modem :

 In cable modem, coaxial cable is used to connect your computer device to the Internet.  In this you do not need to dial-up, you just have to turn on the computer, you are connected to the internet.  It provides you the fastest internet speed compared to other modems.

How does a modem work?

 By now you must have known what is called Modem.  But if you want to know more about it, then let us tell you how it works?  Let us tell you about it.

 Computers understand only digital signals (1’s and 0’s), whereas telephone lines transmit data from one location to another in analog signals.  This means that both of them do not speak the same language.  In such a situation, so that other devices can understand the message sent by a device connected to the Internet, we place a modem between the computer and the telephone line.

 There are two different types of translators in modem – Modulator and Demodulator.  When you send a message from your computer using the Internet, the job of the modulator is to convert the sent digital signal into an analog signal.  After which that signal will be transmitted through the cable and reach the other device.

 Once the signal reaches the other end, it will have to pass through another modem.  This time the demodulator will convert it back into digital form, so that other computers can understand that message.

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