Home / Computer Networking / What Is a Modem In Computer & Also Discuss Different Types of Modem With The Help of Examples 

What Is a Modem In Computer & Also Discuss Different Types of Modem With The Help of Examples 

Modem stands for modulation or demodulation. It is a communication device & performs input and output functions at the same time, a computer system must have a modem to send or receive data over the internet connection. The basic function of the modem in the computer system is to send data from a computer and on the other side, the computer receives same data from the modem. Now we are going to discuss about the complete functions and types of modem with the help of examples. In these days telephone connection is very common, we see in towns and big cities almost every home is connected via telephone line. You know well computer store information in digital format but data is sent to other places via analog signals as these analog signals have the most prominent properties such as frequency, amplitude time period to stand complete running connection.

Therefore this device performs following two functions.


At the very first it receives data from the computer in digital format, then modem converts it to analog format to send it out over the telephone line, this process is called modulation.


At data goes to the other receiving end in an analog format the modem converts it to digital format in order to computer system understanding, this process is called demodulation.

working of modem

For further more explanation you can observe in above figure, a computer (A) wants to send data to (B) point, at the very first computer (A) sends data in digital form to modem, and then it converts the data into analog form to send via wire to (B) point. But before reaching to the point (B), the data is received by the modem that is directly connected with (B) point.  It converts it to its original digital form to make readable for (B) point computer. The modem that is connected directly with (A) computer is doing the process of modulation. At the other end, the modem that is connected with (B) point is doing demodulation.

Here is the video for better understanding:

Types of Modem In Computer Network:

A modem can be installed internally or externally it up to you what kind of device you needed. Different types of this famous are as follow.

External Modem

External Modem:

The external modem is such kind of modem that is connected out of the computer through a serial cable. It requires easy steps and external power supply as well. It is expensive but it provides fast data transmission speed, that is why it is used in small to big offices to maintain internet connection without any sort of hurdle.


 Internal Modem:

Internal modem

The internal modem is very similar to an electronic circuit board. It is mounted ov

er the motherboard into on expansion slot. It is little hard to make complete setup. It

provides slow data speed, that is why it is used mostly in the personal computer at home and small shops.


 Wireless Modem in PC:

Wireless modem

The wireless modem is the very popular device. It is being used personal computers to the offices level. It transmits digital signalthrough the air without using cable. In this purpose radio f

requency is used that is why it provides very good internet speed. Smartphone and other devices like notebook, desktop computers use this modem to establish internet connection without using wire. So that cellular companies are providing this sort of connection to make internet connection accessible for all.

ISDN Modem:

ISDN stands for (Integrated Services Digital Network), it is completely digital modem. Synchronous or asynchronous data transmission is used to make it faster and reliable. ISDN can be installed in expansion card on the motherboard or connected externally through a wire just like an external modem. It requires particular telephone line as a digital telephone line.

isdn modem

This type of device can communicate only other ISDN modem but provides high speed of data transmission.


DSL Modem:

DSL stands for “Digital Subscriber Line”. It allows transmission over the normal telephone lines. The advantage of this modem is that provides faster data transmission than ISDN.

types of DSL modem

There are two types of DSL that are under,


ADSL Modem:

ADSL stands for “Asymmetric Digital Subscriber Line”; it provides faster downloading speed than the uploading. Generally, up to 640 kbps uploading and 8.1 Mbps downloading. It became popular because of it downloading speed.


SDSL Modem:

SDSL stands for “Symmetric Digital Subscriber”, it is very similar to the ADSL but it provides same data transmission speed in both directions (uploading, downloading).

Generally, 3 Mbps for both directions (uploading, downloading).

Normally, DSL is used under the three miles of “Public Switched Telephone Network” as distance increases the speed of data decreases.


Cable Modem:

The cable modem is a broadband device.  Television cable network is used instead of telephone line. Simply T.V network cable is connected to a personal com

modem with cable

puter system via USB port to establish the internet connection. The benefit is that it provides faster internet connection speed than DSL or ISDN. That is why in this period of time it is much reliable.

Satellite Modem:

It is expensive technology. NO need to wires or any of telephone connection. In this device, satellite technology is used to send or receive data. It knows the high-speed internet connection. This satellite technology is used excessively for down streaming. Comparatively, it is little slower than DSL or cable modem.

satellite modem

Advantages of Modem:

You know modem is very popular device. I these days almost every android mobile user of the world is using this devices by many ways to get benefits.

Under are given few advantages of this famous device

  • It makes to connect each other to many  devices like mobile phones, notepad, laptops etc.
  • It is playing the basic role to make this world as a global village.
  • Internet marketing runs through this device just like connecting each other.
  • In these days so many countries have doing the slogan as “digital Pakistan” , it is because of the modem communication technology.
  • It made our life more easier as we solve problems of each other.
  • It provides the best security system for agencies and many others departments.
  • Now a days there are many builtin modems in different devices that became more easy to configure it.
  • In many palaces the networking system is completely dependent on modems.
  • Inventions of Wifi modems are also very suitable for people as more than 10 people can use only one modem to connect the world.

Error Detection & Correction In Modem:

  • In these days mostly modems have abilities to detect an error. So that we may be able correct one.
  • A bad telephone connection can cause bits of data lost or scrambled.
  • Another simple method is “party Checking”, in this method there must be an odd number of 1 bits in a data word transmitted, if the modem is using the odd party, there must be an even number, if the device is using an even party.
  • Another most commonly used a method is counting the number of data words sent or received, make sure that is the same.
  • New devices also use several standards to perform error control and correction.


If you have any question related to the modem in the computer system, please do not forget to put in the comment section.