What are different communication devices? Types of Modems

What are different communication devices? Types of Modems

The hardware used to transmit data information between a sending and receiving devices is called communication devices. Set sending and send data to a communication channel. Device at receiving and receive data from communication channel. Communication device may also convert the data from digital to analogue and analogue to digital signals.

Modem 
Modem stands for modulator/ the modulator. Used communication device that send and receive data from one computer to another on the internet through telephone lines. The sending and receiving computers both must have modems. Computer stores information in the form of digital signals. The information transmitted over the telephone line is in the form of analogue signals. Receive data from computer in digital form and convert it into analog form. Is called modulation. Analogue signals to other computer using telephone lines Peer gate on receiving Computer Services data in analogue form. Analogue data back into digital form. Is called demodulation.

Types of modem 

1. External modem 
Attached to the system as it is connected to the telephone wall Jack by another cable. It requires external power supply. Easy to setup external modem is expensive.
2. Internal modem 
Internal modem is a circuit board that is inserted into an expansion slot on the motherboard internal modem cannot be moved from one computer to another easily. It is difficult to setup than other types of modem. Expensive than external modem

3. Wireless modem
Wireless modem transmit data signals through the air instead of cable. It is also known as radio frequency modem. It is designed to work with cellular technology and wireless Local area network. Post handheld computers other mobile devices use the wireless modem to connect to the internet wirelessly it can also be used with notebook and desktop computers.

4. ISDN modems
This modems allows digital transmission of data over telephone lines. It is also known as ISDN adaptor. This is the same twisted pair wiring as dial up modem but it can transmit data faster. Sports data transfer rate 1.54 mbps.
5. DSL modem
DSL modem allows digital transmission of data over telephone lines. It is also called ISDN and adaptor. It uses Same twisted pair wiring as dial up modem but it can transmit data faster. Transfer rate of upto 1.54 mbps.

It has two types
1. Asymmetric digital subscriber line: It uses faster transmission downstream then upstream. Frequently used for faster Internet Services. It provides the upload speed of 640 kbPS and download speed of of 8.1.
2. Symmetric digital subscriber line: It used is the same transmission rate for both directions. It transfers data at 83 mbps approximately in both directions.

6. Cable modem
Cable modem is also known as broadband modem. What is a stand alone device connected with the cable to USB port. It send and receive data over the cable television network. Provide fastest internet speed than dial up modem and ISDN modem.

7. Satellite modem
Satellite modem is used to send and receive data using satellite Technology. It is commonly used internet services. Satellite internet services use satellite Technology for downstream data only. Its satellite modem is a little slower than DSL and cable transmissions.