Friday, June 24, 2011

Modem


Introduction
Modem is short for modulator-demodulator. Modems are required so that various computers can communicate with each other over a network. They convert the analog signals, which a computer receives over a telephone or cable television line into the digital signals.

When the use of Modem began in 1970’s most of them were used to connect computers to a Bulletin Board Systems (BBS). Initially 300 BAUD Modems were used which could transmit 30 characters per second. But nowadays modems available in the market transfer the data at a much faster rate thus allowing you to download huge amounts within few minutes

Types of Modem

  • Dial-up Modems- These modems were widely used in the late 1990’s. Dial-up modems used standard telephone line to connect to the Internet Service Provider (ISP). When developed these modems had the data transfer capability of 56 Kbps but the major drawback of using the dial-up technology was that a user couldn’t use telephone line while using the Internet.
  • Cable Modems – These types of modems allow computer systems and networks to communicate over the cable television infrastructure networks. These networks use co-axial cable media to communicate. Cable modems are generally used for broadband based Internet access.
  • Wireless Modems – Wireless modem is a network device which connects to wireless network. It attaches directly to your notebook or a computer. Wireless modem interfaces include Compact Flash, USB and Serial Port.
  • Voice Modems- Voice modems are just like standard modems that are capable of recording or playing audio over the telephone line. They are used for telephony applications.
  • ADSL/DSL Modems – ADSL stands for Asymmetric Digital subscriber line. However unlike dial up one can receive and make phone calls while simultaneously using the Internet. The reason why this is termed as asymmetric is because while using the ADSL modems user has much higher download speeds as compared to the upload speed.
On the other hand DSL (Digital Subscriber Line) modems give equal speed while both downloading and uploading the content on the Internet.
Modem

Introduction

Modem is short for modulator-demodulator. Modems are required so that various computers can communicate with each other over a network. They convert the analog signals, which a computer receives over a telephone or cable television line into the digital signals.

When the use of Modem began in 1970’s most of them were used to connect computers to a Bulletin Board Systems (BBS). Initially 300 BAUD Modems were used which could transmit 30 characters per second. But nowadays modems available in the market transfer the data at a much faster rate thus allowing you to download huge amounts within few minutes

Types of Modem

Dial-up Modems- These modems were widely used in the late 1990’s. Dial-up modems used standard telephone line to connect to the Internet Service Provider (ISP). When developed these modems had the data transfer capability of 56 Kbps but the major drawback of using the dial-up technology was that a user couldn’t use telephone line while using the Internet.
Cable Modems – These types of modems allow computer systems and networks to communicate over the cable television infrastructure networks. These networks use co-axial cable media to communicate. Cable modems are generally used for broadband based Internet access.
Wireless Modems – Wireless modem is a network device which connects to wireless network. It attaches directly to your notebook or a computer. Wireless modem interfaces include Compact Flash, USB and Serial Port.
Voice Modems- Voice modems are just like standard modems that are capable of recording or playing audio over the telephone line. They are used for telephony applications.
ADSL/DSL Modems – ADSL stands for Asymmetric Digital subscriber line. However unlike dial up one can receive and make phone calls while simultaneously using the Internet. The reason why this is termed as asymmetric is because while using the ADSL modems user has much higher download speeds as compared to the upload speed.

On the other hand DSL (Digital Subscriber Line) modems give equal speed while both downloading and uploading the content on the Internet.

What is Ethernet


Ethernet is a computer networking technology primarily used for Local Area Network (LAN). It was invented by Robert Metcalfe in 1970’s while he worked at Xerox.

In LAN architecture you have, two or more computers connected with each other and sharing resources such as Internet, fax, scanners etc. Each computer or a workstation has a NIC (Network Interface card). This NIC is connected to Ethernet cable which in turn is connected to the central hub or a Local server, which directs all the communication processes and enables sharing of resources.

Initially Ethernet used twisted pair or co-axial cables to connect to the Internet or a network. CSMA/CD (carrier Sense Multiple Access/ Collision Detection) technology was used to transmit the data and it employed the use of co-axial cable for this transmission. But nowadays Ethernet uses full duplex transmission via twisted copper cables or fiber optical cables.

Ethernet is the most popular LAN protocol and has evolved over the period of time. When invented its data transmission capability was few Mbps like 10 Mbps but now we have Ethernet cables with data transmission capability of over 1000Mbps or it is called as Gigabit Ethernet. In fact Ethernet cables with capability of 10Gbps have now been introduced. The length of the cable used may vary depending upon the usage. It may be few meters in length or might spread over entire school and universities campuses.

The formal standardization of Ethernet by IEEE (Institute of Electrical and Electronics Engineers) is known as IEEE 802.3

Ethernet Cable

Though we have been seeing increase in wireless network platform but still Ethernet is a faster, reliable and secure source of internet connectivity.