•  What is Cable Internet?

•  How it works?

•  Broadband advantages

What is Cable Internet?

Internet over cable is a technology and service that uses the existing cable TV networks (made up of coaxial cable lines that bring television signals to TV) to bring Internet data to PC or TV at a very high speed. The television and the Internet transmission take place simultaneously on the same cable but at different frequencies. This allows the user to view TV and access Internet at the same time.

How it works

Historically Internet access was made possible using Telephone line as the medium of transfer, using a dial-up modem. As the demand for faster Internet access grew, newer technologies evolved such as Internet access via the Cable Television network. The working group MCNS has established the Data Over Cable Services Interface Specification (DOCSIS) an international standard for internet access via Cable TV Network using Cable Modems. The DOCSIS standard ensures that multi vendor modems can work on any DOCSIS compliant system across the world.



For Cable Internet access on PC, a Cable Modem is required at user’s end. A cable modem is an external device that connects to the computer to provide high-speed data access via cable TV networks. A Cable Modem sends and receives data to and from the Internet by using the existing coaxial cable network. The modem translates cable signals the same way a telephone modem translates signals from a telephone line. Cable modems translate radio frequency (RF) signals to and from the cable plant into Internet Protocol (IP), the communications protocol spoken by all computers connected to the Internet. A cable modem connects to a computer through a device called an Ethernet card (Network Interface Card). This card provides connectivity between the cable and the computer and interprets the signaling from the cable modem so that the computer's software can display it correctly.



For Cable Internet Access on TV, a Set-top box with a built in Cable Modem is required. Besides the Cable Modem, the set-top box has embedded software like a web-browser, email programme and flash-memory. The set-top box usually comes with a wireless keyboard/mouse and is connected to the TV.



Cable TV Networks are high band-with networks i.e. 550 to 750 MHz by their very nature of design. These networks were traditionally built as one way networks carrying 60-100 Cable TV channels downstream i.e. from Headend to the Subscriber. Internet delivery over Cable TV however requires a two-way network since information of selected website, etc. has to be transmitted to the Headend, from where it would be directed to the website of interest. Higher frequencies flow toward the subscriber and the lower frequencies go in the other direction. Hence setting up of a robust two-way Cable TV network is the first requisite before deploying Cable Modems on a Cable TV network.This is done by upgrades to the amplifiers in the cable distribution network etc.

The Internet signals are in the digital domain and these need to be interfaced to the Analog CATV world. This interface is termed Cable Modem Termination System (CMTS) and typically serves 2000 – 3000 Cable Modems and is connected to a high-speed data link. A typical CMTS consists of an Input interface, Router, Cable Modem card and a powerful Microprocessor.

The CMTS resides at the ISP POP, which receives high bandwidth data from the ISP network center as well as Cable TV signal from the Cable TV Head-end.

At the customer premise, a high quality two way splitter is installed on the CATV line, with one output connected to the Cable Modem/ Set-top Box and the second output connected to the TV.

Broadband technology takes advantage of high-bandwidth technology to offer new or enhanced services. Fundamental to the concept of broadband services is the concept of interactivity. Examples of these services include video conferencing, video on demand and interactivity driven content. Also what we will eventually see booming is the home shopping. The ‘touch n feel’ barrier may to an extend be removed with the advancement of multi-media online shopping. The convenience factor will predominantly play a role in services of finance, stock/shares trading, home banking, etc. Another technology that will explode in the near future will be the compression technologies. This will have various ramifications, such as the number of independent video channels distributed over a cable or satellite network can be dramatically increased by using video compression.

With the real-time encoding and compression of data and decoding of data, convergence will hold the key to the future developments. WAP has already become a reality, wireless devices, such as cellular telephones and radio transceivers, can be used for Internet access, including e-mail, the World Wide Web, newsgroups, and Internet Relay Chat. In the future, devices and service systems that use WAP will be able to interoperate. In the future we may also see convergence of equipment, in the home, it is quite possible that a single set-top box, with high-capacity switching into and out of the box, will be able to fulfill all the communications needs of the household.

Welcome to the age of Broadband!