INTERNET ACCESS

One of the most challenging aspects of the Internet is selecting a connection. Although most subscribers begin with dial-up connection, many soon explore high-speed Internet options. Home based LANs and wireless Internet access have become very popular.

A dial-up connection uses POTS (plain old telephone services) to transport data between your computer and your ISP. With a dial-up connection, your computer’s modem essentially places a regular telephone call to your ISP, when the ISP’s computer “answers” your call, a dedicated circuit is established between you and your computer. This circuit remains connected for the duration of your call and provides a communication link that caries data between your computer and the ISP.

The modem, you use with this type of connection, converts the signals from you computer into signals that can travel over the telephone lines. The word “modem” is derived from the words “modulate” and “demodulate”. In communication terminology, modulation means changing the characteristics of a signal, as when a modem changes a digital pulse into an analog audio signal. Demodulation means changing a signal back to its original state, as when a modem changes an audio signal back to a digital.

Another option for Internet connection is cable Internet service; with it your cable TV company becomes your Internet provider. In order to provide this type of connection, satellite dishes are installed; usually they are installed for a community and are referred to as the head-end. From the head-end, a cabling system branches out, offering both television and Internet access. Bandwidth of each cable is divided among three activities: TV channels, downstream data (the data you receive) and upstream data (the data you send).Cable Internet service plans offer speeds up to 6 Mbps.

With this connection your computer becomes part of a neighborhood data network and in this case two issues become significant: bandwidth and security. Unlike a dial-up connection, cable Internet service provides an always-on connection, which is particularly vulnerable to hackers and virus attacks. As for the second issue, the cable you share with your neighbors has a certain amount of bandwidth, and as more people use the service, it might seem to get slower and slower.

Other options, such as DSL and ISDN, could be chosen to get a high-speed Internet access. DSL (digital subscriber line) is a high-speed, digital, always-on, Internet access technology that runs over standard phone lines. It is one of the fastest Internet connections that’s affordable to individual consumers. Several variations of this technology exist, including ADSL (asymmetric DSL, with downstream speed faster than upstream speed). DSL is digital, so data doesn’t need to be changed into analog form and then back to digital as it does when you use a dial-up connection. A DSL can simultaneously carry voice and data, if permitted by DSL provider.

ISDN (Integrated Service Digital Network) is an all digital service with the potential to simultaneously carry voice and data. ISDN is not fast as DSL or cable Internet service but faster than a dial-up connection. A device called an ISDN terminal adapter connects a computer to a telephone wall jack and translated the computer’s digital signals into signals that can travel over the ISDN connection. ISDN service is typically regarded as a high-speed Internet connection option for businesses that maintain small LANs.

There are two primary options for getting a wireless access of your home PC or LAN to the Internet: satellite Internet service or fixed wireless Internet service. Satellite Internet service uses a satellite to transmit computer data directly to and from a satellite dish, owned by and individual. A satellite modem connects the satellite dish to a computer. In many areas, satellite Internet service is the only alternative to a dial-up connection. But on the downside, satellite data transport is subject to latency delays of one second or more, which occur as your data is routed between your computer and the satellite that orbits the Earth 22.200 miles above the Earth. Satellite transmission and reception can be blocked by adverse weather conditions, which make this type of data transport less reliable than most wired options.

Fixed wireless Internet service is designed to offer Internet access to homes and businesses by broadcasting data signals over areas large enough to cover most cities and outlying areas. Wireless technologies have less latency than satellite Internet service and can offer connection speeds suitable for online gaming and teleconferencing.

Also it is possible to connect to the Internet through LAN. LAN provides a cost-effective way to share one Internet connection among several computers. School computer labs and businesses usually provide access over LANs. LAN Internet access is also feasible for home networks. A single cable Internet, DSL, ISDN, or satellite connection can be cabled into your home LAN and accessed by all its workstations.

Comprehension check. Indicate the paragraph where the following ideas are found in the text.

1. If a TV company has necessary equipment it can act as an Internet provider.

2. A lot of people soon switch from dial-up they use at the beginning to other types of connection.

3. If it’s allowed by provider, DSL can transmit both voice and data.

4. Satellite Internet service depends on the weather conditions.

5. With cable Internet service your computer is always connected to the Internet.

6. One of the cheapest ways to share Internet connection is LAN.

Vocabulary practice

1. Match up the words that are opposite in meaning.

always-on relaxing

outlying insecure

challenging favourable

feasible unstable

reliable close

adverse unsuitable

2. Fill in the blanks choosing from the variants given.

1. With a dial-up connection, a modem … the signals from your computer into signals that can be carried over the phone lines.

a) converts b) passes c) spreads

2. Using a satellite Internet service you can meet with … delays of a second or more.

a) established b) latency c) elapsed

3. When a modem changes the characteristics of a signal it means that … is carried out.

a) transformation b) modulation c) conversion

4. If you choose cable Internet service you should remember that it provides an always-on connection that makes your PC … to viruses and hackers.

a) protected b) unseen c) vulnerable

5. In a dial-up connection, modem places a call to your ISP and you are remained connected with it for the … of you call.

a) duration b) whole c) most part

6. One of the most popular options to have high-speed Internet access is ADSL. In it … speed is slower then … speed.

a) downstream a) upstream

b) initial b) downstream

c) upstream c) terminal

3. Make three-word combinations using the words in columns and then fill in the gaps in the following sentences.

A: wireless B: communication C: speed

home terminal circuit

suitable Internet LANs

established connection adapter

SDN based access

provide dedicated link

1. Satellite Internet service is one of the options of getting … .

2. If you like to play online computer game it’s advisable for you to get fixed wireless Internet service since it can offer … for online gaming.

3. Recently … have become one of the most popular way of getting Internet access.

4. With a dial-up connection, when the computer of ISP ”answers” the call of your computer’s modem, you get so called … between you and ISP.

5. To translate the computer’s digital signal into signals that can travel over the ISDN connection you need a device called … .

6. An established dedicated circuit is used to … that caries data between the subscriber’s computer and ISP.

4. Fill in the gaps in the text.

A cable modem provides Internet access over the TV cables that carry television signals from the cable company’s ___ to your home. With this connection two issues become significant: security and ___.

With ___ connections, such as DSL and cable, the ___ can enter the Internet any time his computer is turned on. ___ Internet service provides another high-speed Internet access method, but it has higher latency ___.

Nowadays you can get Internet access through LANs. Besides, LAN is considered to be really ___ way to share one Internet connection among several computers.

Speaking. Discuss the following questions.

1. How does a modem work?

2. What is the significance of becoming part of a “neighborhood network”?

3. What is DSL?

4. What are options for wireless Internet access?

5. What are the pros and cons of satellite Internet service?

Text C

Pre-reading. Match the meaning of the following English words and their Russian equivalents.

Reading. Read the text and try to guess the meaning of the words in bold. Check your variants in the dictionary.

Date: 2015-01-12; view: 1642