Реферат по предмету "На английском языке"


Cable Modems Wave Of The Future

Cable Modems: Wave Of The Future? Essay, Research Paper
CABLE MODEMS–Wave of the Future?
If you think about the future, what is the first thing that comes to mind? Well, in the minds of most people the word computer or Internet will come to mind. Since the introduction of PC’s in the late seventies and early eighties, the technology involved in computers has grown exponentially. The internet, which came into widespread use only five or six years ago has grown unimaginably. Anybody can find virtually anything they want over the Internet. The first way to access the internet was through dial up telephone modems brought through ISP’s such as Prodigy, AOL, Compuserv and many other providers. These providers were slow and sometimes you couldn’t even get through the busy phone lines. the phone modem industry has grown greatly since then, but it still has its flaws. ISDN’s have become popular in the business world and provide better service than telephone modems, but they also have their flaws. The wave of the future as far as Internet access is concerned is cable modems. Cable modems are faster, more efficient, more cost efficient and easier to use than any other Internet access that’s ever been introduced.
WHAT IS A CABLE MODEM?
A cable modem is “a device that allows high speed data access (such as to the Internet_ via a cable TV network.” In other words rather than running the Internet through the telephone, it will be run through cable TV.
HOW DO CABLE MODEMS WORK?
There are five main components to the operation of cable modems:
1. the headend
2. the trunk cable
3. the distribution cable in the neighborhood
4. the drop cable to the home and in house wiring
5. the terminal equipment.
It’s really a fairly simple process. A cable modem network is described as a “tree and branch” network. This means there is a main station (headend_ that has a trunk cable that distributes feeder cables to all of the neighborhoods. These feeder cables branch off into drop cables that go into the homes of the individuals, where it is then wired to the terminal equipment.
WHAT ARE THE ADVANTAGES?
There are many advantages to using the modem over a phone modem or an ISDN connection. Ther first advantage and probably the most popular and important to the average consumer is the speed of the modem. How many times have you found yourself staring at you monitor, waiting for your computer to download a file. Those days are over. A good modem in today’s computer is 56Kbps. The cable modems that are being manufactured now range from, at the low end, 500Kbps to, at the high end, 36Mbps. Most of the cable modems being produced right now operate at 1.54Mbps upstream to 10Mbps downstream.
Transfer Rate for a 10Mb File:
MODEM SPEED/TYPE TRANSFER TIME
9.6Kbps telephone modem 2.3 hours
14.4Kbps telephone modem 1.5 hours
28.8Kbps telephone modem 46 minutes
56Kbps telephone modem 24 minutes
128Kbps ISDN connection 10 minutes
1.54Mbps T-1 connection 52 seconds
4Mbps cable modem 20 seconds
10Mbps cable modem 8 seconds
This is a brief example of how fast a cable modem is in comparison to the connections we use today. This doesn’t even include the 36Mbps cable modem that has been introduced. Another advantage is the imporved service that the cable modem provides over the traditional phone modem. The bandwidth of the cable is 6MHz, which is much larger than that of a telephone modem. This allows more Internet lines to be run through it. Most of the producers of cable modems can ensure that no more than 80% of the lines are being used, and if that much is being used then they can open up more unused lines. This would make it where the user would never get a “busy signal” as you do sometimes with telephone modems. Also the cost of the cable modems, especiall in LAN’S AND WAN’s would be much lower. With telephone modems and ISDN connections, consumers are charged for every minute they are online. With a cable modem there is a flat, monthly rate, usually around $40 a month.
THE DISADVANTAGES?
Are there any disadvantages to this? Well there are a couple of minor disadvantages. Since the network would be a “tree and branch” network, any interference in the network would be combined with all other noise and could make for a noisy connection, and with the large bandwidth of the network there will be a little more noise. However, the producers have done something to fight this. They have developed two main modulation schemes, QAM, which sends data at up to 10Mbps and QPSK, which works at up to 36Mbps. The QAM is more popular right now, because it minimizes the noise produced by the network. While the QPSK is much faster, it is “more robust scheme than higher order modulation techniques in a noisty environment.” Also since there are so many different “frequencies” inside the cable, if a noisy connection is detected, it can automatically be switched to one with minimal noise. We may just have to settle for our cable modem being 1000 times faster rather than 3000 times.
COSTS?
The big question that everyone is going to ask is, how much. How can I get this kind of revolutionary service at a price I can afford? You have to look at it overall. It costs around $200 for the modem itself and about $100 to install it. These prices may sound high but when you can pay a monthly rate for unlimited service, you are going to save a lot of money in the long run. This will especially benefit the people in the telecommuting business. Their cost would be approximately three times less than that of an ISBN network of a telephone modem network.
WILL IT CATCH ON?
Will this new technology catch on nationwide as well as telephone modems have? If you ask me, I would say definitely. These modems will probably catch on at first, to LAN’s such as college campuses. These networks will see the greatest advantage in cost. Even if, for an individual user, the cost is a little higher it’s worth it. Plus, after a whil, just like all other computer hardware, the price will go down. The cable modem is definitely the wave of the future. It’s already beginning to catch on in business’s around the world and will soon be just another thing that people are expected to have on their computer
Sources:
SPEED DEMON CABLE MODEM. www.speed-demon.com
BLAZE NET EXPRESS SPEED.
www. yorkconnection.blazenet.net/blazenet/public/blazenetexpress/speed.htm
CABLE MODEMS. www.cablemodems.com


Не сдавайте скачаную работу преподавателю!
Данный реферат Вы можете использовать для подготовки курсовых проектов.

Поделись с друзьями, за репост + 100 мильонов к студенческой карме :

Пишем реферат самостоятельно:
! Как писать рефераты
Практические рекомендации по написанию студенческих рефератов.
! План реферата Краткий список разделов, отражающий структура и порядок работы над будующим рефератом.
! Введение реферата Вводная часть работы, в которой отражается цель и обозначается список задач.
! Заключение реферата В заключении подводятся итоги, описывается была ли достигнута поставленная цель, каковы результаты.
! Оформление рефератов Методические рекомендации по грамотному оформлению работы по ГОСТ.

Читайте также:
Виды рефератов Какими бывают рефераты по своему назначению и структуре.

Сейчас смотрят :

Реферат Языкознание шпоры
Реферат Доходы бюджетов муниципальных образований и пути их повышения
Реферат шпаргалки по заруюежной литературе
Реферат Экзаменационные билеты по латинскому языку
Реферат Языкознание как наука
Реферат Цикл-метод обучения. (Методика преподавания эстонского языка)
Реферат Творческая интеллигенция в годы массовых репрессий. Вадим Козин
Реферат „B„‚„u„}„u„~„p „s„|„p„s„Ђ„|„Ђ„r
Реферат Функциональные стили современного русского литературного языка и их взаимодействие
Реферат Эссе на английском языке (TEN REASONS FOR A TRADITION OF MODERNITY; Made in Britain)
Реферат Афанасьев Павел Александрович Разработка электронного справочник
Реферат Языкознание древней Греции и Рима
Реферат шпаргалки по современному русскому языку. 4 курс.
Реферат Частицы в русском языке
Реферат Тема обманутых надежд в рассказах Чехова