Broadband Internet
Last updated: 27 March 2008.
If you're using a dial-up modem to
access the
Internet,
switching over to broadband (fast, always-on Internet access) will seem
like nothing short of magic. Not only does your Internet access become
many times
faster, but you can use your telephone line at the same time as well
(something you can never do with dialup). Broadband sweeps you from the
dirt tracks to the freeway—and leaves the 21st-century information age
lying at your feet!
Photo (left): A typical broadband modem: the piece
of equipment that lets your computer make a broadband connection to the
Internet.
The long white bar sticking out of the back is a wireless
antenna (aerial). Everything that happens on explainthatstuff.com passes
through this really dependable Netgear machine,
which I found on Amazon.
Talking telephones
Before the Internet came along, the world of computing was a very
different place. There were far fewer computers
and they worked mostly
in isolation or in small groups known as local area networks (LANs).
The Internet has increased the power of people's computers many times
by allowing all these machines to talk to one another and exchange
information via such things as e-mail and file sharing. You might
wonder where the Internet came from; it seemed to take off virtually
overnight. In fact, the vital piece of infrastructure on which the Net
is
built was already in place and had been invented back in the
1860s. I'm referring, of course, to the telephone
system.
When Alexander Graham Bell and others pioneered telephones in the
19th century, their idea was to help people talk to one another over
long distances in "real-time". Although telephone
equipment was designed for carrying sounds, it gradually became obvious
that
the technology had many other uses. During the late 20th century,
for example, many people started using a technology called fax
(facsimile), which transmits printed documents between two electronic
machines, one at either end of a telephone line. When computer networks
began to take off in the 1970s, it was perfectly natural to use the
telephone system to connect them together. But this created an
immediate problem: computers exchange information (data) in a
number-based language known as digital,
whereas the telephone
system had always been designed to handle rapidly changing sound waves
or analog information. How could computers
and telephones be
made to understand each other?
Dial-up details
The answer turned out to be surprisingly simple. If you go on
holiday to a foreign country where you can't speak the language, you
have two choices. One is to shout, wave your hands around, and point
excitedly. A much better option is to get yourself a translator, who
can convert your words smoothly and seamlessly back and forth into the
foreign language. This second approach is the one that computers use
when they want to exchange information over the old-fashioned telephone
network. But instead of using a translator, they use an electronic
"translating" device called a modem.
Photo: A pair of old-style dialup modems.
The dark box on the bottom is a typical 56K dialup modem from the
1990s. On top is a 56K credit-card-sized PCMCIA modem for use in a
laptop.
A modem (which is short for
modulator-demodulator) takes the
digital information that your computer generates and turns it into
analog information (up and down, constantly varying sound waves) that
can travel along the telephone network to another computer somewhere
else. At that other location, there is another modem that converts the
incoming analog information back into digital data that the other
computer can understand. Two computers can have a lengthy conversation
over the
phone, just like two people chatting away, providing there is a modem
at each end of the line to translate the digital information they
generate into analog signals that can travel back and forth along the
telephone line.
When you dial into the Internet, what you are actually doing is
using a modem and telephone line to make a semi-permanent connection
into a
much larger computer network. As your computer dials in, it sends
digital information down the telephone line to a modem at your Internet
service provider (ISP). Once your modem is talking to the ISPs modem,
your computer can use the ISP's computer to access
other computers all over the Internet. Every time you browse a web
site, your computer is making a link to another computer somewhere else
on the planet using your ISP's computer as a stepping stone.
So how is broadband different?
Dial-up is a really inefficient way of linking to the Internet. When
you dial in, your computer telephones your ISP's computer and then hogs
the line for the duration of the call (in other words, for as long as
you're online). No-one can call you on the phone while you're online.
And even though your computer is hogging the entire line, your modem
and the ISPs modem exchange
information at very low speeds—at best, approximately 56Kbps (roughly
56,000 bits or binary ones and zeros) per second. If you're trying to
download MP3 music
tracks or digital photos, you'll
know this is grindingly slow
and tedious. A single music track can take half an hour or more to
download.
Broadband works a completely different way. Instead of treating your
phone line as a single, narrow pipe between your computer and the ISP's
computer, like a dialup connection, it divides the line into many
different channels. Information can travel in parallel streams down
these
channels. It's like
dividing a highway into several lanes: lots more traffic can go down it
in parallel than down a single-lane road. This is why broadband is so
much faster than dialup. An
average broadband line, working at 512Kbps, is about nine times faster
than the best dialup connection, while a really fast broadband line,
working at up to 8MBps (megabits per second), can
be over 100 times quicker!
Most people download far more information than they upload
(browsing web pages is almost exclusively downloading—because most of
the data is flowing into your computer from the Net), so broadband
allocates more channels to downloading than to uploading. This is why
broadband computers download several times faster than they upload. In
other words, downloading and uploading are not equivalent or
"symmetrical" processes: they are asymmetric. That's why the technical
name for this type of broadband is Asymmetric Digital Subscriber Line
or ADSL. Another type of broadband called DSL allows
uploading and downloading at the same speed.
That just leaves one more question: how can you talk on the phone
while your computer is simultaneously sending and receiving data?
Simple. Some of the channels on the line are reserved for phone calls.
People's voices use relatively low-frequency sounds, compared to the
higher-frequency signals that computer modems use, so it's relatively
easy to keep the phone signals separate from the computer data.
Switching over to broadband
If you're currently a dialup Internet user and you want to switch to
broadband instead, you'll need some slightly different equipment.
First, you'll need to have your telephone line tested and upgraded to
broadband. This is a simple process that your ISP will arrange when you
order broadband for the first time. In the UK, it takes typically five
working
days.
Photo (right): An ADSL microfilter splits the
incoming phone line into two parts, one for broadband Internet and the
other for your phone. The incoming phone line plugs into the left side.
The outgoing ADSL modem and telephone lines plug into the right side.
Next, you'll need a new ADSL modem or router to connect your
computer to your ISP's broadband system. An ADSL modem looks much like
a dialup modem and simply allows one computer to make one broadband
connection. Think of it as a translator plugged into your computer,
just like a dialup modem. A router is
slightly different. It
looks similar to a modem, but
it's a self-contained little computer
whose job is to act as a go-between: it links your home network to the
outside
world. Most routers let you plug several different computers (and other
things like printers) into them. So if you have five PCs at home that
all need Internet access, you can use one router instead of five
separate modems. You can connect a computer to a router in two ways,
either by plugging it in with a cable or by making a wireless
connection. To make a wireless connection, both your router and your
computer need to be capable of wireless networking (they must have
wireless networking cards, aerials, and so on).
If you intend to use your telephone at the same time as your
broadband Net connection, you'll need some little
plastic boxes called microfilters. As their
name suggests, they
filter out the broadband traffic so you don't hear it screeching away
in your ear when you're making a phone call.
Mobile broadband
If you want to find out more about high-speed mobile, wireless broadband (broadband Internet access using a USB modem to connect to a cellphone network ), please see our separate article on
mobile broadband.
Photo: Mobile broadband with a USB modem is an increasingly popular form of wireless Internet.
Further reading
You might find these related articles on our website helpful:
Go shop
