Made for Brindabella Christian College

1. Bandwidth

2. How much data can it carry?
Almost everything can be measured in some way - How tall
are you? How old are you? How clever are you? and so on.
Communcation channels are just the same - there are
ways of describing their most important attributes.
One of those attributes is "How much data can it carry".
This measure is called "BANDWIDTH".

3. What does bandwidth measure?
Bandwidth measures of the capacity of a communications
channel.
Digital Bandwidth is the maximum amount of data that can
travel along a communications channel in a given time.
The smallest piece of digital data is the 'bit' and time interval
is measured in seconds.
And so a sensible measure of data capacity is "bits per second".

4. Bandwidth and the Internet
Machines on the Internet are connected to each other
through a network of some kind.
Most of the computers are connected
by physical cables such as copper
cable or perhaps optical fibre.
However there are alternatives such
as wireless, microwave or even laser.
No matter what the method used, it is the bandwidth of the
communication channel that determines how much data travels over
any given time.

5. Bandwidth and the Internet
If your computer is connected to a remote server somewhere,
what determines the maximum speed of data transfer is the
part of the connection that has the lowest bandwidth - this
becomes the bottleneck.
Quite often the bottleneck is the "last mile" between your house
and the local telephone exchange. This is because the
connection is making use of plain old telephone wires that were
originally designed to only carry voice signals.
Therefore 'bandwidth' determines the overall performance limit
of a network

7. Bandwidth Speed
Modern internet links are measured in Kilobits per second
(Kbps) i.e thousands of bits per second. Or, in Megabits
(Mbps) - Millions of bits per second.
These are the bandwidths of some connections to the
Internet:

8. Bandwidth Speed
• 300 - 9600 bits per second : Early modems
• 56 kilobits per second: Bandwidth of dial-up modem (some
people in remote areas still have to use these)
• 64 - 128Kbps: ISDN, obsolete, replaced by ADSL broadband
• 512kbps - 20Mbps: Bandwidth of most home ADSL internet links
• 20Mbps - 100Mbps: Superfast broadband

9. Summary
• Bandwidth is the measure of the data capacity of a communications
channel
• Bandwidth is measured in bits per second
• It is common to use Kilobits per second (Kbs) and Megabits per second
(Mbs) when describing the bandwidth of modern communication links
such as the Internet
• Bandwidth determines the overall speed of a connection
• The lowest bandwidth in the communication chain between two
computers determines the maximum speed of connection

10. End of Presentation