21st november 2014
 Iphone – texting-internet-appswhen texting it sends wirelessly to
the reciver
 Laptop-downloading-internet- it
travels using cables to download
from the internet to the computer
 House phone- calling- it travels
wirelessly to another phone buts
connected to cables
 Texts – to talk to people- Messages
are delived wirelessly
 Snapchat – to snap peopleMessages are delived wirelessly
 Facebook – to message -Messages
are delived wirelessly
 Data exchange is all methods of
passing data between devices
components and users over a
network.
 Data is anything you can send eg:
pictures, texts , videos, audio.
 Devices are phones, tablets ,
printers.
 Voice over internet protocol
 Voice and video over the internet
 You need webcam, speakers,
microphone.
 Voice is encoded then decoded on
the other computer called codec.
 The program digitalises your voice
signal and turns in into internet
packets and reverts it at the other
end.
 Wireless communications use radio
waves or infrared.
 your device needs a wireless
interface card to have wireless
connection.
 The card is used to transmit data to
and from the network.
 Unshielded twisted pair
cables are basic pairs or
cables twisted together
 Shielded twisted pair cables
are the same but with a foil
shield
 Max data – 250Mbps
 Max range – 100m
 Benefits twisting cancels out
some interference and low
cost
 Limitations, slower, less
capacity than others and can
only be used for short
distances
 E.G. analogue telephone
network
Solid wire separated
from a copper outer by
a plastic insulated sheet
The inner cable
transmits data and the
outer connects to the
earth
Max data – 1000mbps
Max range – 100m
Fast&reliable
Cost more than utp/stp
Eg. Connection to tv
network
Glass or plastic cables
which uses internal
reflection of lite to transmit
data. Normally uses led or
laser visible light
Max data – 2.4gbs
Max range – 50km
Fast, long distances
Complex connections and
equipment needed
Eg. Fiber optic broadband,
connects to bt panels in the
street then uses coaxial
cables to the house.
Short range data transmition that
uses infared light
Max data – 4mbps
Max range – 100m
Short range, must be in line of sight
Reliable
Tv controls and some phones
 Short wave length radio transition
and a very high frequency
 Max data – 300gbps
 Max range – 100m
 Signal dose not degrade over long
distances
 Divice must be in line of sight, is
affected by weather
 Bluetooth
satellite
Satellite is used for TV transitions, connects to tv channels via
The satellite.
 Data is transmitted from earth to a
satellite which relayed it back to
another station on earth
 Max data – huge
 Max range – 500km/36,000km
 Expensive
 Global communication
 Distance and speed
 Sends data in only 1 direction
 Radio broadcasting
 Sends data in both directions
But only one at a time
Maximise band with
 Sends data in both directs at the
same time
 telephone
 Data is transmitted simultaneously
Over an equal number of wires and
cables.
Allows the data to be transmitted
together so you don’t have to wait
because its sent at the same time
Max of 5 meters because it has a
short range
Used to be used to connect printers
to your computer but now its only
used for a small number of things
because its to costly and the range is
only 5 meters
 Transmitting in both directions
 Fiber optic used this technology at
the same time using 2 cables not 1
 Bits are transmitted one at a
time over a single channel
 This reduces the cost of the
cable but gives a slower rate
of transfer
 They have to be
disassembled into individual
bits for transmition then
reassembled at the other end.
 Can be used over large
distances.
 Universal sereal bus
 Sends data one bit at a time
 Introduced to make it easy to
import to several devices
 All devices that use usb
 Xbox
 Charger
 Memory stick
 Satnav
 Computers
 Tvs
 Typically, a client is a computer
application, such as a web browser,
that runs on a user's local
computer or workstation and
connects to a server as necessary.
 Could result in viruses
 Typically, a server is a computer
program, such as a web server,
that runs on a remote server,
reachable from a user's local
computer or workstation. If you
have no computer how are you
going to charge it up? You need to
have good connection
 Client side processing:
 This is Taking place on the
computer.
 Interactive features on a webpage
are downloaded on to the
computer and then processed
away from the web server
 The website code (web script) is
interpreted by the web browser
different browsers may translate
the code differently
 Game is downloaded on webpage,
you do not sent to or from server it
all happens just on the webpage
and YOUR computer and no were
else.
 Advantages;
 Quicker because it hasn’t got to go
to and from the server.
 Speed, fast to connect and
download quickly
 Security, not comment to hacks or
bugs.
 Disadvantages;
 Browser specific, can only show up
the way you want it on certain
browsers
 Computer speed, the computer
may not be fast even though your
software is faster.
 Server side:
 Data is sent back and forth from
server and computer
 Because the processing is done on
the web server it don’t matter
about which browser you use.
 An example of this would be
completing an online form as the
results are processed and stored
on the server.
 Advantage:
 Doesn't matter about web
browser, browser independent.
 Speed does not matter.
 Disadvantage;
 Relies on the server, the server can
over load if to many people are
using it
 Security, can be intercepted much
easier bc its not staying on your
computer