1. Satellite and mobile network communications
ICT IGCSE
Satellite and mobile network communications

2. Objectives:
You should have an understanding of a wide range of work-related IT applications which make use of satellite and/or mobile network technology, including
Mobile phone networks
Embedded Web technology (EWT)
Global positioning Systems (GPS)

3. A network of mobile phone cells
Mobile phone networks
Mobile phones communicate by using towers that are located in many networked cells.
These towers (masts) allow the transmission of data throughout the mobile phone network.
A network of mobile phone cells

4. How the Mobile Phone Network works
Each tower transmits within its own cell
When you get to the edge of a cell the signal gets weaker
This is recognized by the network, so
The phone picks up the signal in one of the adjacent cells

5. MPT and computers
Mobile Phone Technology can now be used by computers to allow internet access.
A USB network device allows the computer to connect to the mobile network. Very convenient BUT
Slow
Expensive
Monthly contract
Download limits apply

6. WAP
early mobile phones could only be used to send and receive calls and SMS.
Wireless Application Protocol allows smaller handheld devices to access cut-down/ simplified web-based content

7. WAP The wireless device has a ‘microbrowser’
Your device connects with a service provider
Your website request is sent to a gateway server
This retrieves the information using HTTP and encodes it as WML

8. EWT
This is an emerging technology that uses the internet in real time to control or interact with a device in the home
The device must contain an embedded microprocessor

9. Uses of EWT
The device can be controlled by an authorised user from a computer anywhere on a network or from a web-enabled mobile phone

10. GPS
Global Positioning satellite systems can pinpoint your location, give directions to your destination and provide information about nearby businesses.
In-car GPS is often referred to as a satellite Navigation system

11. How GPS works
Satellites surrounding the earth transmit data – this includes the satellite’s position and time
Embedded computers receive and interpret these signals
The exact location of the device is calculated based on the data from at least three satellites

12. How GPS works
Satellite 1
Satellite 2
Satellite 3

13. How GPS works The on-board computer contains pre-stored road maps
The phone(or car)’s exact location (based on the satellite positioning) is shown on the map
You are given verbal directions,
eg “turn left in 100 metres” etc
A screen shows your
position in relation to the
road network

14. Advantages of GPS No need to consult maps while driving – safer
Warns about road closures/one way streets etc
Location of speed cameras
Gives fastest route + alternate routes
Useful info eg fuel stations
Estimated time of arrival

15. Disadvantages of GPS
Maps MUST be kept up to date, otherwise they can give incorrect instructions
Loss of satellite signal can cause problems
GIGO – incorrect start/end positions will cause the system to give incorrect information

16. Other features of mobile phones
Accelerometer – senses tilt, orientation, angle
GPS
Touch screen technology
Apps
/internet
Intelligent maps
Memory:
SD (Secure Digital) cards
SDHC (SD High Capacity)

17. Homework
Use all the links to How Stuff Works/ the videos/new stories and make the following notes:
What is GPS?
What can it be used for?
What devices are required for GPS to work properly?
What can affect the accuracy of GPS devices?
What is WAP?
Why is it needed?
What devices use it?