Satellite Systems (Cambridge (CIE) IGCSE ICT)
Revision Note
GPS
What is GPS?
Global Positioning System (GPS) is a satellite system used to track the exact location of an object
GPS uses orbiting satellites to receive, amplify and transmit signals
Radio frequencies are used to communicate between satellites and ground stations
GPS requires a direct line of sight
Case Study
Sat nav in a car
The position/location of the car is calculated using GPS software
Data is transmitted every few seconds
An algorithm calculates the speed/location of the car
The map is updated every few seconds
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GIS
What is GIS?
A geographic information system (GIS) is a powerful computer system that acts as a database for geographic data
Any data that contains a location component can be stored, such as:
Physical features - Rivers, mountains and roads
Man-made - Buildings, utilities (electricity, water, gas)
Social and economic - demographics, crime rates and/or property value
Two main features of a GIS are:
Analyse geographic data to find patterns/trends/relationships
Visualise geographic data using maps (easier to understand)
Examples of where a GIS may be used include:
Assigning closest emergency services to an emergency
Businesses analysing customer demographic, competitors and possible gaps in the market
Tracking deforestation, monitoring pollution and mapping wildlife habitats
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Media Communication
What is media communication?
Media communication is a system of creating, transmitting, storing and delivering media content using a global network of satellites
Media transmission includes:
TV signals
Radio signals
Internet data
Media communication systems can also act as relays, bouncing signals over a large distance, for example:
Broadcasting live events to a global audience
Ensuring a wider reach to geographically hard to reach places
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Worked Example
Modern-day drivers rely less on paper maps and more on satellite navigation systems (satnav).
Describe the inputs, outputs and processing of a satnav when used by a driver to reach a destination.
[4]
Answer
Four of:
Destination is input by driver [1]
Exact position of motor vehicle is continually calculated using GPS [1]
Using data transmitted from 3 / 4 satellites [1]
The on board computer contains pre-stored road maps [1]
The car’s position is displayed on the map/route displayed [1]
The algorithm calculates the route from the current car’s position to the destination [1]
Makes allowances for traffic jams/roadworks [1]
The car system receives regular updates on traffic conditions [1]
Outputs the journey time/ETA of journey/voice output [1]
Calculates the journey time / ETA of journey time [1]
Outputs speed limits/cameras / warning speed limit [1]
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