Satellite Systems (Cambridge International IGCSE ICT)

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

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

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

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:

Final answer: 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]