Know and understand characteristics, uses, advantages and disadvantages of satellite systems including Global Positioning Systems (GPS), satellite navigation, Geographic Information Systems (GIS), media communication systems (satellite television, sa

6 ICT Applications – Satellite Systems

Learning Objective

Know and understand the characteristics, uses, advantages and disadvantages of satellite systems including Global Positioning Systems (GPS), satellite navigation, Geographic Information Systems (GIS), and media communication systems such as satellite television and satellite phones.

1. Global Positioning System (GPS)

The GPS is a satellite‑based navigation system that provides accurate position, velocity and time information to users worldwide.

• Characteristics

  • Operates with a constellation of at least 24 medium‑earth orbit (MEO) satellites.
  • Provides three‑dimensional positioning (latitude, longitude, altitude).
  • Signal frequency: L1 (1575.42 MHz) and L2 (1227.60 MHz).
  • Free to use for civilian applications.

• Uses

  • Navigation for vehicles, aircraft and ships.
  • Mapping and surveying.
  • Location‑based services (e.g., mobile phone apps, emergency services).
  • Timing for telecommunications and power‑grid synchronization.

• Advantages

  • Global coverage – works anywhere on Earth.
  • High accuracy (typically 5–10 m for civilian receivers).
  • Instantaneous position information.
  • No need for ground‑based infrastructure for the user.

• Disadvantages

  • Signal can be blocked by tall buildings, dense foliage or indoor environments.
  • Accuracy degrades at high latitudes.
  • Vulnerable to jamming and spoofing.
  • Requires line‑of‑sight to at least four satellites.

2. Satellite Navigation (Other GNSS)

In addition to GPS, other Global Navigation Satellite Systems (GNSS) such as GLONASS (Russia), Galileo (EU) and BeiDou (China) provide similar services.

• Characteristics

  • Each system has its own satellite constellation and signal structure.
  • Multi‑GNSS receivers can combine signals for improved accuracy and reliability.

• Uses

  • Precision agriculture – guiding tractors and equipment.
  • Geodesy – measuring Earth’s shape and movements.
  • Search and rescue – emergency beacons transmit GNSS coordinates.

• Advantages

  • Redundancy – if one system is unavailable, others can compensate.
  • Higher positioning accuracy (down to centimetre level with augmentation).

• Disadvantages

  • Complexity of receiver design.
  • Potential for increased cost in high‑precision equipment.

3. Geographic Information Systems (GIS) – Satellite‑Based

GIS integrates spatial data from satellites with attribute data to analyse and visualise geographic information.

• Characteristics

  • Uses satellite imagery (e.g., Landsat, Sentinel) as a primary data source.
  • Combines raster (images) and vector (points, lines, polygons) data.
  • Supports spatial queries, overlay analysis and modelling.

• Uses

  • Urban planning – mapping land use and infrastructure.
  • Environmental monitoring – deforestation, flood mapping.
  • Disaster management – damage assessment after earthquakes or hurricanes.
  • Transportation – route optimisation and traffic analysis.

• Advantages

  • Provides a visual, spatial perspective that enhances decision‑making.
  • Large coverage area – entire continents can be examined.
  • Data can be updated regularly with new satellite passes.

• Disadvantages

  • High cost of specialised software and training.
  • Large data volumes require substantial storage and processing power.
  • Accuracy depends on the resolution and quality of satellite imagery.

4. Media Communication Systems

4.1 Satellite Television

• Characteristics

  • Broadcast from geostationary satellites at \overline{35},786 km altitude.
  • Uses Ku‑band (12–18 GHz) or Ka‑band (26.5–40 GHz) frequencies.
  • Signals received by a dish antenna and decoded by a set‑top box.

• Uses

  • Delivery of T \cdot channels to homes, hotels and ships.
  • Pay‑per‑view and subscription services.

• Advantages

  • Wide coverage – can reach remote or rural areas where terrestrial infrastructure is lacking.
  • High‑definition and interactive services possible.

• Disadvantages

  • Signal can be disrupted by heavy rain (rain fade).
  • Installation of dish and alignment required.
  • Latency is not an issue for T \cdot but limits use for two‑way interactive services.

4.2 Satellite Phone

• Characteristics

  • Operates with low‑earth orbit (LEO) or medium‑earth orbit (MEO) satellites.
  • Provides voice and low‑rate data services.
  • Typical frequency bands: L‑band (1.5–1.6 GHz) and S‑band (2–4 GHz).

• Uses

  • Communication in remote locations (e.g., offshore, deserts, mountains).
  • Emergency and disaster response where terrestrial networks are down.
  • Maritime and aviation safety communications.

• Advantages

  • Global reach – works almost anywhere on the planet.
  • Independent of local infrastructure.
  • Quick set‑up; handset is portable.

• Disadvantages

  • Higher cost per minute compared with cellular calls.
  • Limited bandwidth – not suitable for high‑speed data.
  • Signal may be blocked by dense foliage or inside buildings.

5. Comparative Summary

6. Review Questions

1. Explain why GPS signals are weaker indoors and how this affects accuracy.
2. Compare the benefits of using a multi‑GNSS receiver versus a GPS‑only receiver.
3. Identify two real‑world scenarios where a satellite phone would be essential.
4. Discuss how GIS can assist in disaster management after a major flood.
5. What is “rain fade” and which satellite service is most affected by it?