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

Published by Patrick Mutisya · 8 days ago

ICT 0417 – ICT Applications: Satellite Systems

6 ICT Applications – Satellite Systems

1. Overview of Satellite Systems

Satellite systems use artificial satellites placed in orbit around the Earth to provide a range of services such as positioning, navigation, data transmission and broadcasting. The main types covered in the IGCSE syllabus are:

  • Global Positioning System (GPS)

  • Satellite Navigation (e.g., GLONASS, Galileo)

  • Geographic Information Systems (GIS) that rely on satellite data

  • Media communication systems – satellite television and satellite phones

2. Global Positioning System (GPS)

GPS is a constellation of at least 24 operational satellites that transmit precise timing signals. Receivers calculate position by measuring the time delay from multiple satellites.

AspectDetails
Characteristics24+ satellites in Medium Earth Orbit (≈20 000 km); provides latitude, longitude, altitude; accuracy typically 5–10 m for civilian use.
UsesNavigation for vehicles, aircraft and ships; mapping and surveying; location‑based services (e‑commerce, emergency services).
Advantages

  • Global coverage – works anywhere on Earth.

  • Real‑time positioning.

  • Free to use – no subscription fees.

Disadvantages

  • Signal can be blocked by tall buildings, dense foliage or indoor environments.

  • Accuracy reduced by atmospheric conditions.

  • Vulnerable to intentional jamming or spoofing.

3. Satellite Navigation (Other Systems)

Besides GPS, other nations operate satellite navigation constellations such as GLONASS (Russia), Galileo (EU) and BeiDou (China). They operate on similar principles but differ in frequency bands and coverage.

SystemKey Features
GLONASS24 satellites, full global coverage, higher accuracy at high latitudes.
Galileo30 satellites, civilian‑controlled, offers higher accuracy (≈1 m) and authentication.
BeiDou35 satellites, regional and global services, includes short‑message capability.

4. Geographic Information Systems (GIS) Using Satellite Data

GIS integrates spatial data from satellites with attribute data to create, analyse and display maps. Satellite imagery provides up‑to‑date information for many GIS applications.

AspectDetails
CharacteristicsCombines layers of spatial (e.g., satellite images, GPS points) and non‑spatial data; supports queries, modelling and visualisation.
UsesUrban planning, environmental monitoring, disaster management, agriculture (precision farming), transport routing.
Advantages

  • Provides a comprehensive view of geographic phenomena.

  • Facilitates informed decision‑making.

  • Updates can be rapid when using near‑real‑time satellite feeds.

Disadvantages

  • High cost of high‑resolution satellite imagery.

  • Requires specialised software and training.

  • Large data volumes demand significant storage and processing power.

Suggested diagram: Satellite orbit showing GPS constellation and coverage area.

5. Satellite Television

Satellite T \cdot transmits television signals from an uplink earth station to a geostationary satellite, which then beams the signal back to a dish antenna at the viewer’s premises.

AspectDetails
CharacteristicsUses geostationary satellites (≈35 786 km altitude); frequency bands typically Ku‑band (12–18 GHz) or Ka‑band (26.5–40 GHz).
UsesBroadcast of T \cdot channels, pay‑per‑view services, direct‑to‑home (DTH) distribution.
Advantages

  • Wide coverage – can reach remote or rural areas.

  • High‑definition and interactive services possible.

  • Relatively quick deployment compared with cable.

Disadvantages

  • Signal can be disrupted by heavy rain (rain fade).

  • Requires a dish and receiver – initial equipment cost.

  • Latency is higher than terrestrial broadcast.

6. Satellite Phone

Satellite phones communicate directly with orbiting satellites, bypassing terrestrial mobile networks. They are essential for communication in areas without cellular coverage.

AspectDetails
CharacteristicsOperates in L‑band (1.5–1.6 GHz) or Ku‑band; uses constellations of low‑Earth‑orbit (LEO) or medium‑Earth‑orbit (MEO) satellites.
UsesEmergency services, maritime and aviation communication, remote field work, humanitarian aid.
Advantages

  • Global reach – works where no terrestrial network exists.

  • Reliable in disaster situations when ground infrastructure is damaged.

  • Voice and low‑rate data transmission.

Disadvantages

  • Higher cost per minute compared with mobile phones.

  • Bulky handset and external antenna required.

  • Signal quality can be affected by terrain (e.g., deep valleys).

7. Summary Checklist

  1. Identify the key characteristics of each satellite system.

  2. Explain typical uses in everyday life and specific industries.

  3. Compare advantages and disadvantages, focusing on coverage, cost, reliability and limitations.

  4. Understand how GIS integrates satellite data for spatial analysis.

  5. Recognise the role of satellite communication in media (TV) and emergency services (phone).