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

ICT 0417 – 6 ICT Applications: Satellite Systems (Deep‑Dive)

1. Syllabus Context – Where This Note Fits

The Cambridge IGCSE/A‑Level ICT syllabus (0417) is divided into 21 content areas. This hand‑out concentrates on the sections that relate to satellite systems while also providing the missing foundational material required for a complete AO1‑AO3 coverage.

2. Core ICT Foundations (Syllabus Sections 1‑5)

2.1 Computer Hardware – Input, Output & Storage

• Central Processing Unit (CPU) – Executes instructions; measured in GHz.
• Memory – RAM (volatile, fast) and ROM/Flash (non‑volatile).
• Storage devices

  • Hard Disk Drive (HDD) – magnetic, high capacity.
  • Solid‑State Drive (SSD) – flash, faster access.
  • Optical media (CD/DVD/Blu‑ray) – archival.
  • Cloud storage – remote servers accessed via the Internet.

• Input devices – Keyboard, mouse, touch screen, scanner, GPS receiver, digital camera.
• Output devices – Monitor, printer, speakers, projector, satellite dish (LNB).

2.2 Software – Operating Systems & Applications

• Operating Systems (OS) – Windows, macOS, Linux, Android, iOS; manage hardware resources.
• System software – Device drivers, utility programmes.
• Application software – Word processors, spreadsheets, databases, GIS, navigation apps, video‑conferencing, satellite‑TV decoders.
• Software licensing – Proprietary vs. open‑source; relevance to copyright (see § 5).

2.3 Data Representation & Processing (Brief)

• Binary, hexadecimal, and ASCII/Unicode character sets.
• Data types – integer, floating‑point, Boolean, text, image (raster) and vector.
• Basic processing – input → processing → output; algorithms expressed as flowcharts or pseudocode.

2.4 Communication & Networking (Including Satellite Media)

• Network types – LAN, WAN, MAN, Internet, Intranet, Extranet.
• Transmission media – Copper (twisted pair, coaxial), fibre‑optic, wireless (Wi‑Fi, Bluetooth), satellite links.
• Key protocols – TCP/IP, HTTP/HTTPS, SMTP, FTP, VoIP (SIP).
• Satellite as a communication medium – Provides coverage where terrestrial infrastructure is absent; used for TV broadcast, broadband, and voice (see § 7).

3. Systems Life‑Cycle (AO2)

A systematic approach ensures that ICT solutions meet user needs and are maintainable.

1. Analysis – Gather requirements, identify constraints, conduct feasibility study.
2. Design – Produce specifications, data models, UI mock‑ups, and flowcharts.
3. Development / Implementation – Write code, configure hardware, install software.
4. Testing & Evaluation – Unit, integration, system, and acceptance testing; collect feedback.
5. Documentation & Maintenance – User manuals, training material, update plan.

Case Study (mini‑example): Designing a student‑attendance system for a school.

• Analysis – teachers need to record attendance quickly on tablets; data must be stored centrally.
• Design – ER diagram (Students, Classes, Attendance), UI wire‑frames.
• Development – Android app + MySQL server.
• Testing – pilot with one class, collect error reports.
• Documentation – quick‑start guide, online help; schedule quarterly updates.

4. Safety & Security (AO3)

• Physical safety – Secure mounting of satellite dishes, avoid high‑gain antenna exposure, use insulated tools.
• E‑safety – Protect eyes and ears when using satellite phones, avoid prolonged exposure to strong RF fields, follow safe‑working‑at‑height procedures.
• Data protection

  • Encrypt GPS‑derived location data (e.g., AES‑256).
  • Use secure protocols (TLS/SSL) for satellite broadband and email.
  • Apply the principle of least privilege to GIS databases.

• Common threats & mitigation

  • Jamming – Deploy anti‑jamming filters; switch to alternative GNSS constellations.
  • Spoofing – Use multi‑GNSS receivers with integrity monitoring (SBAS, GBAS).
  • Signal interception – End‑to‑end encryption for satellite‑phone calls.
  • Malware & phishing – Keep firmware up‑to‑date, use reputable anti‑virus, educate users.

5. Audience & Copyright (Communication)

• Audience analysis – Identify the knowledge level, purpose and preferred format (e.g., technical report for engineers vs. infographic for the public).
• Copyright & licensing

  • Software – respect EULA, differentiate between free‑ware, share‑ware and open‑source.
  • Satellite imagery – most commercial data are licensed; many public datasets (Landsat, Sentinel) are under Creative Commons or public‑domain licences.
  • Content creation – attribute sources, avoid plagiarism.

• Netiquette for satellite services

  • Use concise subject lines in satellite email (bandwidth is limited).
  • Avoid large attachments; use cloud links where possible.
  • Be patient with latency – especially on LEO broadband and satellite phones.

6. ICT Applications Overview (Section 6 of the syllabus)

Each sub‑topic is listed with a one‑sentence purpose, a key feature and an example task.

7. Satellite Systems – Core Content (AO1, AO2, AO3)

7.1 Global Positioning System (GPS)

Characteristics

• Constellation: ≥ 24 Medium‑Earth‑Orbit (MEO) satellites at ~20 000 km altitude.
• Frequencies: L1 = 1575.42 MHz, L2 = 1227.60 MHz (civilian L2C for higher accuracy).
• Provides 3‑D position (lat, long, altitude) + precise time.
• Civilian service is free; military signals are encrypted.

Uses

• Navigation for road, air, and maritime transport.
• Land surveying, cadastral mapping.
• Location‑based services (mobile apps, emergency dispatch).
• Timing for telecom networks, power‑grid synchronisation, financial trading.

Advantages

• Global coverage (except extreme polar regions).
• Civilian accuracy 5–10 m; ≤ 1 m with augmentation (WAAS/EGNOS).
• Instantaneous updates (≥ 1 Hz).
• No ground‑based infrastructure required for the end‑user.

Disadvantages

• Signal loss in urban canyons, dense foliage, indoors.
• Reduced geometry at high latitudes → lower accuracy.
• Vulnerable to jamming and spoofing.
• Requires line‑of‑sight to at least four satellites for a full solution.

7.2 Other Global Navigation Satellite Systems (GNSS)

Key Constellations

• GLONASS (Russia) – 24 MEO satellites, comparable accuracy to GPS.
• Galileo (EU) – 24 MEO satellites; free high‑precision service (~1 m) and a commercial encrypted service.
• BeiDou (China) – 35 satellites (MEO, GEO, IGSO); includes short‑message capability.

Uses

• Precision agriculture – auto‑steering tractors.
• Geodesy – monitoring tectonic plate movement.
• Search‑and‑rescue – emergency beacons transmit GNSS coordinates.
• Autonomous vehicles & drones – high‑rate positioning.

Advantages

• Redundancy – loss of one system does not cripple service.
• Improved geometry and availability when using multi‑GNSS receivers.
• Centimetre‑level accuracy possible with RTK or PPP augmentation.

Disadvantages

• More complex and expensive receivers.
• Some premium services (e.g., Galileo Commercial) may require subscription fees.

7.3 Geographic Information Systems (GIS) – Satellite‑Based

Characteristics

• Data sources: Optical (Landsat, Sentinel‑2), Radar (Sentinel‑1), hyperspectral, commercial high‑resolution (WorldView, PlanetScope).
• Data models: Raster (pixel) and vector (points, lines, polygons).
• Core functions: Spatial queries, overlay analysis, network routing, suitability modelling, change detection.
• Software: ArcGIS, QGIS, ENVI, Google Earth Engine (web‑based).

Uses

• Urban planning – land‑use mapping, infrastructure monitoring.
• Environmental monitoring – deforestation, glacier retreat, flood extent.
• Disaster management – rapid damage assessment, evacuation route planning.
• Transport logistics – route optimisation, traffic analysis.
• Public health – disease‑outbreak mapping, health‑facility accessibility.

Advantages

• Visual, spatial perspective aids decision‑making.
• Can cover regional to global extents with consistent data.
• Frequent satellite revisits enable near‑real‑time monitoring.
• Integrates non‑spatial data (demographics, economics) for richer analysis.

Disadvantages

• High cost for very high‑resolution commercial imagery.
• Specialised software licences and training are expensive.
• Large data volumes demand substantial storage and processing power.
• Accuracy depends on sensor resolution, atmospheric correction and geometric correction.

7.4 Media Communication Systems

7.4.1 Satellite Television

• Orbit: Geostationary Earth Orbit (GEO) ≈ 35 786 km; satellite appears stationary over the equator.
• Frequency bands: Ku‑band (12–18 GHz) – most common; Ka‑band (26.5–40 GHz) – high‑throughput services.
• Transmission chain: Uplink (ground station) → GEO satellite → downlink → parabolic dish → Low‑Noise Block downconverter (LNB) → set‑top box (decoding).

Uses: Broadcast TV to homes, hotels, ships, remote communities; pay‑per‑view, subscription, interactive services (e‑PGM, VOD).

Advantages: Wide coverage (single GEO satellite can serve a continent), HD/4K quality, works where cable/fibre are unavailable.

Disadvantages: Rain fade (signal loss in heavy precipitation), precise dish alignment required, one‑way broadcast leads to higher latency for interactive services (~250 ms round‑trip).

7.4.2 Satellite Phone

• Orbits: Low‑Earth Orbit (LEO, 600–2 000 km) – Iridium, Globalstar; Medium‑Earth Orbit (MEO, 8 000–12 000 km) – Inmarsat.
• Frequencies: L‑band (1.5–1.6 GHz) for voice; S‑band (2–4 GHz) for data.
• Service model: Handset ↔ satellite ↔ gateway ↔ PSTN or IP network.

Uses: Voice and low‑rate data in remote or disaster‑affected areas; maritime, aviation and expedition safety (e.g., EPIRB beacons); field reporting for journalists and scientists.

Advantages: Near‑global coverage (including oceans and polar regions), independent of local infrastructure, rugged hardware.

Disadvantages: High cost per minute (£0.50–2.00) and expensive handset; limited bandwidth (≈ 100 kbps) – not suitable for video streaming; signal blockage by dense foliage, mountains or indoor environments.

7.5 Emerging Satellite Technologies (AO1)

• LEO broadband constellations – Starlink, OneWeb, Project Kuiper. Thousands of small satellites deliver 100 Mbps – 1 Gbps internet with latency < 30 ms.
• Satellite Internet of Things (IoT) – Narrow‑band IoT (NB‑IoT) and LoRa via LEO satellites for remote sensor networks (wildlife tracking, precision agriculture, environmental monitoring).
• Hybrid GNSS‑IoT devices – Combine GNSS positioning with satellite‑IoT uplink for asset tracking in areas without cellular coverage.

8. Practical ICT Skills (Section 9‑21 Overview)

Although the focus of this hand‑out is satellite systems, the following ICT competencies are required for the full syllabus.

• File Management – Creating, naming, organising, backing up, and version‑controlling files and folders.
• Spreadsheets – Formulas, functions, charts, data‑validation, and simple macro (VBA) automation.
• Databases – Tables, primary/foreign keys, queries (SQL), forms and reports.
• Presentations – Slide design, multimedia integration, animation, and presenter notes.
• Website Authoring – HTML/CSS basics, use of templates, publishing via FTP or web‑hosting services.

9. Evaluation Checklist – Applying Knowledge (AO3)

When asked to recommend a satellite technology for a specific scenario, use the following checklist:

1. Identify the user requirements (coverage, accuracy, bandwidth, cost, latency).
2. Match requirements to the characteristics of each system (GPS vs. multi‑GNSS, GEO TV vs. LEO broadband, etc.).
3. Consider advantages (global reach, high‑resolution data, low latency) and disadvantages (rain fade, signal blockage, expense).
4. Assess safety & security implications (jamming risk, data encryption, physical installation hazards).
5. Evaluate the environmental & audience factors (e.g., remote community, emergency responders, commercial broadcaster).
6. Conclude with a justified recommendation, citing at least two strengths and one limitation of the chosen technology.

10. Quick Reference Table – Satellite Systems at a Glance

11. Summary

This hand‑out now provides a complete, syllabus‑aligned overview of:

• Fundamental ICT concepts (hardware, software, data, networking).
• The full systems life‑cycle and safety/security considerations.
• Communication etiquette and copyright awareness.
• A concise catalogue of all ICT application areas.
• In‑depth knowledge of satellite‑based technologies – GPS, other GNSS, GIS, satellite TV, satellite phones, and emerging LEO services.
• Practical ICT skill areas required for the exam.

Use the evaluation checklist and quick‑reference table to answer AO3 questions that ask you to judge the suitability of a satellite system for a real‑world problem.