1.5 Compare and contrast transmission media and transceivers
Wireless Media
📘CompTIA Network+ (N10-009)
What is Satellite Communication?
Satellite communication is a type of wireless transmission media that uses satellites orbiting the Earth to send and receive data signals between two or more locations on the planet.
Instead of using cables or ground-based antennas, data is transmitted through radio waves to a satellite in space, which then relays the signal back down to another location on Earth.
This allows communication over long distances, especially in areas where physical cables or cellular towers are not available.
🌐 How Satellite Communication Works
- Uplink – The signal is transmitted from a ground-based station (called the earth station) to a satellite.
- Satellite Relay – The satellite receives the signal, amplifies it, and changes its frequency (to avoid interference between uplink and downlink).
- Downlink – The satellite sends the signal back to another earth station or receiver on Earth.
- Distribution – The receiving station processes the signal and sends it to the network or end device.
🧩 Components of Satellite Communication
| Component | Description |
|---|---|
| Satellite | The device orbiting Earth that receives, amplifies, and retransmits signals. |
| Earth Station / Ground Station | The base station on Earth that communicates with the satellite using large antennas. |
| Transponder | A component inside the satellite that receives, converts, and sends signals back to Earth. |
| Antenna | Used to transmit and receive signals between Earth and the satellite. |
📡 Types of Satellite Orbits
Satellites can orbit the Earth at different altitudes. Each orbit type affects signal latency and coverage area.
| Orbit Type | Altitude | Description | Latency | Example Use |
|---|---|---|---|---|
| Geostationary Earth Orbit (GEO) | ~35,786 km | The satellite stays fixed over one point on Earth; great for broad coverage. | High (~600 ms) | Broadband, TV, Internet backhaul |
| Medium Earth Orbit (MEO) | 2,000 – 35,786 km | Faster response time than GEO but covers smaller areas. | Medium (~125–250 ms) | GPS, navigation systems |
| Low Earth Orbit (LEO) | 180 – 2,000 km | Close to Earth; low latency and high-speed communication. Requires multiple satellites for coverage. | Low (~30–50 ms) | Internet services (e.g., global coverage networks) |
⚙️ Frequency Bands Used in Satellite Communication
Different frequency bands are used for satellite communication depending on purpose, distance, and weather resistance.
| Band | Frequency Range | Characteristics | Common Use |
|---|---|---|---|
| L Band | 1–2 GHz | Resistant to rain; low data rates | GPS, mobile satellite services |
| C Band | 4–8 GHz | Stable but needs large antennas | Television, data communication |
| Ku Band | 12–18 GHz | Smaller antennas; more affected by rain | Internet, VSAT, broadcast |
| Ka Band | 26–40 GHz | High speed; sensitive to weather | High-speed Internet and enterprise links |
🌍 Satellite Communication in IT Environments
Satellite links are commonly used in IT networking for:
- Remote site connectivity – To connect branch offices, data centers, or remote locations where fiber/copper cannot reach.
- Disaster recovery networks – To maintain communication when terrestrial networks fail.
- Backhaul for ISPs and cellular networks – For connecting remote cellular towers to the main network.
- Global positioning systems (GPS) – To provide location-based services and navigation.
- Maritime and aeronautical connectivity – For ships and airplanes to access the Internet and corporate networks.
⚡ Characteristics of Satellite Communication
| Feature | Description |
|---|---|
| Coverage | Can cover entire regions or continents. Excellent for global communication. |
| Latency | Higher than other wireless media, especially in GEO satellites, due to the long signal distance. |
| Bandwidth | Moderate to high depending on orbit and frequency band. |
| Reliability | Affected by weather (especially Ku and Ka bands) and atmospheric interference. |
| Cost | Expensive setup and operational costs compared to terrestrial options. |
| Mobility | Excellent — provides connectivity for moving platforms such as aircraft or ships. |
🧠 Key Terms to Know for the Exam
| Term | Meaning |
|---|---|
| Uplink | Transmission from Earth to satellite. |
| Downlink | Transmission from satellite to Earth. |
| Transponder | A device in the satellite that receives, amplifies, and retransmits the signal. |
| Footprint | The coverage area on Earth that a satellite’s signal can reach. |
| Latency | The time delay between sending and receiving data. |
| Rain Fade | Signal degradation caused by heavy rain, especially at higher frequencies (Ku/Ka bands). |
🔄 Comparison: Satellite vs Other Wireless Media
| Feature | Satellite | Cellular | Wi-Fi | Microwave |
|---|---|---|---|---|
| Range | Global | Regional | Local | Point-to-point |
| Latency | High (especially GEO) | Low to medium | Low | Medium |
| Bandwidth | Moderate to high | Moderate | High | High |
| Mobility | Excellent | Excellent | Limited | Poor |
| Installation Cost | High | Moderate | Low | Moderate |
| Interference | Atmospheric/weather | Network congestion | Physical obstacles | Line-of-sight required |
🧩 Advantages and Disadvantages
✅ Advantages
- Provides global coverage, even in remote or rural areas.
- Useful for backup or redundancy in enterprise networks.
- Supports mobile and moving devices (ships, planes, vehicles).
- Does not require physical infrastructure like cables.
❌ Disadvantages
- High latency (especially in GEO systems).
- High cost for equipment and bandwidth.
- Weather sensitivity, especially in higher frequency bands.
- Limited bandwidth compared to fiber or microwave.
🏁 Summary for Exam Preparation
- Satellite is a wireless transmission medium that transmits data via radio signals between Earth stations and satellites.
- Key components: satellite, transponder, uplink, downlink, and ground station.
- Three main orbit types: GEO, MEO, and LEO — each with different latency and coverage.
- Used in IT for remote connectivity, backup links, GPS, and mobile communication systems.
- Frequency bands: L, C, Ku, and Ka — each with trade-offs in bandwidth and weather resistance.
- Be familiar with terms like latency, rain fade, transponder, and footprint for the exam.
