Satellite systems Revision Notes

Satellite systems use artificial satellites orbiting the Earth to transmit data and signals over vast distances. These systems enable services that are difficult or impossible to provide through terrestrial networks alone, especially in remote or inaccessible areas. Satellites operate by receiving, processing, and relaying signals between ground stations and user devices, supporting applications in navigation, communication, and geographic data analysis.

• Satellites orbit Earth to cover large geographic areas.
• They transmit signals for navigation, communication, and data collection.
• Satellite systems complement terrestrial networks, extending reach.

GPS is a satellite-based navigation system that provides precise location and time information globally. It consists of a constellation of satellites continuously transmitting signals containing their position and time. A GPS receiver calculates its location by measuring the time delay from multiple satellites, using trilateration.

Satellite navigation systems use GPS data to assist vehicles, ships, and aircraft in route planning and real-time positioning. For example, a car’s navigation system uses GPS to show its current location on a map and suggest the best route to a destination.

• GPS satellites broadcast signals with position and time data.
• Receivers calculate location by measuring signal travel time from at least four satellites.
• Satellite navigation helps in transport, logistics, and personal navigation.
• Example: A ship uses GPS to avoid hazards and plot a safe course.

GIS combines satellite imagery and other spatial data with software tools to analyse and visualise geographic information. Satellite data provides up-to-date images and measurements of the Earth's surface, which GIS uses for applications such as urban planning, environmental monitoring, and disaster management.

For instance, city planners use GIS to map land use and plan infrastructure development, while environmental scientists monitor deforestation using satellite images integrated into GIS.

• GIS integrates satellite images with mapping software for spatial analysis.
• Applications include urban planning, agriculture, and environmental monitoring.
• Satellite data provides real-time or periodic updates for accurate decision-making.
• Example: Tracking flood-affected areas using satellite imagery in GIS.

Satellite television delivers broadcast signals directly from satellites to home receivers, bypassing the need for extensive cable networks. This allows access to a wide range of channels even in remote locations.

Satellite communication systems also include satellite phones, which enable voice and data communication where terrestrial mobile networks are unavailable, such as in remote wilderness or during natural disasters when ground infrastructure is damaged.

• Satellite TV broadcasts signals over large areas without cables.
• Users receive signals via satellite dishes connected to receivers.
• Satellite phones provide communication in areas lacking mobile coverage.
• Example: Emergency responders use satellite phones in disaster zones.

Satellite systems offer extensive coverage, enabling services in remote and rural areas where terrestrial infrastructure is limited or absent. They support diverse applications from navigation to media broadcasting.

However, satellite systems have drawbacks. The initial cost of launching and maintaining satellites is high. Signal transmission can experience delays due to the long distances involved, and weather conditions like heavy rain or storms can interfere with signal quality. Additionally, obstacles such as tall buildings or dense forests may block signals, reducing reliability.

• Advantages: global coverage, accessibility in remote areas, supports multiple applications.
• Disadvantages: high setup and maintenance costs, signal latency, weather interference, and signal blockage by obstacles.
• Example: Satellite TV signal may degrade during heavy rainstorms.