Satellite Navigation Systems

- Overview

Satellite navigation is a system that uses a network of orbiting satellites to provide users with their geographic location, velocity, and time information. 

A receiver on the ground, like a smartphone or car GPS, receives signals from multiple satellites and calculates its position through a process called trilateration, using the time it takes for the signals to arrive. 

This enables applications like route guidance and tracking.   

A. How satellite navigation works: 

1. Satellite Constellation: A system, officially called a Global Navigation Satellite System (GNSS), consists of a constellation of satellites orbiting the Earth. The GPS system is one example.
2. Signal Transmission: Satellites continuously transmit signals that contain information about their location and the precise time the signal was sent.
3. Receiving Signals: A satellite navigation receiver on the ground picks up these signals.
4. Position Calculation: By measuring the time it takes for the signals to arrive from at least four satellites, the receiver can calculate its position on Earth.

• The signals from three satellites are used to calculate a user's longitude, latitude, and altitude.
• A fourth satellite is needed to correct for the time difference between the precise time of the satellite's clock and the receiver's less precise clock.

5. Applications: Satellite navigation technology is used for many applications beyond basic navigation, such as mapping, tracking, and time synchronization for things like cell phone towers.

B. Examples of satellite navigation systems:

• GPS (Navstar): The United States' system.
• GLONASS: Russia's system.
• Galileo: The European Union's system.
• BeiDou: China's system.

[More to come ...]