How does GPS work?

From its earliest uses in the US military to its role today in vehicle navigation, surveying and transport tracking, GPS has changed the way we travel, work and have fun. It has also become a crucial tool for emergency services, law enforcement officers and the monitoring of convicted criminals. Find out more about how GPS works and how this high-tech science affects your world. High-Tech Science is a series of four books that look at the revolutionary, cutting-edge science that we rely on to run our lives and keep our modern world working. It it closely linked with the Science and Design and Technology curriculums.