Inside GPS

Inside GPS — page 3 — ACCESS FOR ALL At first the GPS signals that civilians could use were not very good The US government made the civilian satellite signals less accurate than the military ones This is called selective availability The readings could be wrong by as much as a football field The government did this on purpose It wanted the military to have an advantage The government worried that enemies could use GPS technology against the United States Eventually the US government realized the importance of accurate GPS for everyone It stopped the selective availability in 2000 Public GPS became up to ten times better Today anyone with a receiver has access to free and accurate signals GPS is a worldwide navigation system that uses satellites The satellites send signals to receivers A receiver uses these signals to determine its exact location This ability to track location has many helpful uses GPS FOR EVERYONE GPS was invented by the US military The first satellite was launched in 1978 GPS was designed for both civilians and the military to use At first GPS was only used

Inside GPS — page 4 — GPS satellites are built on the ground before being launched into space by the military It guided rockets and missiles to their targets It helped ships navigate and tracked troops on the ground Soldiers used GPS to find their way around new places GPS was made available for public use in 1983 The military still uses it But now more than 3 billion people around the world use GPS

Inside GPS — page 5 — TRANSPORTATION Many people use GPS to help them find their way around Delivery drivers use GPS to locate addresses Trucking companies install GPS units to track their trucks This is how customers can find out when their packages will be delivered GPS can be used to monitor traffic on roads This can help prevent traffic jams and accidents Pilots also use GPS GPS units can tell where a plane is at any part of its flight It can help pilots know the location of nearby planes GPS can even help pilots land planes when bad weather makes it hard to see GPS helps make car and airplane travel safer It is also more reliable than paper maps It can even save lives Ambulances and other emergency vehicles use GPS It helps emergency responders reach the scene of an accident or disaster GPS helps search and rescue efforts find people in trouble

Inside GPS — page 6 — BUSINESS AND FUN Many businesses are helped by GPS Farmers use GPS to plant and manage their crops GPS helps miners construction workers and road surveyors do their jobs Scientists use GPS to track wildlife find changes to the land and predict earthquakes Banks and power companies rely on the accurate time data provided by GPS GPS can be used for fun too Hikers use RIVAL SYSTEMS GPS is not the only satellite navigation system Some other countries have global systems too Most other countries call satellite navigation systems Global Navigation Satellite Systems GNSS The Soviet Union began using a GNSS in 1982 It is called GLONASS It has 24 satellites The Soviet Union later broke up into several countries The largest Russia continues to operate GLONASS today Europe is building a 30-satellite system called Galileo It’s due to be finished in 2020 China is also building a GNSS It’s called the BeiDou Navigation Satellite System BeiDou comes from the Chinese name for the Big Dipper constellation Běidŏuxīng The Big Dipper was often used for navigation before GPS and compasses existed

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