Global Positioning System
Imagine finding yourself lost on a hiking trail in the Appalachian Mountains. How do you get back to where you started your (1) excursion? Nowadays, if you have a smart phone, you can open up a Global Position System (GPS) app, and discover your (2) approximate location. But how does GPS actually work? What is some of the technology that goes into tracking your whereabouts through a cell phone?
The GPS is a satellite-based system established by the United States’ government. It is used both for determining the locations of new points of reference on the ground and for finding someone’s position relative to a map. When, for example, a hiker turns on a GPS (3) receiver (a smart phone or a car device), the receiver accesses at least four satellites that collect coded data. This information is then used to determine the receiver’s approximate location on Earth.
The GPS was developed in the U.S. in the early 70’s to (4) overcome the limitations of previous navigation systems. However, the U.S. isn’t the only country that maintains a worldwide system like the GPS. Russia has developed its own system known as the Russian Global Navigation Satellite System or GLONASS. China is developing the BeiDou Navigation Satellite System or BDS. The European Union is in the process of establishing what they have termed Galileo, after the Italian astronomer Galileo Galilei. India is also taking part in GPS market with its Indian Regional Navigational Satellite System or IRNSS.
So, no matter who is developing these systems, one thing is for sure; we can feel safe knowing that even if we get lost in the Himalayas, somewhere there are satellites controlled by some government that will help us find our way back to a more (5) familiar place.
According to context, the word “approximate”, bolded after the (2) in the first paragraph, is closest in meaning to
