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are then bounced among cell towers until
they are received and converted back to
the sound of your voice at the other end.
That’s why the sound of your voice can
changewhenyoucall different people;some
phones and cell networks are better than
others at transforming the received radio
waves back into the sound of your voice.
Radio waves are also the core science behind Global Positioning
System (GPS) technology.Most users probably don’t think twice
when they access an application like Google Maps. However,
when you type in an address and search for directions, it’s not
your phone or your car that’s providing the answer it’s a network
of some two dozen satellites orbiting the Earth that are doing the
work. Each GPS satellite is essentially a big radio transmitter
sending a signal that includes the satellite ID, orbital informa-
tion, and a very precise atomic clock time stamp.A GPS receiver,
such as the one in your smartphone or in your car’s navigation
system, processes the radio waves sent from the satellites and
uses a mathematical formula to calculate the receiver’s current
location. Currently, the systemuses between 27 and 32 satellites,
with some being used as backups in case of failure.
Navigation is the most obvious product of the GPS satellite
network. Today, nearly every form of transport, from ships to
planes to the family car, uses GPS to navigate.Beyond navigation,
the applications that have sprung forth fromGPS technology are
mind-boggling. GPS is vital for many military uses, such as the
precise targeting systems used by missiles. Geologists use GPS
An inside look at how Global
Positioning Systems work
Science and Information Technology
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