Global Positioning System

In what locations can a GPS function?

• On land, but not on the ocean

• In all areas where cell phones work, but not areas without cell coverage

• In areas with marked roads, but not in the wilderness

• Virtually everywhere on Earth

Where can you see lines of latitude and longitude?

• Only on maps

• Along the borders of countries and states

• At the bottom of the ocean

• At the equator and the North and South Poles

If you're at an altitude of 20,000 km, where are you?

• At the North Pole

• In Outer Space

• On top of a hill

• In an airplane

How is a GPS receiver like a standard radio?

• They both receive information from satellites

• They can both be used to calculate your position on Earth

• They're both capable of picking up radio waves

• They both transmit information at the speed of sound

What do radio waves have in common with visible light waves?

• They have the same frequency

• They have the same speed

• They have the same amplitude

• They have the same wavelength

Why are there around 30 GPS satellites orbiting the earth?

• So that four satellites are above the horizon everywhere on earth at all times

• If there were fewer, they'd be overloaded with information from all the GPS devices on Earth

• 15 provide coverage for all the GPS devices on Earth; the other 15 provide backup in case the main ones breakdown

• To provide the power necessary to sendout high-amplitude waves to GPS

The messages sent from satellites to GPS devices are encrypted. What does “encrypted" mean?

• High-frequency

• Slow

• Powerful

• In code

What might happen if your GPS receiver could only contact two or three satellites?

• Your receiver would have absolutely no idea where you were

• Your receiver would only give you a vague idea of your general location

• You'd only be able to use your GPS device in specific areas

• Your GPS device would not have enough power to function

How does a GPS receiver “know" where a GPS satellite is?

• The information is coded in the waves emitted by satellites

• By using latitude, longitude, and altitude to pinpoint its exact location

• By measuring the delay between when a signal is sent and when it's received

• By measuring how powerful the wave is by the time it reaches the receiver