# The Ultimate GPS Quiz

2 min
Image: Klaus Vedfelt/The Image Bank/Getty Images

No one likes to be lost. The Global Positioning System (GPS) is the modern successor to maps, start positions and landmarks, all of which help us find our way on land or sea. Developed by the U.S. military, the GPS is actually a constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). Take this quiz to learn more about using the GPS.
Which method was used by our ancestors to know where they were on Earth?
positions of stars
smoke signals
flags

They used the position of the stars to know their location. They also used landmarks and created detailed maps to help them know their bearings.

Which part of the US government developed the GPS?
federal reserve
military
judiciary

The U.S. military developed and implemented the 27-satellite GPS network as a military navigation system, but soon opened it up to everybody else.

How much does each GPS satellite weigh?
8,000-10,000-pounds
5,000-7,000-pounds
3,000-4,000-pounds

On average, each GPS satellite weighs about 3,000-4,000 pounds (1,361-1,814 kilos).

How many times does a GPS satellite rotate each day?
two
three
four

A GPS satellite does two rotations each day.

At any given time, how many GPS satellites are "visible" in the sky from any location on Earth?
three
four
five

The orbit of each GPS satellite is arranged so that, at any given time, there are at least four satellites "visible" from anywhere on Earth.

What is the name of the mathematical principle used to calculate your location based on information from the four GPS satellites?
pentalateration
trilateration

The mathematical principle is called trilateration. Using this, a GPS receiver locates the four GPS satellites, figures out the distance to each, and uses this information to deduce its own location.

What form of trilateration is used to calculate your location on land?
2-D trilateration
3-D trilateration
4-D trilateration

2-D trilateration calculates your location on land.

What form of trilateration is used to calculate your location in space?
2-D trilateration
3-D trilateration
4-D trilateration

3-D trilateration calculates your location on space.

What is the speed of radio waves?
46,500 miles per second
93,000 miles per second
186,000 miles per second

Radio waves are electromagnetic energy, and thus travel at the speed of light, which is about 186,000 miles per second in a vacuum (300,000 km per second ). GPS receivers receive and analyze high-frequency, low-power radio signals from the GPS satellites.

What do you call the long, digital pattern sent by GPS satellites at a fixed interval?
pseudo-random code
Da Vinci code
omega code

Every day, at fixed time, the GPS satellite sends out a long, digital pattern, which is called pseudo-random code. The GPS receiver uses the lag between the time when the code is sent and the time it receives the code to determine the distance between itself and the satellite.

What type of clock do all GPS satellites have?
digital clock
atomic clock
quartz clock

All GPS satellites contain an atomic clock, which is extremely accurate. However, it is very expensive, costing around \$100,000 apiece.

What type of clock do all GPS receivers have?
digital clock
atomic clock
quartz clock

All GPS receivers contain an ordinary quartz clock, which is constantly reset. The receiver receives the incoming signals from four or more satellites and calculates its own inaccuracy, that is, the difference between the set time of the atomic clocks inside GPS satellites and the far cheaper quartz clocks that all receivers have. This way, GPS receivers are able to enjoy the accuracy of atomic clocks.

What does a GPS receiver use to know where each GPS satellite will be at any given time?
almanac
calendar
timesheet

The GPS receiver uses an almanac, which is updated constantly by the US Department of Defense. The almanac tells the receiver where every satellite should be at any given time.

What variety of GPS deals with the inaccuracy caused by radio signals bouncing off large objects such as skyscrapers?
incremental GPS
differential GPS
augmented GPS

It is called Differential GPS (DGPS). DGPS helps correct errors caused by radio signals bouncing of large objects. It also deals with incorrect almanac data (position of GPS satellite).

built-in mp3 player
built-in torch
built-in maps

When GPS receivers have built-in map files in memory, it makes them more user-friendly. This way they are then able to guide your way through a terrain effortlessly by mixing the position data and the locations on the map. Some GPS receivers will also let you download detailed maps into memory or supply detailed maps with plug-in map cartridges.

What do you call the process used to improve the reception of your GPS receiver?
initializing
rebooting
restarting

The process is called initializing. You need to perform receiver initializing only one time, and the GPS will hold this information in its memory. Keep in mind that each GPS model has a different method for initializing, so you should check your owner's manual.

When should you not rely on a GPS?
There is pitch darkness all around you.
There are less than four satellites on the screen.
There is no moon in the sky.

If the GPS signal is weak, or you find that there are fewer than four satellites on the screen, you shouldn't rely on GPS. Instead, you should navigate using a map and compass.

What function of the GPS receiver you can use during outdoor activities such as camping?
power-save
snooze
waypoints

Use the waypoints function. Waypoints are basically points that you can enter into the memory of your GPS for a particular journey. You can designate various stops along the journey as waypoints; for example, motel, gas stations, conveniences, rendezvous points and so on.

What function of the GPS receiver you can use to see all the waypoints on a journey?
go-to
waylist
way-to-go

Use the go-to function to find out about all the waypoints that will appear on your screen. Select the waypoint you want and the GPS receiver will immediately let you know how far away it is and what direction you need to travel to get there.

Which important GPS-receiver skill helps you track your path on complex trails so that you don't get lost on the way back?