How GPS Receivers Work

GPS Units make sure you know where you are goingyour location. A series of spheres line the distance
no matter where you are. Gone are the days offrom one place to the next, based on the location of
getting lost easily. A GPS system can cost under $100the satellites at the time of the transmission to the
for a less-than-fancy model. However, what your GPSGPS receiver. The spheres intersect and meet and as
Unit looks like is not as important as what it actuallythe distances from different locations on different
does.spheres are measured, your exact location is
The GPS receiver is a handheld, sometimes portablepinpointed. All of the four satellites' plots work together,
device that works with the Global Positioning Systemto intersect in one place through the spheres.
(GPS) network. The GPS network is comprised of 27GPS receivers generally try to use more than four
satellites that constantly orbit the earth. As the earthsatellites at one time. This provides a more accurate
rotates, so do the satellites. Of these 27, 24 of thelocation and less room for error. The Earth is also used
satellites actually work, while three are used asas a marker, which works with the GPS network to
backups. As you can imagine, running the GPS is quitehelp pinpoint locations on the surface of the planet.
costly.GPS receivers have to know how far a distance it is
The GPS network was originally developed by thefrom the satellite to the unit. To do this, radio signals
United States military. The military used it to increasesent from the GPS satellites are analyzed. These
navigational accuracy. However, it was not long beforesignals are high in frequency though they are relatively
the GPS network was open for use by anyone.low in power. The better your GPS unit is the better
How it works is simple. First, the satellites have multiplechance you have of using multiple satellites in order to
orbit routes around the earth. At any one moment inpinpoint your exact location.
the day, at least four of the satellites are able toSince radio signals travel at the same speed light does,
transmit information from the satellites to GPSGPS receivers are able to determine how fast the
receivers. Of course, it is imperative that the viewwaves travel and how far they have traveled. At
between the satellite and the GPS unit is unobstructed.random times, the satellites transmit pseudo-random
That is why GPS receivers sometimes do not workcode, which are digital patterns, to the GPS receivers.
right in areas with high mountains, a lot of trees, orThe GPS unit will then play the digital pattern, though
skyscrapers in the way.there will be a lag. This lag is based on how fast the
GPS receivers work with the satellites. First, the GPSsignal traveled, and is a major part of the GPS plotting
hunts down four of the satellites that can connect withprocess.
and transmit information to the GPS unit. Once fourIn order to track the signal's pattern, the satellite and
satellites have been found, the distance to each of thethe GPS receiver use clocks, which synchronize
satellites is recorded, and the GPS can pinpoint itstogether. The Satellite uses an atomic clock, while the
location, by the distance it is from each satellite.GPS receiver uses a regular clock. However, to
This mapping and estimating is based on a principle inaccommodate synchronization, the clock in the GPS
mathematics, which is known as trilateration. How itunit is able to constantly reset. This prevents any type
works is by traveling through three-dimensional space.of clock problems from occurring.
This is complex to understand, but the result isThere are various types of GPS systems. These
amazing, and it should be what you look for whensystems work to fix any inaccuracies and errors in the
purchasing a GPS unit of your own.GPS receiver's location tracker. These systems
Trilaterion that works in 3-D is what is used to mapinclude WAAS and DGPS.