GPS is basically a global positioning system used to locate a GPS receiver, which will receive in three-dimensional space anywhere you might be on earth. GPS is controlled by 21 active orbiting satellites at almost 12000 miles above the Earth. The GPS navigation system is designed to have multiple tracking satellites at any given point on Earth. Ground control stations and spare satellites complete the full global tracking system. GPS navigation is probably one of the most astounding inventions to help mankind in so many different applications. An example of GPS you might not have thought of is parcel-tracking delivery by truck, ocean liner guidance systems; airlines right down to hikers to golf cart GPS. The reason GPS navigation is so widely used is because of the very rapid and high degree of accuracy, which can be used in all weather conditions and any time you need it no matter where you are on earth. With the use of transmitted radio signals from satellites your GPS receiver has the ability to find your position within 50 feet (15 m). GPS software is used to take the information and evaluate the position of the GPS receiver. There is a very basic principle that is used from the gps receivers that is it reads signals from multiple satellites and places at least three positions on the ground taking a barring and draw a line through three points then you'll know exactly where you are globally positioned. There are a few limitations that may hinder your calculations. First the GPS navigation receiver should have a clear view to the sky in order to receive data. Radio microwave signals travel in straight lines just the same way light waves do. You will find anything solid will block your signal such as a canyon wall or even trees. Any weather conditions like snow or rain will not interfere with a satellite signal.

How does a GPS unit work?

The GPS navigation unit is all based on precise time measurement. All satellites that are used for GPS positioning and tracking have several atomic clocks on board their systems. It all starts with the satellite transmitting exact time radio signals that your GPS receiver will pick up on. The satellite radio signal delivers precise time to information, giving the GPS receiver exact timing when the satellite sent the signal. The GPS navigation unit onboard database computer uses this measurement of time in transit; at the same time the satellite will send a transmission navigation signal and will tell the GPS software their exact position. With this information in your GPS receiver it will calculate the distance from the satellite and give you your GPS navigation system location on a spherical surface, which is known as (map datums). A GPS device then links to more satellites and will complete the same procedure where the three points meet and show where the GPS navigation unit is positioned. By acquiring a signal from a fourth satellite will just refine your global position.

What to look for and a GPS unit

·Signal loss:. Canyons and caves at any tall buildings will hinder your readings. You will be able to minimize this if you use a system that continuously monitors multiple satellites at a time

GPS software: check the GPS software and what if any restrictions it may have. Is it good for mapping, is it economical, will the program lasts for more than a couple years.

GPS power supply: how long will the battery last, GPS units draw a lot of power if left on continuously. Check to see if it has an AC adapter input.

GPS/maps/directions: look at the mapping capability and how it is displayed on your GPS unit. Can you upload old mapping from your PC. Will it work if you travel outside your country? Will this mapping system last several years as markets change rapidly.

GPS and durability: check to see and how water resistant the unit is. Also look at the shockproof design to see how rugged it is. Temperature limits have a big impact on GPS units as they don't work well under extreme temperatures.

GPS navigation can be used in several different areas

There are several different uses that you could use a GPS unit. On the road in a car, hiking the wilderness out in the water or even in the air. All of these areas can be sub categorized to more specific uses depending on your specific GPS needs. Looking for a vehicle tracking GPS realize that these units need to have some reasonable accuracy and be reliable. They must contain road maps detailing areas that you want. Remember the satellite is only used for transmitting and timing of global positioning informational data and don't send actual area maps data, that is up to your GPS navigation unit to calculate. There are portable GPS devices that you can quickly install in the vehicle for the same use. You can always acquire a handheld GPS unit and be portable and on the move anywhere you need to be. One more is the Marine GPS, which uses very specific GPS mapping software programs because it needs to use information differently it also should be water resistant to protect itself.