Rex Turner - GPS Engineer / GPS Consultant
GPS is your eye in the sky...
GPS stands for Global Positioning System. GPS is a
satellite based system which was originally considered to be complete when it had 24 satellites. Now the "constellation" is always kept closer to 32 satellites. There are also ground monitoring stations. GPS positions are calculated precisely from signals received from a minimum of 3 satellites. GPS satellites orbit the earth at approximately 12,600 miles in outer space.
This system is used by both the military and the general population. The military system is a more precise version of the same system that the rest of us get to use. Today we have low cost GPS receivers that are in handheld units, fish locators, aviation products, car navigation units and even cell phones.
Typical handheld GPS units are very low power today & can run for days on 2 AA batteries. They are designed primarily to be used out in wilderness areas where there are no roads. They in general are useful for straight line navigation and while they may show roads, do not usually have turn-by-turn capabilities to give you street directions. They are good to find your way back to the car if you are lost in the woods, though!
The most popular category, by far, is automotive products. Automotive products, also referred to as PNDs (personal navigation devices) combined with extensive mapping data can tell you how to get from where you are to where you want to go. It will tell you which street to turn on and how far until you have to turn.
More to come...