PCs & Peripherals
Build To Order
Monitors / LCDs
CD / DVD Burners
Hard Drive Enclosures
Memory / RAM
Motherboards and CPUs
Digital Picture Frames
iPod & MP3 Players
Flash Memory Cards
Ink & Toner
Keyboard / Mice Input
Security & Surveillance
USB Flash Drives
Global Positioning System (GPS)
GPS stands for Global Positioning System - At the end of the 1970's, the United States Department of Defense (DoD), conceived a system which allowed any element of the military (planes, ships, submarines, tanks, ground forces) to know their position precisely and instantaneously, anytime and anywhere on the earth's surface. The Global Positioning System (GPS) was built to fulfill this task.
In essence, the GPS system is made of a constellation of satellites constantly orbiting the earth, at an average altitude of 20,000 kms, scattered on 6 equally spaced orbital planes. As a result, at least three satellites are always visible at anytime from anyplace on the surface of the earth. Each satellite emits a coded signal, which contains essential GPS Navigation/GPS Location information - like its position and the exact timing of the signal emission to earth. Therefore, only a simple receiver is needed to measure the elapsed time between emission and reception of the signal. The satellite to station distance is simply deduced from this travel time.
Three different measurements made on three different satellites give the three distances needed to determine the three coordinates of the station (GPS systems) position (the location of the receiver): latitude, longitude, and altitude. This type of measurement is known as "pseudo-range" measurements in GPS jargon. Every satellite emits two types of pseudo-ranges: A precise code (P code) which enables a position precision of around 10 meters and a coarse code (C/A code) which allows a precision of around 100 meters. The precise code is encrypted and restricted to the U.S. military receivers. Civilian applications are based on the pseudo-ranges measurements is this of the C/A code. However, even using the C/A, incredibly precise location positions are possible for every day use.
GPS Navigation Systems
There are three main types of GPS devices available for consumer and commercial use: GPS Navigation; GPS Tracking; and GPS Location.
GPS Navigation (such as Garmin GPS or Magellan GPS Navigation Systems) is used to help you see where YOU are right now, and to help you get from Point A to Point B. There are numerous devices made for GPS Navigation, from hand-held units, to those that are installed in cars and commercial vehicles, from manufacturers such as: Garmin, Magellan, TomTom, DVS/Synchrome, Harman Kardon, InVion, Mio, Navigon, Pharos, and more. These are basically mapping systems. Each has very limited recording (tracking) capability, and generally do not have the ability to create and upload detailed logs of vehicle travel. Many businesses have already invested in mapping systems to increase productivity by improving route planning, and personal navigation systems are becoming wide-spread. You can also get a GPS receiver that you can use with your portable computer and software mapping system to provide GPS mapping right you're your personal computer, from makers including: Deluo and Microsoft.
GPS Tracking is used to precisely record a log of all vehicle (or personal) activity and travel over an extended period of time. GPS Tracking is useful in eliminating time-consuming and poor quality vehicle use logs; as well as, increase productivity, and accountability, by maximizing business use of your vehicles, while decreasing or eliminating personal use. They are also great to keep track of where the kids have been. The best units provide second by second tracking for the highest accuracy of position AND speed traveled, while having built-in motion sensors so data is only collected during actual travel allowing for much longer recording.
GPS Location is used to provide Real-Time positioning of a vehicle or the GPS device, so you know where it is right now. These usually provide minimal tracking capability or none at all, and are not a replacement for GPS Tracking. GPS Location is mostly used for fleet vehicles, emergency location positioning, or as an aid in recovery of a vehicle or asset. GPS Location involves "Pinging" the device via satellite or by cell phone, and having it "phone" home with its current position via satellite cellular technology. This means that there is a recurring cost for GPS Location, that does not usually apply to GPS Tracking.