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What is Global Positioning System – GPS?
At the end of the 1970s, the US Department of Defense (DoD) conceived a Global Positioning System (GPS), to determine exact location of military forces via the technique of trilateration.
The GPS system is made of 6 satellites constantly orbiting the Earth, at an average altitude of 20,000 kms. At least 3 satellites are always visible from any place on the Earth. Each satellite emits a coded signal containing GPS Location information. A receiver is needed to measure the elapsed time between the signal emission and reception. The satellite to station distance is deduced from this travel time.
Latitude, longitude & altitude measurements are taken from three satellites to provide coordinates of the GPS position. This is called the "pseudo-range" measurement. Satellites emit two types of pseudo-ranges: A precise code (P code),with a precision of around 10 meters, and a coarse code (C/A code), with a precision of around 100 meters. The precise code is encrypted and restricted to U.S. military receivers. Both provide incredible accuracy.
How to Choose the Best 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 is used to locate exact location and get you from Point A to Point B. There are lots of options rom hand-held units equipped with a digital compass to navigators that are installed in cars and commercial vehicles, and more. These are typically used as personal mapping systems and have limited recording/tracking capability.
Businesses are investing in mapping systems to increase productivity by improving route planning. Personal navigation devices, which can be used for geotagging, are also available.
The navigational system, often Bluetooth-enabled, provides several Points of Interest throughout your trip, as well as alternative routes to avoid traffic. GPS receivers to use with your PC, as well as software mapping systems that provide GPS mapping directly to your PC, are available from Deluo and Microsoft.
Used in the automotive industry, GPS Tracking records a log of all vehicle activity over an extended period of time. These devices are usually hidden under the dash and are useful in increasing productivity, and accountability, by maximizing business use of vehicles, and decreasing personal use. The best units provide instant tracking for position accuracy AND speed traveled, while built-in motion sensors only collect data during travel.
GPS Location provides Real-Time positioning and typically does not have tracking capabilities. GPS Location is mostly used for fleet vehicles and emergency location positioning. GPS Location includes a chart and involves "Pinging" the device via satellite or by cell phone, and returning its current position via satellite cellular technology. There is a recurring cost for GPS Location that does not usually apply to GPS Tracking.
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