GPS Coordinate Data - How Does It Pinpoint Your Exact Location? |
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By: Alan Granger Posted: 2006-11-02 01:56:29 |
| Like many people, you may be wondering how GPS coordinate map readings are used by your GPS vehicle tracking system to pinpoint your vehicle's exact location at any given time.The simplest way to represent a point on a two-dimensional map is by using two lines that cross. One line goes up and down while another goes from side to side. Where they converge is the point you're interested in. It could be a campsite or lake or waterfall, or wherever you're standing at any given point in time - or - the location of your car.A GPS coordinate system expresses all locations on earth using two of three coordinates found in a spherical coordinate system that's aligned with the spin axis of the earth.GPS coordinates are returned as a pair of number sets - one set of numbers for the first line and a second set for the other line. These lines are known by people who work with maps as global positioning system coordinate lines. The place on the map where the two lines meet represents your location point.Different GPS coordinate systems have been developed to pinpoint map locations on the spherical planet Earth. The most popular seems to be the positioning system that shows standard degrees-minutes-seconds coordinates.There are a total of 360 degrees but you can only go as far as 90 degrees north or south latitude. You can only reach just shy of the 180-degree mark east or west longitude. At the area of the equator, longitude degree stretches to over 69 miles wide, necessitating smaller divisions for accurate depiction of points.It can help to think of this GPS coordinate system as a clock - think of each degree as equivalent to one hour. One degree is broken up into 60 minutes, and one minute into 60 seconds. One minute is still over one mile wide at the equator. A second, at 0.0192 miles is a bit more manageable, but still more than 100 feet.The longitude lines draw closer together till they reach the poles. Latitude lines, on the other hand, remain at the same distance from each other all the way to the poles. Distances between latitude lines are easier to figure out as they're always the same figures given for the equator longitude numbers. To maintain accuracy, a degree=69.1722 miles, a minute=1.1528 miles and a second=101.45 feet.Another system is the decimal format. This system is commonly used by GPS vehicle tracking system manufacturers for handling data within their GPS units. When a user selects a different GPS coordinates format, the data gets converted from decimal to the requested format, and displayed on the GPS unit's screen. In this system, the seconds appear absent. (They are there, only they're indicated as decimal fractions of minutes.) |
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