GPS Navigation Devices

Only a few decades ago, it would have sounded like a science-fiction plot. We're going to put an array of machines up in space orbiting the Earth, and use them to navigate the globe. Only hard SF authors like Isaac Asimov and Larry Niven thought that big.

But today, the Global Positioning System (GPS) is a reality, and a working one at that. As of the year 2008, there are 31 active satellites in the GPS constellation, with a 32nd being introduced as soon as they work the bugs out of it. Introduced by the United States Department of Defense, its name is NAVSTAR-GPS, and it's managed by the United States Air Force. The US government mandated that the system be made available for public use in 1983.

Other upcoming satellite navigation systems currently in the works include Russia's GLONASS, which would have been completed sooner had the former Soviet Union not been so... well... former, the European Union's Galileo system, be operational by 2013, China's proposed Compass system, which is to include 35 satellites, and India's "Indian Regional Navigational Satellite System" (IRNSS), scheduled to be launched in 2009 and completed by 2012.

With all this flying space junk up there, you should have no problem finding a signal! GPS systems are definitely here to stay. While these systems were originally deployed for military and commercial shipping and flying use, they've since become the standard for end user consumers to use for navigation as well, even to the point of trivial recreational use, such as with geocaching.

The way that GPS systems can be used for navigation is by triangulating on a signal from space and using the time it takes to receive the signal to determine the distance from the source of that signal. A signal from one satellite isn't very helpful - that could be an infinite number of points around a circle on the face of a globe. The signal from two satellites is somewhat useful, since there's only two points on the surface of a globe which can match the distance from two satellites.

With the exact distance from three visible satellites, you have a theoretically perfect pinpoint location, but such accuracy would require a highly accurate clock - we're talking nanosecond accurate. Thus, four or more satellites are used and the results can be easily averaged out to indicate the location of the received signals. That should help explain why we have so many redundant satellites up there, and remember also that you can't receive a signal which has to be traveling straight through the Earth.

The most typical use of a GPS receiver for private use is automotive navigation systems. These devices interpret the data from satellites and download maps from Internet servers or use built-in mapping software to display the current location of the device, and can easily be clipped to the visor of a car and used like a live, updated map.

Another use is personal hand-held devices for various kinds of outdoor work and recreation. These applications include hiking and camping activities, but can also help dispatch fire fighters in a forest setting or assist with wilderness search and rescue. They can range anywhere from devices which track a signal from a simple wristwatch to hand-held devices which display a graphical map, either of streets and cities or terrain.

Companies which rely on a mobile dispatch model are also increasingly turning to GPS systems for tracking their units. Companies such as mobile repair services and taxicab services use the devices both to dispatch the nearest unit and assist individual drivers with navigation. Police, fire, and paramedic units are dispatched in cities with the assistance of GPS. GPS tracking is even coming into use in package delivery - you just might be able to pinpoint the exact location of your package in the very near future when it's being handled by UPS or FedEx.

A typical GPS system is made up of GPS terminals, some form of mapping data service, and service centers. These systems typically tie together diverse technologies of Internet, mobile terminals and networks, and automotive and consumer electronics such as mobile phones. The market is rapidly developing, and each company has to keep coming up with new innovations and ways of providing their products cheaper in order to stay competitive.

Filed Under: Mobile Computing