Global Positioning Systems Buying Guide

Buyers' Guide to Global Positioning Systems Contents

• What is a GPS unit and why do you need one?
• Big brother is watching
• Fun and GPS games
• What to look for in a GPS
• How the GPS works
• More than one system
• Location, location

-------------------------------------------------------------------------------------------------------

Next time someone tells you to "Get lost!" - just smile and tell them calmly that you can't, thanks to your pocket GPS navigation unit. Be sure to watch their face.

Okay, that is probably not the best reason to shell out a couple of hundred dollars or more for a GPS (Global Positioning System) unit, but there are, in fact, plenty of good reasons to do so - not the least of which is the joy of never again having to interpret an upside-down street directory.

What is a GPS unit and why do you need one?

The GPS (Global Positioning System) is a "constellation" of 24 satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location by a system of triangulation. It also gives you a highly accurate time reference thanks to the atomic clock on board each satellite. The GPS system was built and controlled by the United States Department of Defense, but it can be used by anyone with a GPS receiver unit, free of charge. Most general-use GPS receivers can locate a user with an accuracy of better than 10m.

Following the launch of the first satellite in 1978, GPS equipment was largely used in military and scientific applications. The primary military purpose of the GPS is to be able to tell exactly where the troops are, and for accurate targeting of smart bombs, cruise missiles, or other weapons. The satellites also carry nuclear detonation detectors -- a major part of the United States Nuclear Detonation Detection System.

Scientists, on the other hand, rely on GPS systems to provide accurate data that was never available previously. This has enormous benefits in geological studies such as measuring the movement of the Earth's tectonic plates (seismology) and arctic ice floes, along with volcanic activity.

Outside the scientific arena, everyday commercial applications for GPS receivers are expanding. The system is used as a navigation aid in aeroplanes and ships, plus computer-controlled machinery such as harvesters, mine trucks and other vehicles. In recent years, GPS technology has entered the consumer market, with lower costs enabling everything from boat- and car-based systems, down to pocket-sized personal models (an essential item for would-be woodsmen). GPS units can also be bundled into PDAs (Personal Digital Assistants) and personal GPS units are almost de rigueur for any serious outdoor adventuring, such as bushwalking, cross-country skiing, ballooning, sailing, and flying.

They are also becoming standard equipment on many cars, trucks and commercial vehicles. In these conveyances, the features go far beyond replacing the ever-handy street directory. Today's GPS receivers can not only tell you where you are and direct you (often vocally) where to go, they can also display a range of valuable information like traffic and weather details. Add on information packs can even tell you the location of traffic "black spots", fixed speed cameras and red light cameras. And avoiding one of those even once can just about pay for the system!

Big brother is watching

GPS is all about being able to tell where things (or people) are. So it is no surprise that many commercial applications have developed for vehicle monitoring. Some companies are now using GPS systems to monitor their vehicle fleets, giving them detailed reports on where their vehicles are and for how long. This application, however, is starting to get into the realm of "big brother" (no, not the reality TV show - the Orwellian idea of constant monitoring of individuals for control purposes).

Using this system you could monitor the vehicle of a sales rep, for instance, and tell when and where he was at all times; when the car was stopped, idling or mobile; if it strayed out of his "territory" and even if he made an unauthorised stop at McDonalds!

While sales reps may not applaud the idea of such close surveillance, a GPS unit in a luxury car is becoming a must-have feature - not only to assist drivers to find their way around, but also to help prevent theft and assist in vehicle recovery. An anti-theft GPS unit can tell if a car is operated by an unauthorised user (GPS-speak for "stolen"). The unit emits a "vehicle tamper" notification which is received at a central monitoring base and police or private response teams are able to track the vehicle. Some can then immobilise the vehicle at the discretion of the pursuers. This type of system can even incorporate a "panic button" which can be used in the event of car-jacking; and incorporate an anti-tow sensor, so the vehicle can't even be picked up and carried away.

GPS tracking is can also be applied to people. In other "big brother" news, it was reported recently in New Scientist that kids in Japan will soon be wearing GPS transceivers in their school blazers, allowing parents to track their whereabouts on a laptop!

Meanwhile, wearable GPS bracelets and anklets have been developed for tracking prisoners on probation or under house arrest. A similar device was reportedly pilfered by a burglar, who didn't know what it was but thought the techno-looking device must be valuable. Police wasted no time in tracking the device and educating the unwary thief.

Fun and GPS games

Like to travel? Fancy a bit of sleuthing? With a personal GPS receiver you can do both. The popularity of personal GPS units has even resulted in a new "sport" called Geocaching. Sort of like a high-tech treasure hunt, Geocaching involves using a GPS receiver to find a "geocache" (or "cache") placed in a specific (and sometimes difficult) location, the co-ordinates of which are posted on the Internet. A cache is typically a small, waterproof container containing a logbook and a "treasure". Don't get too excited yet - the "treasure" is usually not valuable at all, but finders still get a thrill from getting to it first. Geocaching is spreading worldwide. For more info, check out Web sites like: www.Geocaching.com, www.Terracaching.com and www.Navicache.com

What to look for in a GPS

Assuming that you are looking for a GPS unit for personal use, it will likely be either an in-car system or a personal device. You may travel a lot and/or have a bad sense of direction, or you might just want to take advantage of the growing range of practical applications for this handy technology. In any case, here's a few things to bear in mind when shopping around.

To help determine what sort of unit you need, consider the following: Do you regularly reach for the street directory or travel to unfamiliar areas? You are a prime candidate for a GPS unit.

Your department store source to buy cheap used and new items online