by: Roger Mundy
Since the first GPS satellite was launched in February, 1978 from Vandenburg AFB in California, to the 12-channel parallel receivers found on most GPS receivers today, GPS has made significant strides.
Originally introduced as a military way of improving the accuracy of its weapon systems, and movement of its troops, GPS quickly found its way into the commercial market as both a business and consumer item.
Businesses used GPS with the Differential Global Positioning System (DGPS) as a means of measuring distances, and for tracking of vehicles. Companies like Magellan, Lowrance, and Garmin quickly entered the consumer market with crude 4-channel parallel receivers capable of picking up the satellite signals, but with a much greater margin of error then the military had.
The government imposed an intentional error system on the satellite signal to consumer GPS receivers called "Selective Availability" or SA, so that consumers would have nowhere near the accuracy the military had.
The reason for this was so that foreign governments not friendly towards the United States, and terrorists, would not be able to use the satellite signals for weapons aimed at targets in this country. In addition to the intentional degradation of the satellite signal the government imposed a measurement limit of 999 MPH and 60,000 foot altitude on consumer grade GPS units. Selective Availability was turned off in May of 2000 and has not been turned on again, but the altitude and speed limits still exist today.
Prior to the government turning off "SA", most GPS units could only provide an accuracy of somewhere between 100 and 300 feet of your actual position. When "SA" was turned off in May of 2000 the accuracy improved to 30 to 50 feet overnight! GPS enthusiasts were delighted at the improvement, but that was just the start of things to come.
Today there are more then 26 Satellites orbiting the earth some 12,000 miles up and beaming signals to GPS receivers all over the globe. The government is sending up more satellites with the relatively new system called "Wide Area Augmentation System", or WAAS, which when it is fully operational, will improve our accuracy to within 5 to 10 feet of our actual position.
Consumer grade GPS units now have 12 channel receivers capable of picking up 12 satellites at one time. New features such as Electronic Compasses, Barometric Altimeters, larger track logs, more memory for downloading maps, and units that are not only waterproof, but float, are making GPS units more desirable for the masses. GPS units with downloaded maps from a CD contain not only street level detailed maps of every road in every subdivision, but points of interest to direct you to the nearest hotel/motel, restaurant, shopping center, attraction, gas station, bank/ATM, hospital, police station, and much, much more.
Some hand held GPS units are equipped with "Automatic Routing" that will guide you from your current location to your destination with an automatic route and turn-by-turn voice guidance. No longer will the men of the world have to listen to that nagging question, "Why don't you stop and ask for directions!"
So where do you run out and purchase one of these remarkable GPS units? Well hold the phone! GPS units are as numerous as the different makes of cars, and with features equally abundant. So what is the best GPS unit to buy?
The answer is "It depends on what you are going to use the GPS unit for."
If you are going to use the GPS unit for traveling via car, motor home, SUV, or motorcycle then a mapping unit is what you are looking for. If you are going to use the GPS for hiking, backpacking, hunting, fishing, or mountain climbing, then a non-mapping unit will fill the bill. If however, you are going to use the GPS unit to travel the seven seas, then a marine unit is a must for you.
No matter which unit you choose you will have to choose between a myriad of "features." If all this sounds a bit confusing to you, and it should, then perhaps its time to learn a little bit more about the GPS world.
Many local community education departments put on a variety of classes for adult education. Check with your local community education department to find out if they offer GPS classes in your area.
Books are another way to learn about GPS, but with the way GPS is evolving most are obsolete before they are published. Yet another way to learn is via the internet. Garmin, Magellan, and Lowrance have websites that advertise their units, and there are numerous websites to help you learn more about GPS.
I would recommend a class if one is available, as it can teach you more than what GPS is all about. They may discuss different types of batteries for your GPS unit, whether or not you will need an external antenna, discuss screen size and resolution, and discuss the pros and cons of features found on GPS units.
Don't make the mistake of rushing out and purchasing a GPS unit without doing your homework first. I cannot tell you how many people I have known who bought the wrong GPS for what they intended to use it for.
Whichever method you use I hope you find the GPS unit that's right for you, and may it always get you home safely.
Got a new GPS unit for Christmas? Put it to use Geocaching. Learn How...
Geocaching is a high-tech Easter egg hunt played throughout the U.S. and even around the world by adventure seekers equipped with GPS devices. The basic idea is to locate hidden containers, called geocaches, outdoors and then share your experiences online. Geocaching is enjoyed by people from all age groups, with a strong sense of community and support for the environment.