1. What is GPS?

2. How does GPS work?

3. What is WAAS?
    
4. Who uses GPS?
    
5. How do they use GPS?
    
6. What features should I look for in a GPS unit?
    
7. Where can I get more info?
    
8. Navigate our GPS selection

Where am I? Where am I going? And, how do I get there? Basic questions but darned good ones. Whether navigating uncharted waters, exploring new frontiers or one's own urban jungle, these are questions that have plagued mankind since creation. Maps, compasses and directions all have their drawbacks, as anyone who’s ever been lost, in spite of such navigational aids, can attest.

Enter GPS, the Global Positioning System, and the world of navigation has been forever changed.

What is GPS?

So, what is GPS, anyway? The Global Positioning System is a worldwide radio-navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. When first launched in 1973, the system was designed to provide the U.S. military a highly precise method of worldwide positioning. The Defense Department spent an enormous amount of money — about 12 billion bucks — on this super-sophisticated positioning system, which was originally intended solely for military use. But in the 1980s the U.S. government made the system available for civilian use.

Today GPS is available anywhere in the world, 24 hours a day, regardless of weather conditions, to anyone with a GPS receiver — a handheld, portable device that receives satellite signals and translates them into a wide range of user-friendly navigational information. There are no fees for its use (after all, our tax dollars paid for the system), and it's always up and running. With a GPS receiver you can determine your position or another position anyplace on earth within about 15 meters… and within about 3 meters with some of today’s latest receivers. Given that kind of accuracy, in combination with the highly sophisticated and readily available mapping software a GPS receiver can put to use, you can get directions to pretty much anywhere on earth. Not to mention turn-by-turn, street-level directions to anyplace in North America and many other countries throughout the world. Pretty cool, huh?

Imagine finding complete serenity at that remote camping spot your buddy recommended deep in Glacier National Park. Or getting back to the exact same fishing hole you happened upon two summers ago on your trip to Lake Tahoe. How about honing right in on one of the greatest snorkeling spots on earth, given only the GPS coordinates somewhere in the Bahamas? Or getting street-level, turn-by-turn navigational directions all the way from your home in Seattle to your friends' beach house in Sarasota, Florida — complete with indications of available lodging, restaurants, gas stations and attractions all along the way?

You could have all of that and more with a GPS receiver. Suppose now, that you're a rock climber or mountain climber. Since GPS renders your position in 3-dimensional space, it not only determines your latitude and longitude, but also your altitude. "Time to break out those O² canisters, boys." And, because it's synched to the atomic clocks onboard the GPS satellites, your GPS receiver also gives you one of the most accurate clocks on earth. But that's getting a little ahead of the story.

So, how exactly does GPS work?

Without getting too sophisticated, let's take a very basic overview. Remember those 24 satellites? Well, the Department of Defense not only launched them, but also maintains them along with launching replacement satellites as needed. And that's a good thing because the Defense Department operates those GPS satellites with the utmost precision. The 24 GPS satellites are placed strategically in space in very precise orbits in order to ensure that, at any given moment in time, at least 4 of them are "visible" to any GPS receiver anyplace on earth. Not at all coincidentally, simultaneous reception of 4 satellite signals is the same number needed for a multichannel, parallel GPS receiver (which would include almost any GPS unit sold today), to pinpoint your position.

These solar-powered satellites continually transmit radio waves detected by GPS receivers. The radio signals travel by line of sight, meaning that they will pass through clouds, glass and plastic but not through solid objects such as buildings, tunnels, caves and mountains. So you'll need a relatively unobstructed view of the sky to use a GPS receiver. GPS receivers do, however, work very well in other challenging environments such as dense urban areas or heavily wooded surroundings. That said, when you turn on your GPS receiver it will begin locking onto at least 4 GPS satellite signals simultaneously, interpreting their data in order to plot your position and any other positions you desire.

And there's a real plethora of data included within those GPS satellite transmissions — enough so, that your GPS receiver can tell exactly which satellites' signals it's receiving, where each of those satellites is positioned at that precise moment in time and how far away each one of them is from you. All of this information is gleaned based on the amount of time it takes your GPS unit to receive satellite signals. By simultaneously utilizing the data from each of the satellites to calculate your position (the technical term is triangulating), a GPS receiver is able to plot that position anywhere on earth to within about 15 meters. Pretty darned good, considering we're dealing with calculations based on satellites averaging 12,000 miles away and transmission velocities of 186,000 miles per second (the speed of light).

But, as we alluded earlier, it gets even better. While 15 meters accuracy is good, various U.S. industries and agencies, most notably the Federal Aviation Administration (FAA), wanted even better. After all, 15 meters isn't bad for finding a camping spot, but could leave something to be desired for an airplane pilot approaching a runway in near-zero visibility.

The WAAS System

So the FAA set about developing WAAS, the Wide Area Augmentation System. Basically, WAAS is a system of satellites and ground stations that calculate and transmit highly sophisticated GPS correctional data based on current conditions (compensating for things like partially blocked signals, "heavy" atmospheric conditions and so forth) in order to provide better accuracy. How much better? Try an average of 5 times better. So that means with a WAAS-enabled GPS receiver your average accuracy jumps from 15 meters to better than 3 meters 95 percent of the time, thanks to the WAAS correctional data it continually processes. What's more, you don't have to purchase additional receiving equipment (beyond your initial WAAS-enabled GPS receiver) or pay any service fees to utilize WAAS.

Who benefits from WAAS? Currently WAAS satellite coverage is available throughout North America. (So, although you can use a WAAS-enabled GPS receiver anywhere, if you are outside of North America you won't receive any of the WAAS correctional data). However, several other countries are currently in the process of constructing similar systems.

So that's the background of the Global Positioning System and the basics of how it works. But given this sophisticated technology, how can you put it to work… and to play? That's up next.

Outdoor adventurers of every kind use GPS

As you'll recall, we've already touched on some of the possible uses: pinpointing that special fishing hole, camping or snorkeling spot, to name a few. Or getting maps and directions to virtually anywhere in North America (and other countries) with GPS mapping software. And there's a whole lot more. In fact, GPS uses are almost as varied as the half million or more people who use them.

Some of the most popular outdoor adventure uses include: • Camping • Exploring • Traveling • Hiking • Hunting • Fishing • Boating • Mountain climbing • Sking • Automobile trips • Snowmobiling • Geocaching (treasure hunting).

How do they use their GPS receivers?

Navigation   Relocating a favorite hunting, camping or fishing spot   Aviation navigation   Nautical navigation   Automobile navigation   Wilderness navigation   Finding lost treasure, artifacts and archeological sites

Mapping Street-level mapping and directions   Mapping to tourist attractions, restaurants, fuel and lodging   Providing precise directional maps to uncharted areas   Providing precise directional mapping at sea   Mapping the most efficient plane, boat or vehicle route   Updating maps throughout the world

Positioning Locating a lost or injured camper, hiker, skier or climber   Determining the position of a boat or ship at sea   Determining the precise height or summit of a mountain peak   Determining the exact location of any spot you'd like to return to   Getting precise bearings, anyplace, anytime   Surveying for construction

Geocaching — the GPS tech sport

New and inventive ways to use GPS systems are being discovered all the time. Geocaching, for example, is the widely popular, relatively new high-tech sport of GPS treasure hunting. The basic idea is that individuals set up caches all over the world and share the coordinates of those caches on the Internet. GPS users then use those coordinates to find the cache. The cache is rated according to the type of terrain that needs to be crossed and how difficult it is to find.

Caches may contain small items such as local souvenirs, toy cars, trinkets, CDs — virtually anything that's non-perishable and small enough to fit in the cache container. Upon locating the cache, the rule is that if you take something from the cache you should leave something in return. And place your entry in the cache logbook after checking out the entries of all the other GPS'ers that have visited. Think of it as anything from a light hike to a full-fledged expedition (depending upon the cache location), but with the secondary purpose of making a cool discovery. Geocaching has caught on like wildfire and caches can now be found throughout the U.S. and 160 other countries.

As you can see, GPS has a multitude of fun and practical uses for everyone from outdoor and adventure enthusiasts, to travelers, campers, snowmobilers, skiers, mountain climbers, firefighters, rescue workers, surveyors, scientists, dispatchers, soldiers and many more.

GPS features to consider

Since there are no fees associated with GPS use, essentially the only things you need are a GPS receiver and batteries. There is, however, a wide range of GPS units available, with various features and options you may want to consider. Depending upon your personal needs, intended uses and budget, you'll have to decide which features suit you best. But, hey, that's when the fun part begins.

Garmin® GPS receiver features   Unit Type - GPS units may be expressly designed for particular applications such as automotive, general outdoor, aviation or marine use   Combination Units - 2-in-1 combo units (such as those shown at right and below, left), combine GPS receivers with a handheld PDA/GPS or a 2-way FRS/GMRS/GPS radio   WAAS-Enabled - Improves accuracy to about 3 meters 95 percent of the time   Touch-screen Navigation - simplifies navigation by putting it on-screen rather than accessing buttons   Voice Prompts - audible prompts provide turn-by-turn directions   Free Memory - the amount of free memory determines how much space you have for installation of optional mapping software   Basemap Units - receivers with built-in mapping software, such as U.S., North American or European highways, lakes, rivers, cities, airports   Mapping Units - receivers with ability to download detailed map data from CD-ROMs, providing greater street-level data, such as restaurants, banks, gas stations, marine navigational data, off-road trails and more

Waypoints - the ability to store a number of "waypoints" or given points along your route, somewhat analogous to bookmarking favorite Web sites on the Internet   Routes - the ability to store and recall entire routes you've chosen, including all of their waypoints and precise directions and reverse directions along those routes   Track Logs - the ability to generate a concurrent travel log as you go   Alarms - audible warnings for approach, arrival, off-course, waypoints, shallow or deep water   Screen - most GPS screens these days are easily readable high-contrast LCDs, color screens add vast detail   Trip Computer - additional calculators to display travel data such as odometer, current speed, average speed, trip timer and trip distance   Weather-Resistancy - after all, it's an outdoor device: a waterproof or water-resistant housing is an important consideration   Buoyancy - some GPS units will float, a potentially important consideration for boating, rafting or fishing   Dashboard Mount - an important consideration for automotive or marine use