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What is GPS?
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How does GPS work?
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What is WAAS?
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Who uses GPS?
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How do they use GPS?
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What features should I look for in a GPS unit?
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Where can I get more info?
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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?
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Navigation
- Relocating a favorite hunting, camping or
fishing spot
- Aviation navigation
- Nautical navigation
- Automobile navigation
- Wilderness navigation
- Finding lost treasure, artifacts and
archeological sites
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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
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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
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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.
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- 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
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