Why are GPS units showing up everywhere? You might find one in your rental car, on your wristwatch or even built into your wireless phone. Anti-theft systems use one, heavy construction equipment might use one and having one on your boat now seems to be a requirement. Anytime we want to know our exact location on the face of the Earth, the GPS becomes indispensable. Like many other technologies, feature rich GPS units are now affordable for the average person. So how do you know which one to purchase? Let’s look at few things to consider prior to buying your next GPS unit, but first, what is a GPS unit?

A GPS (Global Positioning System) unit has the primary function of calculating its own location on land or water by using satellite signals. Once the GPS unit knows its own location, it can help the user determine direction and distance to other known locations. For instance, a GPS on a boat can tell the captain how far it is to the shoreline or how far it is to a favorite fishing spot. For the outdoor sportsman a GPS can help with finding your campsite, your vehicle or your next geocache. Popular outdoor activities such as hiking, hunting, fishing, trail running, backpacking, rock climbing, canyoneering and canoeing are all made more enjoyable and safer when you take along your GPS.

When buying a GPS system the first thing to consider is how you intend to use it. If you plan on using it while on foot, you’ll want a GPS that is lightweight, compact, weather resistant and that is equipped with features important to foot travel. WAAS (Wide Area Augmentation System) is one such feature. WAAS greatly increases the accuracy of your GPS, in most cases to within 10 feet. Accuracy within a few meters is important for the outdoor enthusiast but not nearly as important for navigating through town in your rental car. Next, be sure your GPS has at least 12 channels of reception too. Since your GPS will only work when it receives signals from satellites orbiting the Earth, less than 12 receiving channels will not get the job done in wooded areas or in steep terrain. If you plan on using your GPS to navigate while driving in your car, its weight is not nearly as important as its ability to display street maps. The GPS mounted to the dash of your truck probably doesn’t need to be weatherproof, but the one on your boat better be.

Here are the features and products I recommend. For the outdoor athlete or sportsman, be sure your GPS has these features: topographical mapping, back tracking, a computer interface, weatherproofing, 12 receiver channels and WAAS. I recommend portable GPS units in the Garmin eTrex Series and the Magellan Meridian Series. For driving applications, be sure your GPS has these features: street mapping, large display, a computer interface and external antenna compatibility. I recommend automotive GPS units in the Garmin StreetPilot Series and the Magellan RoadMate Series. For boating and other marine applications, be sure your GPS has these features: marine mapping, color screen, active sonar, back tracking, a computer interface and weatherproofing. I recommend marine GPS Units in the Garmin GPSMAP Series.

Prices for GPS units vary a great deal and in general, you get what you pay for. While some units cost around $100 and offer relatively few features, others may cost as much as $1000 or even more and are loaded with dozens of features. Here is a good rule of thumb for determining how much money to spend on your next GPS. You should expect to pay between $200 and $300 to get a decent GPS Unit. I own a Garmin eTrex Vista. I believe it is the best GPS available for under $300.

If you don’t have a GPS or yours is more than five years old, now’s the time to get one. Adding a new GPS to your inventory of backcountry toys will take your outdoor adventures to a new level of enjoyment. Use this information and you’ll Get It Right The First Time. Get Outdoors!

Chuck Fitzgerald is the owner of Arizona based BackCountry Toys, an online specialty store with the “Best Gear Out There” and dedicated to helping outdoor enthusiasts to “Get It Right The First Time” with timely educational information. Please visit http://www.BackCountryToys.com to find great gear and to receive the Fact & Tips e-newsletter, “FreshAir”; (800) 316-9055.

I took a look at some of the online offers for free GPS software and found, like many “free” offers there were often limits and provisos involved. Often the freeware is a scaled–down version of purchasable products. Sometimes the free product has restricted functionality with features disabled, other products are trial–based and are disabled after a certain time (hours or days or use).

An example of limited free GPS software can be found at GPS Utility. The downloadable freeware is limited 100 waypoints and 500 track points. (There are 65,000 of each in the registered version of their program.) The free program gives you a good opportunity to try before you buy, and this is the benefit of most free programs.

There are online sites that list various free GPS software and describe how to use the programs after you download them. Often individuals who have used the programs themselves develop the sites. These are great because they give you an unbiased interpretation of the benefits and disadvantages of the programs before you use them.

Using free GPS software you can download programs that allow you to retrieve and display aerial photos, topographical maps, USGS landmarks. There are programs available that allow you import scanned images and add latitude and longitude points and other data.

Free GPS software downloads are available for PDA units that are capable of communication with GPS receivers. With these downloads you can have a useful navigation assistant, location database manager, and GPS data converter.

Programs to manage GPS waypoint and route files are available for both PC and Mac users. The waypoints and route files can be saved or converted to various formats used by other mapping programs.

If you need to transfer information to and from your GPS receiver and your home computer or laptop there are several free programs that allow you to do so. There are also programs that allow Garmin GPS receivers to “talk” to one another.

Many of the programs listed here are directed at the hiking/trekker community, but there are also free programs available for auto GPS systems and marine navigational systems. I found a couple of marine navigation programs that allow you to download nautical charts and plotters.

There are free GPS software programs that allow you to download street maps that might not be included in your auto–navigation system. If you intend downloading in–vehicle software, make sure that it has audio capacity, an essential safety factor for motorists. One such program offers data for several countries with voice guidance in twelve languages.

Free GPS software is also available for downloading to your cell phone. This is mostly tracking software and can be phone specific. You might want to check with your carrier before downloading anything to your cell phone to make sure that it does not incur extra charges.

As satellites are constantly moving, it is helpful to know the optimal time for data collection in your area. There is free GPS software that includes an almanac to let you know the availability of satellites at any given time.

Some of the free GPS software is brand specific. Programs designed for a Garmin receiver may not work for a Magellan, so check out the specifications carefully, especially if you intend purchasing a registered version after your trial period. Other software works with most brands.

Anne King is a sports and recreation writer in Boise, Idaho. For a list of free GPS software, visit Maps GPS Info.com which also provides practical information on GPS and maps that everyone can use. The website includes product reviews and a maps/GPS glossary.

Global Positioning System (GPS) is a navigational aid originally developed for the military. The system simply receives signals. It is the applied technology that gives the GPS its versatility.

If you have ever used map and compass, you will understand a little about how the GPS works. In order to find your position on a map, you need to have three points of reference. The intersecting line from the reference points is where you are. Map and compass work uses triangulation (bearings), GPS uses trilateration (distances) to calculate location. Satellites orbiting the earth emit unique signals that can be received by a GPS. The GPS software interprets the signal, identifying the satellite that it came from, where it was located, and the time that it took for the signal to reach the system. Once the receiver has both time and distance it begins to determine position.

Three satellites provide the intersection point and the fourth is used to check that the positioning is accurate. Accuracy depends upon the synchronization of atomic clocks in the satellites with the clock in the GPS system. Although the clock in the GPS is not
atomic, utilizing the fourth satellite gives it that functionality as the internal clock adjusts itself to correct any discrepancy discovered.

GPS has gone far beyond its initial military application. Drivers can find their way through city streets, long distance trekkers use the technology to cross unfamiliar terrain, mariners and pilots use GPS enhanced data to cross the seas and skies.

In–vehicle GPS can be integrated into the car entertainment system or can be installed as a removable device. These systems need to tell the driver where he/she is and how to reach their destination. The information includes road directions plus relevant features along the way such as rest stops, gas stations, points of interest, etc. Auto GPS uses voice commands so that the driver can concentrate on the road.

Hikers and trekkers use similar technology, but normally without the inclusion of road systems on their devices. Mapping software defines the territory that the hiker will encounter. The user can enter waypoints (points of reference) so they can return using the same route. They can add points of interest such as water sources, possible campsites, and other items of interest on their trail. However, the portability demanded by hikers will also limit the functionality of the system as small screens mean that some detail will be lost.

It is GPS technology that is used to track individuals on home arrest, to trace missing pets, stolen vehicles, and missing people. Small systems can be incorporated into pet collars and wristwatches. As long as the receiver is active, it can be found.

Marine and aviation GPS units are sophisticated and specialized. The principles involved are the same as any standard system; the software is much more highly developed.

Any fisherman, who is using a fish finder on his boat, is using a GPS that is enhanced by sonar and tracking devices. Units have been developed for use on float tubes also — as GPS technology advances, the systems become more and more compact and their uses
more and more extensive.

If you are considering purchasing a GPS, make sure that it can be updated easily. This is especially true if you buy a multi–function GPS or one that is used where conditions change regularly. An in–vehicle GPS soon loses its usefulness if it is not updated as road systems change.

Updates vary according to the device being used. They can come in CD/DVD packages or as computer downloads. The user can purchase maps specific to the area in which the GPS will be used or a range of maps and routes. These are available from GPS software
companies who will charge proportionally to the sophistication of the software.

GPS units vary in price according to their usefulness. It is possible to buy units for less than one hundred dollars to units costing more than one thousand dollars. What your needs are
will be a factor in the cost of your unit. If you are a backpacker then portability is a major consideration. If you are a trucker, you need to be able to find a delivery point as quickly and conveniently as possible. Whatever device you go for, cost is generally related to quality. Buy the best you can afford.

Anne King is a sports and recreation writer in Boise, Idaho. For more GPS information, visit Maps GPS Info.com which provides practical information on GPS and maps that everyone can use. The website includes product reviews and a maps/GPS glossary.