How To Buy a GPS Unit
Because GPS (Global Position System) units are used in a wide range of industries many brands, models and
features are available. However, most units suitable for outdoor use are similar in size, cost, and complexity to a
cell phone. Here's some help to get you pointed in the right direction.
How GPS works
Global Position Systems units are a powerful technical tool in an easy-to-use interface.
- These units communicate with a network of satellites providing world-wide coverage.
- The satellites broadcast signals that your receiver uses to triangulate your position to within 100
feet.
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Types of GPS receiver units
Before you decide to buy a unit, consider what you want to do with it.
- Portable (hand-held)
- The compact and versatile design of these units allow them to be used for hiking, camping, hunting, and virtually any other activity that requires navigation assistance.
- Mounted
- Designed for use inside a vehicle.
- The larger size allows some of them to store more information (built-in maps) than hand-held
units.
- Chartplotter
- Designed for marine use to help you navigate bodies of water.
- Often include additional marine features such as water depth, water temperature and tide
prediction tables.
- Often used with fishfinders.
- GPS Software Systems
- Designed for use with portable computers or PDA's to turn the unit into a fully functional GPS.
- Requires a compatible operating system.
- GPS Fitness Systems
- Provides distance and rate of speed data to track your workouts
- Allows you easily navigate to desired locations
- Allows you to map your favorite routes
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Functions and features
-
Waypoints
- The eastern and northern coordinates that describe a particular position on the globe
- A waypoint can be a trailhead, campsite, rock formation, or a series of points on a featureless
landscape
-
Route mapping
- Creates a set of waypoints for an area you plan to visit
- Especially useful for trips to unfamiliar places
-
Routes
- An ordered series of waypoints. When following a route, the GPS selects each waypoint.
- Some units generate waypoints and automatically create a route as you travel, a handy feature if
you end up having to backtrack in bad weather or darkness
-
Altimeters
- Indicate altitude, or feet above sea level
- Very handy when hiking through mountainous terrain or when referring to a topological map
-
Antennae configuration / number of satellites
- External antennas can often be manipulated to improve reception
- Optional plug-in antennas are handy for use in cars or boats, since they allow the unit to pick
up signals in places (such as under a metal car roof) that satellite signals usually can't
penetrate
- Built-in antennas are protected from breakage, and can communicate with up to 12 satellites
- More satellites translate to more accurate positioning, faster updates and better reception
-
Connectivity
- A GPS unit can be made more useful via connections to a computer or another GPS unit. Most
computer and computer accessory retailers carry the cable and software you will need to take
advantage of these features.
- In addition to easy back-up, sorting, and additional mapping capabilities, connectivity allows
you to share exact information on where you're going or have been with someone else
- Size
- For backcountry use or when extra load weight is a concern, you may opt for a smaller, lighter
model
- If you will be using the unit in complicated outdoor terrain and/or urban locales, a larger unit
with a bigger screen may be preferable
- Battery life and extra weight are related. The more batteries a unit carries, the longer its
life and the heavier its weight. For long trips, the extra weight may be worth extended battery
life.
- Most GPS units are equipped with a lithium battery backup memory function so information won't be
lost when batteries die
- Weatherproofness
- While most receivers are built to withstand some exposure to rain and snow, they probably won't
fare well if submerged in a lake or river
- A beefier, and consequently heavier, casing means better weatherproofing
- A carrying case is a useful accessory, and can extend your unit's life span
- Screen size
- The display screen should be easy to read in a variety of light conditions
- Illuminated screens are especially useful for nighttime and low-light situations
- Color vs. black & white
- Usually based on personal preference.
- Color screens are often easier to read in nighttime and low-light conditions
- Memory
- In general, the more storage space, the larger the memory, the more room a unit has for
waypoints and route information
- Some units come with software to store waypoint data on your home computer, so you can collect
more information than the unit can hold on its own
- Some units offer an expandable memory
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