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A Comprehensive Guide to GPS Products

When selecting a GPS unit, you must consider the features most important to your needs and budget.

Whether built into your smartphone or a stand-alone device, GPS devices make it nearly impossible to get lost. Many GPS units include detailed maps for driving or hiking, and some have geocaching features. High-performance models feature barometers or electronic compasses, internal memory, more maps, and advanced navigation features. Consider how these options fit your needs before choosing your next GPS device.

How GPS Works

Today, like the Garmin brand, GPS technology is used by doctors, scientists, farmers, truck drivers, athletes, soldiers, hikers, boaters, and hunters. It is also widely available in digitally connected smart devices like phones, wearable tech, and even cars and bikes, allowing owners to keep tabs on their products and know where they are at all times. The system uses a constellation of satellites to provide precise positioning information. These satellites are powered by rubidium clocks that broadcast highly accurate timed signals that GPS receivers can pick up on land, sea, and air.

Once the GPS receiver’s antenna can see at least three of the four satellites, it can calculate its position. This process, known as a lock or fix, can be delayed by atmospheric effects such as ionospheric delays or heavy cloud cover. Software-based errors and intentional interference, such as jamming or spoofing, can also impact GPS accuracy.

The GPS technology employed by the US Department of Defense (NDOD) was first developed in 1993. Still, other countries have since launched their satellite systems to create Global Navigation Satellite Systems (GNSS). Each design is different, but all use the same basic principles to determine an individual’s location by measuring their distance from a set of satellites. Our Introduction to GNSS on-demand webinar series goes into these differences in more detail.


A GPS waypoint is a point that marks your current location on a map and can be used to create a route. Generally, they are identified by coordinates in the form of degrees of longitude and latitude — lines that run north-south on the globe. For example, a waypoint could be the location of a pond or the halfway point between two points on an en-route chart.

Aside from being the building blocks of navigation, waypoints have other uses in life on Earth: Wildlife biologists use them to track animal migration, and engineers use them when designing buildings or parks. You can use your GPS to save any coordinate as a waypoint, then navigate directly to that spot.

GPS receivers often identify and save multiple waypoints to create routes that can be followed for various purposes. For example, the route from camp to the top of the mountain will involve several waypoints, such as the trailhead and the campsite.

Drones also make use of waypoints, especially for teleoperation and autonomous flight. Waypoints enable drones’ “go-to” function, which lets you select a specific destination. From there, the drone automatically flies to that location. It will be programmed to avoid obstacles, such as trees or rocks.


Whether on paper or on a GPS device, maps are sets of visual directions that describe nearly anything about the world. They may have symbols for rivers, lakes, cities, capitols, different kinds of roads such as highways and side streets, or even the types of environments in a particular area, like deserts or marshlands. Most maps also contain a key or legend to decipher these symbols. Maps are often griddle, with latitude and longitude lines labeled alphabetically in one direction and numerically in the other.

Most GPS devices come with rudimentary basic maps that distinguish roads from other features, but topo maps can be purchased separately or downloaded for free from many websites. Some GPS manufacturers offer software to organize and display the waypoints and tracks you create on your device.

NSSP holds introductory classes on GPS use and is happy to give one-on-one tutorials to stewards who need them. For more information about classes, visit our Safety and Technology page. The NSSP also offers training for volunteer-based monitoring projects, such as our forestland survey.


The Global Positioning System (GPS) network consists of satellites in orbit above Earth that beam down signals to users on the ground, including geographical data points and time codes. These data points allow GPS device holders to pinpoint their location, determine the speed and direction of travel, and calculate how long it will take them to get from one point to another — an exercise known as trilateration.

Once a technology born of military necessity during the height of the Cold War, GPS is now used by many different industries. For example, GPS is incorporated into fleet vehicle tracking devices to help improve business performance by increasing driver safety, efficiency, and profitability. It is also a valuable tool for hiking or trekking enthusiasts to chart their course and navigate uncharted territories. The police and emergency services even use it during search-and-rescue operations at sea or in inclement weather.

When selecting a GPS unit, you must consider the features most important to your needs and budget. For instance, how many waypoints and tracks can the device store? Does the unit have an electronic compass for real-time navigation or to help determine cardinal directions when not moving? Other important considerations are display and memory. Some units offer more robust features, such as cameras and ruggedness, while others are more affordable and simpler in design.



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