The GPS or Global Positioning System is a "constellation" of 24 well-spaced satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. The location accuracy is anywhere from 100 to 10 meters for most equipment. Accuracy can be pinpointed to within one (1) meter with special military-approved equipment. GPS equipment is widely used in science and has now become sufficiently low-cost so that almost anyone can own a GPS receiver.

The GPS is being used in science to provide data that has never been available before in the quantity and degree of accuracy that the GPS makes possible. Scientists are using the GPS to measure the movement of the arctic ice sheets, the Earth's tectonic plates, and volcanic activity.

GPS are much more applicable when they are eminently portable. Usually, when people refer to portable GPS units, they mean handheld units. Types of GPS devices such as these are most often for biking, hiking, camping, sailing, fishing, skiing and exploring in the untamed wilderness.

Portable Global positioning systems and accessories come in the forms of hand held units, antennas, wristwatches, bike mounts, fish finders, and more. Since nearly major GPS manufacturer makes portable units, a lot of people are demanding for serious, strong GPS units.

Portable GPS systems give user such data as longitude, latitude, altitude, speed, and distance to destination or next stopping point. Stopping points are called "waypoints," and they can be programmed into the GPS unit, as can a number of other points. There are a number of styles of portable GPS systems, so that everyone can find the model and the price that is just right for them.

Magellan, Garmin and Lowrance are among the top-quality major brands portable GPS systems. GPS systems are surprisingly affordable for the people who are looking into GPS technology for the first time. Even the most basic GPS unit offers a wealth of data to the user.

GPS units like maps are usually less comprehensive than those used for driving and boating. Topographical maps are the most useful maps for use in the wilderness which allow you to locate yourself within your immediate surroundings and navigate over rough terrain. However, not every unit comes with topographical maps. So if you want them, just make sure you buy a unit that includes them.

Wilderness GPS units are example of portable GPS units which is more or less accurate depending on their design and construction. Units that utilize differential GPS are far more accurate than those using standard GPS standard protocols. Also, units that use dual frequencies and kinematic (On-The-Fly), real-time, signal processing are more accurate than those using a single frequency and static, post-processing.

There are optional features in Wilderness GPS DEVICES that are less necessary for other applications but extraordinarily helpful for wilderness applications are included compasses, barometers, and altimeters. Some portable units can even receive weather forecasts so you will never be caught off guard by a sudden storm.

Furthermore, it is a device's ability to communicate with other receivers in the area to send emergency voice communications and the ability to communicate with other receivers in the area to send emergency voice communications and the ability to broadcast an emergency beacon should you find yourself cut off and distress.