- GPS, which stands for global positioning system, relies on the Global Navigation Satellite System. This network of 32 medium Earth-orbit satellites can send microwave signals to any Earth-based GPS receiver. These satellites can determine the location, time and velocity of each GPS receiver. Many hand-held GPS devices are also capable of giving driving directions.
- Companies like Magellan Navigation, Trimble Navigation and Garmin offer hand-held GPS devices ranging from $100 to $900. Most hand-held devices use display screens and are equipped with up to 20 channels, with each channel being able to link with a different satellite. Expensive models often come with color screens, NMEA 0183 outputs, temperature and barometric pressure monitors and chart plotters. Magellan and Trimble make hand-held devices that are great for surveying and navigating. Garmin features GPS navigation software for laptop PCs and pocket-size GPS receivers that include Bluetooth FM transmitters.
- The U.S. military issues hand-held GPS devices to many of its commanders and soldiers. Both the Commanders Digital Assistant and the Soldier Digital Assistant can aid in finding targets in otherwise unknown territories. Commanders often use GPS to organize troop and supply movements. These hand-held devices are also used to find military personnel who are unaccounted for and unresponsive.
- The benefits of having a hand-held GPS receiver are numerous. Sailors, pilots, mountain climbers, fishermen and hunters use these devices to keep track of their exact locations and avoid areas that may be dangerous. Truck drivers and delivery companies have reported an increase in productivity after instituting the use of hand-held GPS devices. Additionally, the convenience factor of never being lost is enough for many individuals to purchase these devices.
- GPS receivers can experience natural interference. Electromagnetic radiation in the atmosphere can desensitize GPS receiver signals. Solar flares can cause GPS interference across large portions of the planet. The north and south poles often experience major geomagnetic storms, which can cause problems with satellite signals. Moreover, if a satellite fails, a GPS device may be useless for a matter of days.
