Today's GPS receivers are extremely accurate, thanks to parallel multi-channel design. Garmin 's 12-channel receivers is quickly switched on the satellite at the first barrier, and they have a strong locks, even in dense foliage or urban environments with tall buildings. Certain atmospheric factors and other sources of error can increase the accuracy of the GPS receiver. Garmin ® GPS receivers are accurate to 10-15 meters on average.
Newer Garmin GPS receiversWAAS (Wide Area Augmentation System) capability can improve accuracy to less than three meters on average. No additional equipment or fees are necessary to the advantage of WAAS. Users can also better accuracy with Differential GPS (DGPS), which corrects GPS signals within an average of three to five meters. The U.S. Coast Guard operates the most common DGPS correction service. This system consists of a network of towers that receive GPS signals and transmit a correctedBeacon signal transmitter. To get the corrected signal, users must be a differential beacon receiver and beacon antenna in addition to their GPS.

The 18-24 satellites that make up the GPS space segment are orbiting the earth about 12,000 miles above us. They are constantly moving, making two complete orbits in less than 24 hours. These satellites are at speeds of around 7500 miles per hour.

GPS satellites are operated by solar energy. They have backupBatteries keep on board, operating in the event of a solar eclipse, when there is no solar power. Small rocket boosters on each satellite keep flying right into the path.

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