Handheld GPS use GPS Signal from a minimum of 3 overhead satellites to obtain a fix which is usually accurate to within 30m. Actual accuracy can be achieved down to 5m but due to US Military intervention accuracy is restricted. Handheld GPS can be carried by hand, and typically is battery powered. LCD display screens display the GPS navigation information.
The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). The GPS uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, that enable GPS receivers to determine their current location, the time, and their velocity (including direction). GPS was developed by the United States Department of Defense. Its official name is NAVSTAR-GPS. Although NAVSTAR-GPS is not an acronym, a few backronyms have been created for it. The GPS satellite constellation is managed by the United States Air Force 50th Space Wing.
