Answer: The Global Positioning System (GPS) is a surveying method used to precisely locate a three-dimensional position (latitude, longitude, and elevation) anywhere on the surface of the Earth. The system can be used at any time under all weather conditions.
Explanation: The Global Positioning System (GPS) is a surveying method used to precisely locate a three-dimensional position (latitude, longitude, and elevation) anywhere on the surface of the Earth. The system can be used at any time under all weather conditions. The GPS has replaced traditional survey methods as a low-cost, high-accuracy technology. It is also a very quick survey method to use, which on hazardous waste sites, serves to minimize personnel exposures to a variety of potential hazards.
GPS is based on a constellation of 24 non-geosynchronous satellites orbiting 21,000 kilometers above the Earth. The GPS satellites transmit coded radio frequency signals which are used to accurately determine the position of ground-based receivers. The range or distance to the satellites is determined by measuring the time the signal is sent from the satellite minus the time it arrives at the receiver, multiplied by the speed of light. By simultaneously measuring the distance to four satellites, one receiving position can be determined to an accuracy of 30 to 50 meters. If more than one receiver is used, the coordinates of a roving receiver can be determined relative to the other, fixed receiver to within an accuracy of a few meters to a few millimeters, depending on the type of receivers used, distance between the receivers, and the accuracy to which the satellite positions are known. High-precision GPS receivers, along with precise satellite orbits, can be used for high accuracy applications, while hand-held systems can be used for environmental mapping, for gathering data for geographic information systems, and for resource inventories.
