| Land surveyors once used tape measures and | | | | the fundamental elements of land surveying. The |
| transits to measure distances and positions. Since | | | | benefit of is that it is much more accurate than |
| the 1980s, electronic distance measurement, or | | | | hand-measuring these locations. There is some |
| EDM, devices have allowed for much more | | | | degree of error in all land surveying |
| efficient and accurate measurements. These use | | | | measurements, due to human errors, |
| a wave of energy that is shot between the EDM | | | | environmental characteristics like variations in |
| instrument and a reflector. The time the beam | | | | magnetic fields, temperature, and gravity, and |
| takes to return is then calculated as distance. | | | | instrument errors. GPS allows for much more |
| Today, such calculations can be done using | | | | precise measurements than previously available to |
| sophisticated GPS systems. | | | | land surveyors using measuring tape and an angle |
| The Global Positioning System uses a network of | | | | sight. |
| satellites to precisely pinpoint the device's location | | | | Another benefit of the use of its use as a land |
| on Earth at any moment. GPS uses the principle | | | | surveyor is that the coordinates can be located |
| of trilateration, using the location of several | | | | precisely, while other methods of land surveying |
| satellites to pinpoint an exact location. A receiver | | | | rely on measurements from other known |
| can determine the latitude, longitude, and elevation | | | | locations, such as the edge of the property line, |
| of a point using four or more satellites; there are | | | | the corner of a house, or another landmark. |
| a total of 24 Global Positioning System satellites | | | | These locations could change over time, such as if |
| currently in use. First created by the U.S. | | | | a house is torn down or another obstacle is built |
| Department of Defense as a navigational aid in | | | | between the structure and the measured point; |
| 1994, today it is used in many devices, tracking | | | | even a surveyor's stake may be removed before |
| everything from cell phones and delivery vehicles | | | | the land is re-surveyed. The coordinate of a given |
| to the movement of the tectonic plates of | | | | location on Earth, however, remains the same. |
| Earth's crust. | | | | Therefore, using GPS as a land surveyor |
| Land surveyors use Global Position Systems to | | | | produces measurements that will be accurate no |
| note the precise coordinates of spatial locations. | | | | matter what happens to the surrounding land. |
| Exact measurement of these positions is one of | | | | |