Editing Surveying (section)

===20th century===
[[File:William Francis Ganong surveying Chiefs Mountain.jpg|thumb|[[William Francis Ganong]] surveying in 1903]]
At the beginning of the century, surveyors had improved the older chains and ropes, but they still faced the problem of accurate measurement of long distances. [[Trevor Wadley|Trevor Lloyd Wadley]] developed the [[Tellurometer]] during the 1950s. It measures long distances using two microwave transmitter/receivers.<ref>{{cite web|last1=Sturman|first1=Brian|last2=Wright|first2=Alan|title=The History of the Tellurometer|url=http://www.fig.net/pub/fig2008/papers/hs01/hs01_03_sturman_wright_2833.pdf|publisher=International Federation of Surveyors|access-date=20 July 2014}}</ref>
During the late 1950s [[Geodimeter]] introduced [[electronic distance measurement]] (EDM) equipment.<ref>{{cite web|last1=Cheves |first1=Marc |title=Geodimeter-The First Name in EDM |url=http://www.profsurv.com/magazine/article.aspx?i=394 |access-date=20 July 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140310225310/http://www.profsurv.com/magazine/article.aspx?i=394 |archive-date=10 March 2014 }}</ref> EDM units use a multi frequency phase shift of light waves to find a distance.<ref>{{cite web|last1=Mahun|first1=Jerry|title=Electronic Distance Measurement|url=http://jerrymahun.com/library/Distance/a.htm|website=Jerrymahun.com|access-date=20 July 2014|url-status=dead|archive-url=https://web.archive.org/web/20140729013241/http://jerrymahun.com/library/Distance/a.htm|archive-date=29 July 2014}}</ref> These instruments eliminated the need for days or weeks of chain measurement by measuring between points kilometers apart in one go.

Advances in electronics allowed miniaturization of EDM. In the 1970s the first instruments combining angle and distance measurement appeared, becoming known as [[total station]]s. Manufacturers added more equipment by degrees, bringing improvements in accuracy and speed of measurement. Major advances include tilt compensators, data recorders and on-board calculation programs.

The first satellite positioning system was the [[US Navy]] [[Transit (satellite)|TRANSIT system]]. The first successful launch took place in 1960. The system's main purpose was to provide position information to [[Polaris missile]] submarines. Surveyors found they could use field receivers to determine the location of a point. Sparse satellite cover and large equipment made observations laborious and inaccurate. The main use was establishing benchmarks in remote locations.

The US Air Force launched the first prototype satellites of the [[Global Positioning System]] (GPS) in 1978. GPS used a larger constellation of satellites and improved signal transmission, thus improving accuracy. Early GPS observations required several hours of observations by a static receiver to reach survey accuracy requirements. Later improvements to both satellites and receivers allowed for [[Real Time Kinematic]] (RTK) surveying. RTK surveys provide high-accuracy measurements by using a fixed base station and a second roving antenna. The position of the roving antenna can be tracked.