Total stations are used wherever the positions of points or both positions and heights need to be determined. A total station consists of a theodolite with a built-in distance meter and can simultaneously measure angles and distances. Here are four basic tasks you will likely be called upon to perform with your total station.
1. Extrapolating a Straight Line
2) Target point A, transit the telescope (i.e., reverse it) and mark point C1.
3) Turn the instrument 200 gon (180°) and target point A again.
4) Transit the telescope again and mark point C2. Point C, the mid-point between C1 and C2, corresponds exactly to the extrapolation of the line AB.
A line-of-sight error is responsible for the discrepancy between C1 and C2. Where the line of sight is inclined, the influence of the errors is a combination of target error, tilting-axis error, and vertical-axis error.
2. Polar Stakeout of a Point
2) Set the horizontal circle to zero (refer to the user manual).
3) Rotate the instrument until α appears in the display.
4) Guide the reflector carrier (person) into and along the line of sight of the telescope, continually measuring the horizontal distance until point P is reached.
The setting-out elements (angle and distance) here relate to a known point A and to a known starting direction from A to B.
3. Measuring Slopes
2) Enter the instrument height i and the target height t (prism). The vertical angle reading in gon or degrees can be set to % (refer to the user manual for your total station model) so that the slope can be read off directly in %.
3) Target the center of the prism and measure the distance. The slope is shown on the display in %.
4. Plumbing Up or Down
Plumbing down from a height point, plumbing up from a ground point, and inspecting a vertical line on a structure can be carried out accurately in just one telescope face, but only if the telescope describes a precisely vertical plane when it is moved up and down. To make sure this occurs, proceed as follows:
2) Transit the telescope and repeat step 1 in the second face. Mark point C.
3) The mid-point between B and C is the exact plumbing point.
If these two points do not coincide, you may have encountered a tilting-axis error and/or an inclined vertical axis. To minimize the influence of vertical-axis tilt on steep sites, be sure to level your total station precisely before beginning your work.
Article taken from the Blackboard Allen Precision Instrumnets sight