LSIT Measurement Technology 4

Question 1

In GPS surveying, 'PDOP' stands for Position Dilution of Precision. A PDOP of 2 versus a PDOP of 6 means:

Accepted Answer

PDOP 2 yields better precision because satellites are more favorably distributed

Answer

Lower PDOP values indicate better satellite geometry, resulting in more precise position estimates.

Question 2

A leveling rod reading of 4.832 ft is taken at a point 500 ft from the instrument. What combined curvature and refraction correction should be applied?

Accepted Answer

Approximately 0.010 ft (negligible for most surveys)

Answer

Combined curvature and refraction ≈ 0.0206 × d² (miles); at 500 ft (~0.095 mi), correction ≈ 0.0002 ft, which is negligible.

Question 3

What is the purpose of 'balancing in' a level circuit?

Accepted Answer

To make backsight and foresight distances equal, minimizing collimation and curvature errors

Answer

Equal backsight and foresight distances cancel systematic errors from instrument collimation and Earth curvature.

Question 4

A laser level emits a beam that is 0.003° out of horizontal. At 200 ft, what vertical error does this introduce?

Accepted Answer

Approximately 0.010 ft

Answer

Error = 200 × tan(0.003°) ≈ 200 × 0.0000524 ≈ 0.0105 ft ≈ 0.010 ft.

Question 5

Which systematic error in EDM instruments is best detected by measuring over a calibrated baseline of multiple lengths?

Accepted Answer

Scale error (cyclic error)

Answer

Cyclic (scale) errors repeat over fixed distance intervals and are revealed by comparing EDM measurements to a known baseline at multiple distances.

(LSIT) Land Surveyor in Training Practice Test

(LSIT) Land Surveyor in Training Practice Test

LSIT Measurement Technology 4