LSIT Measurement Technology 3 — Questions and Answers
Question 1: A total station's EDM measures a slope distance of 452.38 ft at a vertical angle of +6°24'. What is the horizontal distance?
- 449.64 ft (Correct answer)
- 452.38 ft
- 450.01 ft
- 448.92 ft
Correct answer: 449.64 ft
Horizontal distance = slope distance × cos(vertical angle) = 452.38 × cos(6°24') ≈ 449.64 ft.
Question 2: Which type of level is most affected by atmospheric refraction and Earth's curvature over long sights?
- Trigonometric leveling (Correct answer)
- Differential leveling
- Profile leveling
- Reciprocal leveling
Correct answer: Trigonometric leveling
Trigonometric leveling uses vertical angles over long distances, making it most susceptible to refraction and curvature errors.
Question 3: A surveyor uses a prism constant of –30 mm. If the EDM reads 125.340 m to the prism, what is the corrected distance?
- 125.310 m (Correct answer)
- 125.370 m
- 125.340 m
- 124.340 m
Correct answer: 125.310 m
Corrected distance = measured distance + prism constant = 125.340 + (–0.030) = 125.310 m.
Question 4: What does 'index error' refer to in theodolite/total station usage?
- The deviation of the vertical circle index from 0° when the bubble is centered (Correct answer)
- The difference between face-left and face-right horizontal readings
- The error introduced by an off-center optical plummet
- The angular error caused by instrument tilt
Correct answer: The deviation of the vertical circle index from 0° when the bubble is centered
Index error is the amount by which the vertical circle reads something other than 0° (or 90°) when the instrument is leveled.
Question 5: Which GNSS error source is mitigated by using a dual-frequency receiver?
- Ionospheric delay (Correct answer)
- Multipath
- Satellite clock error
- Receiver noise
Correct answer: Ionospheric delay
Dual-frequency receivers can model and remove ionospheric delay because it is frequency-dependent.
Question 6: A surveyor measures a horizontal angle by repetition six times, obtaining a total arc of 643°12'18". What is the mean angle?
- 107°12'03" (Correct answer)
- 107°11'53"
- 106°12'03"
- 107°32'03"
Correct answer: 107°12'03"
Mean angle = 643°12'18" ÷ 6 = 107°12'03".
Question 7: Which feature of an automatic level compensates for small residual tilts of the instrument?
- Pendulum-suspended optical compensator (Correct answer)
- Plate bubble
- Striding level
- Foot screws
Correct answer: Pendulum-suspended optical compensator
The automatic level uses a gravity-controlled pendulum compensator to keep the line of sight horizontal within its operating range.
LSIT Measurement Technology 3
A total station's EDM measures a slope distance of 452.38 ft at a vertical angle of +6°24'.
What is the horizontal distance?