PS Surveying Methods & Techniques 5

Question 1

Which EDM (Electronic Distance Measurement) technique uses the phase difference between emitted and returned electromagnetic waves to determine distance?

Accepted Answer

Phase comparison ranging

Answer

Phase comparison EDMs measure the phase shift of a continuous modulated wave after it travels to the reflector and back, computing distance from the fractional wavelength difference.

Question 2

In a two-peg test for a dumpy level, the instrument is found to have a collimation error. The correct adjustment is made so that the line of collimation is:

Accepted Answer

Horizontal when the bubble is centered

Answer

The line of collimation must be truly horizontal when the instrument is leveled (bubble centered), which is what the two-peg test verifies and corrects.

Question 3

When computing the area of a parcel using the coordinate method (Gauss formula), the area equals:

Accepted Answer

One-half the absolute value of the sum of cross-products of consecutive coordinates

Answer

The coordinate (shoelace/Gauss) formula computes area as ½|Σ(Xᵢ(Yᵢ₊₁ − Yᵢ₋₁))|, i.e., half the absolute value of the sum of cross-products of coordinate pairs.

Question 4

A surveyor establishes a baseline of 500.00 ft and measures angles from each end to an inaccessible point. Angle at station A is 64°30' and angle at station B is 71°15'. Which method is being employed?

Accepted Answer

Triangulation (intersection)

Answer

Measuring angles to an unknown point from both ends of a known baseline to compute the point's location is the classical triangulation (intersection) method.

Question 5

LiDAR point cloud data collected from an airborne platform is referenced to ground elevation using:

Accepted Answer

Ground control points and GPS/IMU data from the aircraft

Answer

Airborne LiDAR uses onboard GPS to track the aircraft position and an IMU (Inertial Measurement Unit) to track orientation; ground control points verify and refine the absolute accuracy.

(PS) Professional Licensed Surveyor Practice Test

(PS) Professional Licensed Surveyor Practice Test

PS Surveying Methods & Techniques 5